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Old versions of Test::More
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* Old versions of Test::More
@ 2017-04-21 13:08 Andrew Dunstan <[email protected]>
  2017-04-21 14:36 ` Re: Old versions of Test::More Daniel Gustafsson <[email protected]>
  2017-04-21 14:45 ` Re: Old versions of Test::More Tom Lane <[email protected]>
  0 siblings, 2 replies; 128+ messages in thread

From: Andrew Dunstan @ 2017-04-21 13:08 UTC (permalink / raw)
  To: pgsql-hackers


As we discovered yesterday via jacana, very old versions of Test::More
don't support the note() function. It therefore seems prudent to specify
a minimum version number for the module in those scripts that use the
function. According to the changelog, version 0.82 (released in Oct
2008) should be sufficient. So I suggest the attached patch.


cheers

andrew

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PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services



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Attachments:

  [text/x-diff] test-more-version.patch (1.2K, ../../[email protected]/2-test-more-version.patch)
  download | inline diff:
diff --git a/src/test/recovery/t/001_stream_rep.pl b/src/test/recovery/t/001_stream_rep.pl
index ccd5943..29e648e 100644
--- a/src/test/recovery/t/001_stream_rep.pl
+++ b/src/test/recovery/t/001_stream_rep.pl
@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 28;
+use Test::More 0.82 tests => 28;
 
 # Initialize master node
 my $node_master = get_new_node('master');
diff --git a/src/test/recovery/t/010_logical_decoding_timelines.pl b/src/test/recovery/t/010_logical_decoding_timelines.pl
index cdddb4d..bd353ca 100644
--- a/src/test/recovery/t/010_logical_decoding_timelines.pl
+++ b/src/test/recovery/t/010_logical_decoding_timelines.pl
@@ -23,7 +23,7 @@ use warnings;
 
 use PostgresNode;
 use TestLib;
-use Test::More tests => 13;
+use Test::More 0.82 tests => 13;
 use RecursiveCopy;
 use File::Copy;
 use IPC::Run ();
diff --git a/src/test/ssl/t/001_ssltests.pl b/src/test/ssl/t/001_ssltests.pl
index 0c69bf0..4bd905d 100644
--- a/src/test/ssl/t/001_ssltests.pl
+++ b/src/test/ssl/t/001_ssltests.pl
@@ -2,7 +2,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 40;
+use Test::More 0.82 tests => 40;
 use ServerSetup;
 use File::Copy;
 


^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
@ 2017-04-21 14:36 ` Daniel Gustafsson <[email protected]>
  2017-04-21 14:42   ` Re: Old versions of Test::More Andrew Dunstan <[email protected]>
  1 sibling, 1 reply; 128+ messages in thread

From: Daniel Gustafsson @ 2017-04-21 14:36 UTC (permalink / raw)
  To: Andrew Dunstan <[email protected]>; +Cc: pgsql-hackers

> On 21 Apr 2017, at 15:08, Andrew Dunstan <[email protected]> wrote:
> 
> As we discovered yesterday via jacana, very old versions of Test::More
> don't support the note() function. It therefore seems prudent to specify
> a minimum version number for the module in those scripts that use the
> function. According to the changelog, version 0.82 (released in Oct
> 2008) should be sufficient. So I suggest the attached patch.

+1 for specifying version (0.82 was replaced with 0.84 within hours but it
doesn’t really matter for this).  However, since src/test/ssl/ServerSetup.pm
also invoke note() doesn’t it make sense to add the version requirement there
as well as a guard in case a testscript using ServerSetup isn’t explicitly
specifying the Test::More version?

cheers ./daniel



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Attachments:

  [application/octet-stream] test-more-version-v2.diff (1.5K, ../../[email protected]/2-test-more-version-v2.diff)
  download | inline diff:
diff --git a/src/test/recovery/t/001_stream_rep.pl b/src/test/recovery/t/001_stream_rep.pl
index ccd5943..29e648e 100644
--- a/src/test/recovery/t/001_stream_rep.pl
+++ b/src/test/recovery/t/001_stream_rep.pl
@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 28;
+use Test::More 0.82 tests => 28;
 
 # Initialize master node
 my $node_master = get_new_node('master');
diff --git a/src/test/recovery/t/010_logical_decoding_timelines.pl b/src/test/recovery/t/010_logical_decoding_timelines.pl
index cdddb4d..bd353ca 100644
--- a/src/test/recovery/t/010_logical_decoding_timelines.pl
+++ b/src/test/recovery/t/010_logical_decoding_timelines.pl
@@ -23,7 +23,7 @@ use warnings;
 
 use PostgresNode;
 use TestLib;
-use Test::More tests => 13;
+use Test::More 0.82 tests => 13;
 use RecursiveCopy;
 use File::Copy;
 use IPC::Run ();
diff --git a/src/test/ssl/ServerSetup.pm b/src/test/ssl/ServerSetup.pm
index 72d60e8..0e66a62 100644
--- a/src/test/ssl/ServerSetup.pm
+++ b/src/test/ssl/ServerSetup.pm
@@ -22,7 +22,7 @@ use PostgresNode;
 use TestLib;
 use File::Basename;
 use File::Copy;
-use Test::More;
+use Test::More 0.82;
 
 use Exporter 'import';
 our @EXPORT = qw(
diff --git a/src/test/ssl/t/001_ssltests.pl b/src/test/ssl/t/001_ssltests.pl
index 0c69bf0..4bd905d 100644
--- a/src/test/ssl/t/001_ssltests.pl
+++ b/src/test/ssl/t/001_ssltests.pl
@@ -2,7 +2,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 40;
+use Test::More 0.82 tests => 40;
 use ServerSetup;
 use File::Copy;
 


^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 14:36 ` Re: Old versions of Test::More Daniel Gustafsson <[email protected]>
@ 2017-04-21 14:42   ` Andrew Dunstan <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Andrew Dunstan @ 2017-04-21 14:42 UTC (permalink / raw)
  To: Daniel Gustafsson <[email protected]>; +Cc: pgsql-hackers



On 04/21/2017 10:36 AM, Daniel Gustafsson wrote:
>> On 21 Apr 2017, at 15:08, Andrew Dunstan <[email protected]> wrote:
>>
>> As we discovered yesterday via jacana, very old versions of Test::More
>> don't support the note() function. It therefore seems prudent to specify
>> a minimum version number for the module in those scripts that use the
>> function. According to the changelog, version 0.82 (released in Oct
>> 2008) should be sufficient. So I suggest the attached patch.
> +1 for specifying version (0.82 was replaced with 0.84 within hours but it
> doesn’t really matter for this).  However, since src/test/ssl/ServerSetup.pm
> also invoke note() doesn’t it make sense to add the version requirement there
> as well as a guard in case a testscript using ServerSetup isn’t explicitly
> specifying the Test::More version?
>


Yeah, good catch. Will do.

cheers

andrew

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PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services



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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
@ 2017-04-21 14:45 ` Tom Lane <[email protected]>
  2017-04-21 18:49   ` Re: Old versions of Test::More Andrew Dunstan <[email protected]>
  1 sibling, 1 reply; 128+ messages in thread

From: Tom Lane @ 2017-04-21 14:45 UTC (permalink / raw)
  To: Andrew Dunstan <[email protected]>; +Cc: pgsql-hackers

Andrew Dunstan <[email protected]> writes:
> As we discovered yesterday via jacana, very old versions of Test::More
> don't support the note() function. It therefore seems prudent to specify
> a minimum version number for the module in those scripts that use the
> function. According to the changelog, version 0.82 (released in Oct
> 2008) should be sufficient. So I suggest the attached patch.

Maybe it'd be better to put the minimum-version check somewhere central,
like PostgresNode.pm?  I suppose that our use of "note" will expand,
and I can't see us remembering to put this into all and only the specific
tests that use "note".  Especially if there's no comment about it.

			regards, tom lane


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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 14:45 ` Re: Old versions of Test::More Tom Lane <[email protected]>
@ 2017-04-21 18:49   ` Andrew Dunstan <[email protected]>
  2017-04-21 19:55     ` Re: Old versions of Test::More Peter Eisentraut <[email protected]>
  0 siblings, 1 reply; 128+ messages in thread

From: Andrew Dunstan @ 2017-04-21 18:49 UTC (permalink / raw)
  To: Tom Lane <[email protected]>; +Cc: pgsql-hackers



On 04/21/2017 10:45 AM, Tom Lane wrote:
> Andrew Dunstan <[email protected]> writes:
>> As we discovered yesterday via jacana, very old versions of Test::More
>> don't support the note() function. It therefore seems prudent to specify
>> a minimum version number for the module in those scripts that use the
>> function. According to the changelog, version 0.82 (released in Oct
>> 2008) should be sufficient. So I suggest the attached patch.
> Maybe it'd be better to put the minimum-version check somewhere central,
> like PostgresNode.pm?  I suppose that our use of "note" will expand,
> and I can't see us remembering to put this into all and only the specific
> tests that use "note".  Especially if there's no comment about it.
>
> 			


I'll add a comment, but doing it in PostgresNode.pm would mean jacana
(for instance) couldn't run any of the TAP tests. I'mm looking at
installing a sufficiently modern Test::Simple package (includes
Test::More and test::Build) there, but other oldish machines could also
be affected.


cheers

andrew

-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services



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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 14:45 ` Re: Old versions of Test::More Tom Lane <[email protected]>
  2017-04-21 18:49   ` Re: Old versions of Test::More Andrew Dunstan <[email protected]>
@ 2017-04-21 19:55     ` Peter Eisentraut <[email protected]>
  2017-04-21 20:21       ` Re: Old versions of Test::More Tom Lane <[email protected]>
  0 siblings, 1 reply; 128+ messages in thread

From: Peter Eisentraut @ 2017-04-21 19:55 UTC (permalink / raw)
  To: Andrew Dunstan <[email protected]>; Tom Lane <[email protected]>; +Cc: pgsql-hackers

On 4/21/17 14:49, Andrew Dunstan wrote:
> I'll add a comment, but doing it in PostgresNode.pm would mean jacana
> (for instance) couldn't run any of the TAP tests. I'mm looking at
> installing a sufficiently modern Test::Simple package (includes
> Test::More and test::Build) there, but other oldish machines could also
> be affected.

Or you could define note() as an empty function if it doesn't exist.

-- 
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PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 14:45 ` Re: Old versions of Test::More Tom Lane <[email protected]>
  2017-04-21 18:49   ` Re: Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 19:55     ` Re: Old versions of Test::More Peter Eisentraut <[email protected]>
@ 2017-04-21 20:21       ` Tom Lane <[email protected]>
  2017-04-22 01:22         ` Re: Old versions of Test::More Craig Ringer <[email protected]>
  0 siblings, 1 reply; 128+ messages in thread

From: Tom Lane @ 2017-04-21 20:21 UTC (permalink / raw)
  To: Peter Eisentraut <[email protected]>; +Cc: Andrew Dunstan <[email protected]>; pgsql-hackers

Peter Eisentraut <[email protected]> writes:
> On 4/21/17 14:49, Andrew Dunstan wrote:
>> I'll add a comment, but doing it in PostgresNode.pm would mean jacana
>> (for instance) couldn't run any of the TAP tests. I'mm looking at
>> installing a sufficiently modern Test::Simple package (includes
>> Test::More and test::Build) there, but other oldish machines could also
>> be affected.

> Or you could define note() as an empty function if it doesn't exist.

+1.  I'm really not at all happy with the prospect that every time
somebody adds a use of "note" to some new TAP test, we're going to
get a complaint later that that test no longer works on jacana.
We need to either decide that non-ancient Test::More is a hard
requirement for all the tests, or fix things with a centralized
solution.  A dummy (or not so dummy?) implementation would serve
for the latter.

			regards, tom lane


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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 14:45 ` Re: Old versions of Test::More Tom Lane <[email protected]>
  2017-04-21 18:49   ` Re: Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 19:55     ` Re: Old versions of Test::More Peter Eisentraut <[email protected]>
  2017-04-21 20:21       ` Re: Old versions of Test::More Tom Lane <[email protected]>
@ 2017-04-22 01:22         ` Craig Ringer <[email protected]>
  2017-04-22 14:29           ` Re: Old versions of Test::More Andrew Dunstan <[email protected]>
  0 siblings, 1 reply; 128+ messages in thread

From: Craig Ringer @ 2017-04-22 01:22 UTC (permalink / raw)
  To: Tom Lane <[email protected]>; +Cc: pgsql-hackers; Andrew Dunstan <[email protected]>; Peter Eisentraut <[email protected]>

On 22 Apr. 2017 4:23 am, "Tom Lane" <[email protected]> wrote:

Peter Eisentraut <[email protected]> writes:
> On 4/21/17 14:49, Andrew Dunstan wrote:
>> I'll add a comment, but doing it in PostgresNode.pm would mean jacana
>> (for instance) couldn't run any of the TAP tests. I'mm looking at
>> installing a sufficiently modern Test::Simple package (includes
>> Test::More and test::Build) there, but other oldish machines could also
>> be affected.

> Or you could define note() as an empty function if it doesn't exist.

+1.  I'm really not at all happy with the prospect that every time
somebody adds a use of "note" to some new TAP test, we're going to
get a complaint later that that test no longer works on jacana.
We need to either decide that non-ancient Test::More is a hard
requirement for all the tests


That seems like a no-brainer TBH. Why are we bothering with backwards
compat with ancient versions of test frameworks? It seems like a colossal
waste of time for no benefit.

or fix things with a centralized
solution.  A dummy (or not so dummy?) implementation would serve
for the latter.

                        regards, tom lane


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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* Re: Old versions of Test::More
  2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 14:45 ` Re: Old versions of Test::More Tom Lane <[email protected]>
  2017-04-21 18:49   ` Re: Old versions of Test::More Andrew Dunstan <[email protected]>
  2017-04-21 19:55     ` Re: Old versions of Test::More Peter Eisentraut <[email protected]>
  2017-04-21 20:21       ` Re: Old versions of Test::More Tom Lane <[email protected]>
  2017-04-22 01:22         ` Re: Old versions of Test::More Craig Ringer <[email protected]>
@ 2017-04-22 14:29           ` Andrew Dunstan <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Andrew Dunstan @ 2017-04-22 14:29 UTC (permalink / raw)
  To: Craig Ringer <[email protected]>; Tom Lane <[email protected]>; +Cc: pgsql-hackers; Peter Eisentraut <[email protected]>



On 04/21/2017 09:22 PM, Craig Ringer wrote:
>
>
> On 22 Apr. 2017 4:23 am, "Tom Lane" <[email protected]
> <mailto:[email protected]>> wrote:
>
>     Peter Eisentraut <[email protected]
>     <mailto:[email protected]>> writes:
>     > On 4/21/17 14:49, Andrew Dunstan wrote:
>     >> I'll add a comment, but doing it in PostgresNode.pm would mean
>     jacana
>     >> (for instance) couldn't run any of the TAP tests. I'mm looking at
>     >> installing a sufficiently modern Test::Simple package (includes
>     >> Test::More and test::Build) there, but other oldish machines
>     could also
>     >> be affected.
>
>     > Or you could define note() as an empty function if it doesn't exist.
>
>     +1.  I'm really not at all happy with the prospect that every time
>     somebody adds a use of "note" to some new TAP test, we're going to
>     get a complaint later that that test no longer works on jacana.
>     We need to either decide that non-ancient Test::More is a hard
>     requirement for all the tests
>
>
> That seems like a no-brainer TBH. Why are we bothering with backwards
> compat with ancient versions of test frameworks? It seems like a
> colossal waste of time for no benefit.
>


OK, I have pushed a requirement for a minimum version of Test::More into
TestLib.pm, a better place for it than PostgresNode.pm as not all tests
use the latter.

jacana has been upgraded to use a sufficiently modern Test::More.


cheers

andrew

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PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services



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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
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Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
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---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
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Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 07/12] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 7adeaedd0e..5e24af9cb3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index b64db82f02..2aedddc1d8 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2107,7 +2107,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--9Ek0hoCL9XbhcSqy
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


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 filename="v24-0007-Add-support-for-PRESERVE.patch"
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* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
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Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v21 3/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  14 ++
 src/backend/commands/tablecmds.c            | 208 ++++++++++++++++----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  59 ++++++
 src/test/regress/expected/compression_1.out |  57 ++++++
 src/test/regress/sql/compression.sql        |  21 ++
 9 files changed, 329 insertions(+), 45 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..c4b53ec1c5 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +384,19 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This clause adds compression to a column. The Compression method can be
+      set to any available compression method.  The built-in methods are
+      <literal>pglz</literal> and <literal>lz4</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 082db26bfa..89cca760c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5527,6 +5535,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					CompareCompressionMethodAndDecompress(oldslot, newTupDesc);
+
 				/* copy attributes */
 				memcpy(newslot->tts_values, oldslot->tts_values,
 					   sizeof(Datum) * oldslot->tts_nvalid);
@@ -7767,6 +7778,71 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression or attstorage for the respective index attribute.  If
+ * attcompression is a valid oid then it will update the attcompression for the
+ * index attribute otherwise it will update the attstorage.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			/*
+			 * If a valid compression method Oid is passed then update the
+			 * attcompression, otherwise update the attstorage.
+			 */
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+			else
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7858,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7921,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15069,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 355e273192..f2e9fe4ff8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2307,6 +2307,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 17f7265038..7aeabf9543 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 232c9f1248..ffb739f565 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1875,7 +1875,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 4dea269fc3..84d31c781b 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -142,6 +142,65 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the partioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index a50c7679bb..3250c12859 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -139,6 +139,63 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+(0 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+(0 rows)
+
+-- test alter compression method for the partioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0750a6c80e..3b0da88c19 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -65,6 +65,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--ytoMbUMiTKPMT3hY
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v21-0004-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
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Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
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Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
Content-Transfer-Encoding: 8bit



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
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Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 6/7] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--YZ5djTAD1cGYuMQK
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v24 06/10] alter table set compression
@ 2020-12-18 06:01 dilipkumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: dilipkumar @ 2020-12-18 06:01 UTC (permalink / raw)

Add support for changing the compression method associated
with a column, forcing a table rewrite.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/createas.c             |   3 +-
 src/backend/commands/matview.c              |   3 +-
 src/backend/commands/tablecmds.c            | 226 +++++++++++++++-----
 src/backend/executor/nodeModifyTable.c      |   9 +-
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/commands/event_trigger.h        |   1 +
 src/include/executor/executor.h             |   3 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  93 ++++++--
 src/test/regress/expected/compression_1.out |  56 ++++-
 src/test/regress/sql/compression.sql        |  21 ++
 13 files changed, 370 insertions(+), 75 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 1d17dc0d6b..748ec29570 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -589,7 +589,8 @@ intorel_receive(TupleTableSlot *slot, DestReceiver *self)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 													 &myState->decompress_tuple_slot,
-													 myState->rel->rd_att);
+													 myState->rel->rd_att,
+													 NULL);
 
 		/*
 		 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 713fc3fceb..779b4e51cf 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -494,7 +494,8 @@ transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
 	 */
 	slot = CompareCompressionMethodAndDecompress(slot,
 												 &myState->decompress_tuple_slot,
-												 myState->transientrel->rd_att);
+												 myState->transientrel->rd_att,
+												 NULL);
 
 	/*
 	 * Note that the input slot might not be of the type of the target
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 72ba017814..586a92f0c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -529,6 +529,8 @@ static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3968,6 +3970,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4495,7 +4498,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4903,6 +4907,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5519,6 +5527,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 		while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
 		{
+			bool		decompressed = false;
 			TupleTableSlot *insertslot;
 
 			if (tab->rewrite > 0)
@@ -5527,11 +5536,25 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				slot_getallattrs(oldslot);
 				ExecClearTuple(newslot);
 
-				/* copy attributes */
-				memcpy(newslot->tts_values, oldslot->tts_values,
-					   sizeof(Datum) * oldslot->tts_nvalid);
-				memcpy(newslot->tts_isnull, oldslot->tts_isnull,
-					   sizeof(bool) * oldslot->tts_nvalid);
+				if (tab->rewrite & AT_REWRITE_ALTER_COMPRESSION)
+					(void) CompareCompressionMethodAndDecompress(oldslot,
+																 &newslot,
+																 newTupDesc,
+																 &decompressed);
+
+				/*
+				 * copy attributes, if we have decompressed some attribute then
+				 * the values and nulls array is already copied
+				 */
+				if (!decompressed)
+				{
+					memcpy(newslot->tts_values, oldslot->tts_values,
+						   sizeof(Datum) * oldslot->tts_nvalid);
+					memcpy(newslot->tts_isnull, oldslot->tts_isnull,
+						   sizeof(bool) * oldslot->tts_nvalid);
+				}
+				else
+					ExecClearTuple(newslot);
 
 				/* Set dropped attributes to null in new tuple */
 				foreach(lc, dropped_attrs)
@@ -7767,6 +7790,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and attstorage for the respective index attribute if
+ * the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  Oid newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (OidIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7782,7 +7866,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7846,47 +7929,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidOid, newstorage,
+						  lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15033,6 +15077,92 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* Prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* Initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* Get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	if (atttableform->attcompression != cmoid)
+		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 920d9dd0d5..ea82a05591 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2052,7 +2052,8 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 TupleTableSlot *
 CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 									  TupleTableSlot **outslot,
-									  TupleDesc targetTupDesc)
+									  TupleDesc targetTupDesc,
+									  bool *decompressed)
 {
 	int			i;
 	int			attnum;
@@ -2139,6 +2140,9 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 		*outslot = newslot;
 
+		if (decompressed != NULL)
+			*decompressed = true;
+
 		return newslot;
 	}
 
@@ -2360,7 +2364,8 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		slot = CompareCompressionMethodAndDecompress(slot,
 									&node->mt_decompress_tuple_slot,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									resultRelInfo->ri_RelationDesc->rd_att,
+									NULL);
 
 		switch (operation)
 		{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 52d92df25d..30acfe615d 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 1e1c315bae..ffa8d05edf 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2098,7 +2098,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h
index c11bf2d781..5a314f4c1d 100644
--- a/src/include/commands/event_trigger.h
+++ b/src/include/commands/event_trigger.h
@@ -32,6 +32,7 @@ typedef struct EventTriggerData
 #define AT_REWRITE_ALTER_PERSISTENCE	0x01
 #define AT_REWRITE_DEFAULT_VAL			0x02
 #define AT_REWRITE_COLUMN_REWRITE		0x04
+#define AT_REWRITE_ALTER_COMPRESSION	0x08
 
 /*
  * EventTriggerData is the node type that is passed as fmgr "context" info
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 6495162a33..050ef2dcd0 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -623,5 +623,6 @@ extern void CheckSubscriptionRelkind(char relkind, const char *nspname,
 									 const char *relname);
 extern TupleTableSlot *CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 												  TupleTableSlot **outslot,
-												  TupleDesc targetTupDesc);
+												  TupleDesc targetTupDesc,
+												  bool *decompressed);
 #endif							/* EXECUTOR_H  */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 167878e78b..21c1b451d2 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -4,20 +4,20 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
 CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4);
 INSERT INTO cmdata1 VALUES(repeat('1234567890',1004));
 \d+ cmdata1
-                                 Table "public.cmdata1"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata1"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- try setting compression for incompressible data type
 CREATE TABLE cmdata2 (f1 int COMPRESSION pglz);
@@ -112,18 +112,18 @@ DROP TABLE cmdata2;
 -- test LIKE INCLUDING COMPRESSION
 CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION);
 \d+ cmdata2
-                                 Table "public.cmdata2"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata2"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
 
 -- test compression with materialized view
 CREATE MATERIALIZED VIEW mv(x) AS SELECT * FROM cmdata1;
 \d+ mv
-                             Materialized view "public.mv"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- x      | text |           |          |         | extended |              | 
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | pglz        |              | 
 View definition:
  SELECT cmdata1.f1 AS x
    FROM cmdata1;
@@ -165,6 +165,67 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+SELECT pg_column_compression(f1) FROM cmdata1;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+SELECT pg_column_compression(x) FROM mv;
+ pg_column_compression 
+-----------------------
+ lz4
+ lz4
+(2 rows)
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 329e7881b0..64c5855bf7 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -4,10 +4,10 @@ CREATE TABLE cmdata(f1 text COMPRESSION pglz);
 CREATE INDEX idx ON cmdata(f1);
 INSERT INTO cmdata VALUES(repeat('1234567890',1000));
 \d+ cmdata
-                                 Table "public.cmdata"
- Column | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
- f1     | text |           |          |         | extended |              | 
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
 Indexes:
     "idx" btree (f1)
 
@@ -157,6 +157,54 @@ CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+(1 row)
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmdata1" does not exist
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+REFRESH MATERIALIZED VIEW mv;
+ERROR:  relation "mv" does not exist
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+ERROR:  relation "cmdata1" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmdata1;
+                                              ^
+SELECT pg_column_compression(x) FROM mv;
+ERROR:  relation "mv" does not exist
+LINE 1: SELECT pg_column_compression(x) FROM mv;
+                                             ^
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart" does not exist
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 450416ecb4..b9daa33b74 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -75,6 +75,27 @@ SELECT pg_column_compression(f1) FROM cmpart;
 CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
 
+-- test alter compression method with rewrite
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER TABLE cmdata1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+REFRESH MATERIALIZED VIEW mv;
+\d+ mv
+SELECT pg_column_compression(f1) FROM cmdata1;
+SELECT pg_column_compression(x) FROM mv;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart ALTER COLUMN f1 SET COMPRESSION pglz;
+SELECT pg_column_compression(f1) FROM cmpart;
+
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--m51xatjYGsM+13rf
Content-Type: text/x-diff; charset=iso-8859-1
Content-Disposition: attachment;
 filename="v24-0007-Add-support-for-PRESERVE.patch"
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^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 4/5] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c25ef5abd6..0bd0c1a503 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -103,6 +104,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -383,6 +385,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 745dfe9570..f9bda942a3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -528,6 +528,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3973,6 +3975,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4500,7 +4503,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4908,6 +4912,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7772,6 +7780,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7787,7 +7856,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7851,47 +7919,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15016,6 +15045,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d923b5d95..5c4e779ca0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ecdb8d752b..2071a29bf0 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 19d2ba26bf..f9a87dee02 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1901,7 +1901,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 12ab404900..3bfe2358f4 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -227,12 +227,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index cc9b913418..59175b935b 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -227,12 +227,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 0d5a2231d0..1f417b7d94 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -100,6 +100,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--nHwqXXcoX0o6fKCv
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0005-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--C94crkcyjafcjHxo
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 7/8] Alter table set compression
@ 2021-03-10 09:04 Dilip Kumar <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Dilip Kumar @ 2021-03-10 09:04 UTC (permalink / raw)

Add support for changing the compression method associated
with a column.  There are only built-in methods so we don't
need to rewrite the table, only the new tuples will be
compressed with the new compression method.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Robert Haas and Tomas Vondra.
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby

Discussions:
https://www.postgresql.org/message-id/[email protected]
https://www.postgresql.org/message-id/CA%2BTgmoaKDW1Oi9V%3Djc9hOGyf77NbkNEABuqgHD1Cq%3D%3D1QsOcxg%40...
https://www.postgresql.org/message-id/CA%2BTgmobSDVgUage9qQ5P_%3DF_9jaMkCgyKxUQGtFQU7oN4kX-AA%40mail...
https://www.postgresql.org/message-id/20201005160355.byp74sh3ejsv7wrj%40development
https://www.postgresql.org/message-id/CAFiTN-tzTTT2oqWdRGLv1dvvS5MC1W%2BLE%2B3bqWPJUZj4GnHOJg%40mail...
---
 doc/src/sgml/ref/alter_table.sgml           |  16 ++
 src/backend/commands/tablecmds.c            | 198 +++++++++++++++-----
 src/backend/parser/gram.y                   |   9 +
 src/bin/psql/tab-complete.c                 |   2 +-
 src/include/nodes/parsenodes.h              |   3 +-
 src/test/regress/expected/compression.out   |  47 ++++-
 src/test/regress/expected/compression_1.out |  48 ++++-
 src/test/regress/sql/compression.sql        |  20 ++
 8 files changed, 296 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 38e416d183..e147831640 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,6 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -104,6 +105,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -384,6 +386,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+    </term>
+    <listitem>
+     <para>
+      This sets the compression method for a column.  The supported compression
+      methods are <literal>pglz</literal> and <literal>lz4</literal>.
+      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
+      was used when building <productname>PostgreSQL</productname>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
     <listitem>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a0d2af0cde..bb284741ce 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -532,6 +532,8 @@ static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKM
 static void ATExecGenericOptions(Relation rel, List *options);
 static void ATExecSetRowSecurity(Relation rel, bool rls);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
+static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
+					 const char *column, Node *newValue, LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -3977,6 +3979,7 @@ AlterTableGetLockLevel(List *cmds)
 				 */
 			case AT_GenericOptions:
 			case AT_AlterColumnGenericOptions:
+			case AT_SetCompression:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4511,7 +4514,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DisableRowSecurity:
 		case AT_ForceRowSecurity:
 		case AT_NoForceRowSecurity:
-			ATSimplePermissions(rel, ATT_TABLE);
+		case AT_SetCompression:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW);
 			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
@@ -4924,6 +4928,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
+		case AT_SetCompression:
+			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+										   lockmode);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -7812,6 +7820,67 @@ ATExecSetOptions(Relation rel, const char *colName, Node *options,
 	return address;
 }
 
+/*
+ * Helper function for ATExecSetStorage and ATExecSetCompression
+ *
+ * Set the attcompression and/or attstorage for the respective index attribute
+ * if the respective input values are valid.
+ */
+static void
+ApplyChangesToIndexes(Relation rel, Relation attrelation, AttrNumber attnum,
+					  char newcompression, char newstorage, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	ListCell   *lc;
+	Form_pg_attribute attrtuple;
+
+	foreach(lc, RelationGetIndexList(rel))
+	{
+		Oid			indexoid = lfirst_oid(lc);
+		Relation	indrel;
+		AttrNumber	indattnum = 0;
+
+		indrel = index_open(indexoid, lockmode);
+
+		for (int i = 0; i < indrel->rd_index->indnatts; i++)
+		{
+			if (indrel->rd_index->indkey.values[i] == attnum)
+			{
+				indattnum = i + 1;
+				break;
+			}
+		}
+
+		if (indattnum == 0)
+		{
+			index_close(indrel, lockmode);
+			continue;
+		}
+
+		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
+
+		if (HeapTupleIsValid(tuple))
+		{
+			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
+
+			if (CompressionMethodIsValid(newcompression))
+				attrtuple->attcompression = newcompression;
+
+			if (newstorage != '\0')
+				attrtuple->attstorage = newstorage;
+
+			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+			InvokeObjectPostAlterHook(RelationRelationId,
+									  RelationGetRelid(rel),
+									  attrtuple->attnum);
+
+			heap_freetuple(tuple);
+		}
+
+		index_close(indrel, lockmode);
+	}
+}
 /*
  * ALTER TABLE ALTER COLUMN SET STORAGE
  *
@@ -7827,7 +7896,6 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
-	ListCell   *lc;
 
 	Assert(IsA(newValue, String));
 	storagemode = strVal(newValue);
@@ -7891,47 +7959,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE loc
 	 * Apply the change to indexes as well (only for simple index columns,
 	 * matching behavior of index.c ConstructTupleDescriptor()).
 	 */
-	foreach(lc, RelationGetIndexList(rel))
-	{
-		Oid			indexoid = lfirst_oid(lc);
-		Relation	indrel;
-		AttrNumber	indattnum = 0;
-
-		indrel = index_open(indexoid, lockmode);
-
-		for (int i = 0; i < indrel->rd_index->indnatts; i++)
-		{
-			if (indrel->rd_index->indkey.values[i] == attnum)
-			{
-				indattnum = i + 1;
-				break;
-			}
-		}
-
-		if (indattnum == 0)
-		{
-			index_close(indrel, lockmode);
-			continue;
-		}
-
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
-
-		if (HeapTupleIsValid(tuple))
-		{
-			attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
-			attrtuple->attstorage = newstorage;
-
-			CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-			InvokeObjectPostAlterHook(RelationRelationId,
-									  RelationGetRelid(rel),
-									  attrtuple->attnum);
-
-			heap_freetuple(tuple);
-		}
-
-		index_close(indrel, lockmode);
-	}
+	ApplyChangesToIndexes(rel, attrelation, attnum, InvalidCompressionMethod,
+						  newstorage, lockmode);
 
 	table_close(attrelation, RowExclusiveLock);
 
@@ -15118,6 +15147,89 @@ ATExecGenericOptions(Relation rel, List *options)
 	heap_freetuple(tuple);
 }
 
+/*
+ * ALTER TABLE ALTER COLUMN SET COMPRESSION
+ *
+ * Return value is the address of the modified column
+ */
+static ObjectAddress
+ATExecSetCompression(AlteredTableInfo *tab,
+					 Relation rel,
+					 const char *column,
+					 Node *newValue,
+					 LOCKMODE lockmode)
+{
+	Relation	attrel;
+	HeapTuple	tuple;
+	Form_pg_attribute atttableform;
+	AttrNumber	attnum;
+	char	   *compression;
+	char		typstorage;
+	Oid			cmoid;
+	Datum		values[Natts_pg_attribute];
+	bool		nulls[Natts_pg_attribute];
+	bool		replace[Natts_pg_attribute];
+	ObjectAddress address;
+
+	Assert(IsA(newValue, String));
+	compression = strVal(newValue);
+
+	attrel = table_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						column, RelationGetRelationName(rel))));
+
+	/* prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = atttableform->attnum;
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", column)));
+
+	typstorage = get_typstorage(atttableform->atttypid);
+
+	/* prevent from setting compression methods for uncompressible type */
+	if (!IsStorageCompressible(typstorage))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("column data type %s does not support compression",
+						format_type_be(atttableform->atttypid))));
+
+	/* initialize buffers for new tuple values */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replace, false, sizeof(replace));
+
+	/* get the attribute compression method. */
+	cmoid = GetAttributeCompression(atttableform, compression);
+
+	atttableform->attcompression = cmoid;
+	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  atttableform->attnum);
+
+	ReleaseSysCache(tuple);
+
+	/* apply changes to the index column as well */
+	ApplyChangesToIndexes(rel, attrel, attnum, cmoid, '\0', lockmode);
+	table_close(attrel, RowExclusiveLock);
+
+	/* make changes visible */
+	CommandCounterIncrement();
+
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), atttableform->attnum);
+	return address;
+}
+
+
 /*
  * Preparation phase for SET LOGGED/UNLOGGED
  *
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index f8bc11d28b..07aa3c9330 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2308,6 +2308,15 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
+			| ALTER opt_column ColId SET optColumnCompression
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetCompression;
+					n->name = $3;
+					n->def = (Node *) makeString($5);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fdd1bdd92a..ebe07a17cd 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2115,7 +2115,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
-		COMPLETE_WITH("(", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
+		COMPLETE_WITH("(", "COMPRESSION", "DEFAULT", "NOT NULL", "STATISTICS", "STORAGE");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET ( */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 56e24529f1..b20c03f691 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1902,7 +1902,8 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion /* ALTER COLLATION ... REFRESH VERSION */
+	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
+	AT_SetCompression			/* SET COMPRESSION */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 9ddffc8b18..19625708a9 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -247,12 +247,57 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | lz4         |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | lz4         |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ lz4
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+                                    Materialized view "public.mv"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ x      | text |           |          |         | extended | lz4         |              | 
+View definition:
+ SELECT cmdata1.f1 AS x
+   FROM cmdata1;
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+SELECT pg_column_compression(f1) FROM cmpart;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+ pglz
+ lz4
+(4 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 03a7f46554..bd642634a6 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -256,12 +256,58 @@ CREATE TABLE cmdata2 (f1 text);
 --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
  f1     | text |           |          |         | extended | pglz        |              | 
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+ERROR:  relation "mv" does not exist
+\d+ mv
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ERROR:  relation "cmpart1" does not exist
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+ERROR:  unsupported LZ4 compression method
+DETAIL:  This functionality requires the server to be built with lz4 support.
+HINT:  You need to rebuild PostgreSQL using --with-lz4.
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',1004));
+                    ^
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+ERROR:  relation "cmpart" does not exist
+LINE 1: INSERT INTO cmpart VALUES (repeat('123456789',4004));
+                    ^
+SELECT pg_column_compression(f1) FROM cmpart;
+ERROR:  relation "cmpart" does not exist
+LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
+                                              ^
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  36036
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 6c9b24f1f7..00b1ff1137 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -111,6 +111,26 @@ DROP TABLE cmdata2;
 CREATE TABLE cmdata2 (f1 text);
 \d+ cmdata2
 
+-- test alter compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4;
+INSERT INTO cmdata VALUES (repeat('123456789',4004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+
+-- test alter compression method for the materialized view
+ALTER MATERIALIZED VIEW mv ALTER COLUMN x SET COMPRESSION lz4;
+\d+ mv
+
+-- test alter compression method for the partitioned table
+ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
+ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
+
+-- new data should be compressed with the current compression method
+INSERT INTO cmpart VALUES (repeat('123456789',1004));
+INSERT INTO cmpart VALUES (repeat('123456789',4004));
+
+SELECT pg_column_compression(f1) FROM cmpart;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0


--cvVnyQ+4j833TQvp
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="0008-default-to-with-lz4.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* RE: PL/Python initialization cleanup
@ 2026-01-13 06:15 li carol <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: li carol @ 2026-01-13 06:15 UTC (permalink / raw)
  To: Matheus Alcantara <[email protected]>; Peter Eisentraut <[email protected]>; pgsql-hackers

> On 12/01/26 09:24, Peter Eisentraut wrote:
> >> 0001, 0003 and 0004 looks good to me, just a small comment on 0002:
> >>
> >> -    /*
> >> -     * PyModule_AddObject does not add a refcount to the object, for
> >> some odd
> >> -     * reason; we must do that.
> >> -     */
> >> -    Py_INCREF(exc);
> >> -    PyModule_AddObject(mod, modname, exc);
> >> -
> >>       /*
> >>        * The caller will also store a pointer to the exception object
> >> in some
> >> -     * permanent variable, so add another ref to account for that.
> >> This is
> >> -     * probably excessively paranoid, but let's be sure.
> >> +     * permanent variable, so add another ref to account for that.
> >>        */
> >>       Py_INCREF(exc);
> >>
> >> The later code comment say "so add another ref to account for that",
> >> but you've removed the previous Py_INCREF() call. The returned object
> >> PyErr_NewException() already have a refcount increased for usage? If
> >> that's not the case I think that the "add another ref..." don't seems
> >> correct because IIUC we are increasing the ref count for the first
> >> time, so there is no "another" refcount being increased.
> >
> > The reference created by PyErr_NewException() is "stolen" by
> > PyModule_AddObject(), so we need to create another one for returning
> > the object from the function and storing it in the permanent variable.
> > I have updated the comment in this new patch version.  But I think the
> > actual code is correct.
> 
> Thanks, it looks more clear IMHO now. Agree that the code is correct.
> 
> 
> --
> Matheus Alcantara
> EDB: https://www.enterprisedb.com

Hi Peter,
I have applied and reviewed the v2 patch set. The cleanup of the initialization flow is a very good improvement and makes the logic much easier to follow.
In particular, the updated comments in PLy_create_exception regarding the reference counting logic are very helpful and clarify the previous ambiguity.
I have one minor nitpick in plpy_main.c regarding consistency. In _PG_init(), the import and dictionary insertion of the "plpy" module is currently split into two checks with the same error message. To make it more consistent with how the __main__ module is handled earlier in the same function, we could potentially streamline it like this:
	/*
	 * Import plpy.
	 */
	plpy_mod = PyImport_ImportModule("plpy");
	if (plpy_mod == NULL || PyDict_SetItemString(main_dict, "plpy", plpy_mod) < 0)
		PLy_elog(ERROR, "could not import \"plpy\" module");

This is just a small suggestion for style consistency; the existing logic in v2 is perfectly correct.

Regards,
Yuan Li(carol)



^ permalink  raw  reply  [nested|flat] 128+ messages in thread


end of thread, other threads:[~2026-01-13 06:15 UTC | newest]

Thread overview: 128+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2017-04-21 13:08 Old versions of Test::More Andrew Dunstan <[email protected]>
2017-04-21 14:36 ` Daniel Gustafsson <[email protected]>
2017-04-21 14:42   ` Andrew Dunstan <[email protected]>
2017-04-21 14:45 ` Tom Lane <[email protected]>
2017-04-21 18:49   ` Andrew Dunstan <[email protected]>
2017-04-21 19:55     ` Peter Eisentraut <[email protected]>
2017-04-21 20:21       ` Tom Lane <[email protected]>
2017-04-22 01:22         ` Craig Ringer <[email protected]>
2017-04-22 14:29           ` Andrew Dunstan <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH 07/12] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v21 3/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 6/7] alter table set compression dilipkumar <[email protected]>
2020-12-18 06:01 [PATCH v24 06/10] alter table set compression dilipkumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 4/5] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2021-03-10 09:04 [PATCH 7/8] Alter table set compression Dilip Kumar <[email protected]>
2026-01-13 06:15 RE: PL/Python initialization cleanup li carol <[email protected]>

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