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* [PATCH v22 09/10] pg_ls_*dir to return all the metadata from pg_stat_file..
@ 2020-03-10 02:56 Justin Pryzby <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Justin Pryzby @ 2020-03-10 02:56 UTC (permalink / raw)
..but it doesn't seem worth factoring out the common bits, since stat_file
doesn't return a name, so all the field numbers are off by one.
NOTE, the atime is now shown where the mtime used to be.
Need catversion bump
---
doc/src/sgml/func.sgml | 37 +++++++---
src/backend/utils/adt/genfile.c | 71 +++++++++-----------
src/include/catalog/pg_proc.dat | 34 +++++-----
src/test/regress/expected/misc_functions.out | 16 ++---
src/test/regress/output/tablespace.source | 8 +--
5 files changed, 89 insertions(+), 77 deletions(-)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 7baf2b31e5..809483feed 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -25758,7 +25758,10 @@ SELECT pg_size_pretty(sum(pg_relation_size(relid))) AS total_size
<returnvalue>setof record</returnvalue>
( <parameter>name</parameter> <type>text</type>,
<parameter>size</parameter> <type>bigint</type>,
+ <parameter>access</parameter> <type>timestamp with time zone</type>,
<parameter>modification</parameter> <type>timestamp with time zone</type>,
+ <parameter>change</parameter> <type>timestamp with time zone</type>,
+ <parameter>creation</parameter> <type>timestamp with time zone</type>,
<parameter>isdir</parameter> <type>boolean</type> )
</para>
<para>
@@ -25778,7 +25781,10 @@ SELECT pg_size_pretty(sum(pg_relation_size(relid))) AS total_size
<returnvalue>setof record</returnvalue>
( <parameter>name</parameter> <type>text</type>,
<parameter>size</parameter> <type>bigint</type>,
+ <parameter>access</parameter> <type>timestamp with time zone</type>,
<parameter>modification</parameter> <type>timestamp with time zone</type>,
+ <parameter>change</parameter> <type>timestamp with time zone</type>,
+ <parameter>creation</parameter> <type>timestamp with time zone</type>,
<parameter>isdir</parameter> <type>boolean</type> )
</para>
<para>
@@ -25810,13 +25816,16 @@ LATERAL pg_ls_dir_recurse(dir) AS a;
<returnvalue>setof record</returnvalue>
( <parameter>name</parameter> <type>text</type>,
<parameter>size</parameter> <type>bigint</type>,
+ <parameter>access</parameter> <type>timestamp with time zone</type>,
<parameter>modification</parameter> <type>timestamp with time zone</type>,
+ <parameter>change</parameter> <type>timestamp with time zone</type>,
+ <parameter>creation</parameter> <type>timestamp with time zone</type>,
<parameter>isdir</parameter> <type>boolean</type> )
</para>
<para>
For each file in the server's log directory,
- return the file's name, size, last modification time (mtime), and a boolean
- indicating if the file is a directory.
+ return the file's name, along with the metadata columns returned by
+ <function>pg_stat_file</function>.
Filenames beginning with a dot and special file types are excluded.
</para>
<para>
@@ -25835,13 +25844,16 @@ LATERAL pg_ls_dir_recurse(dir) AS a;
<returnvalue>setof record</returnvalue>
( <parameter>name</parameter> <type>text</type>,
<parameter>size</parameter> <type>bigint</type>,
+ <parameter>access</parameter> <type>timestamp with time zone</type>,
<parameter>modification</parameter> <type>timestamp with time zone</type>,
+ <parameter>change</parameter> <type>timestamp with time zone</type>,
+ <parameter>creation</parameter> <type>timestamp with time zone</type>,
<parameter>isdir</parameter> <type>boolean</type> )
</para>
<para>
For each file in the server's write-ahead log (WAL) directory, list the
- file's name, size, last modification time (mtime), and a boolean
- indicating if the file is a directory.
+ file's name along with the metadata columns returned by
+ <function>pg_stat_file</function>.
Filenames beginning with a dot and special files types are excluded.
</para>
<para>
@@ -25860,14 +25872,17 @@ LATERAL pg_ls_dir_recurse(dir) AS a;
<returnvalue>setof record</returnvalue>
( <parameter>name</parameter> <type>text</type>,
<parameter>size</parameter> <type>bigint</type>,
+ <parameter>access</parameter> <type>timestamp with time zone</type>,
<parameter>modification</parameter> <type>timestamp with time zone</type>,
+ <parameter>change</parameter> <type>timestamp with time zone</type>,
+ <parameter>creation</parameter> <type>timestamp with time zone</type>,
<parameter>isdir</parameter> <type>boolean</type> )
</para>
<para>
For each file in the server's WAL archive status directory
- (<filename>pg_wal/archive_status</filename>), list the file's
- name, size, last modification time (mtime), and a boolean indicating if
- the file is a directory.
+ (<filename>pg_wal/archive_status</filename>), list the file's name
+ along with the metadata columns returned by
+ <function>pg_stat_file</function>.
Filenames beginning with a dot and special file types are excluded.
</para>
<para>
@@ -25887,13 +25902,17 @@ LATERAL pg_ls_dir_recurse(dir) AS a;
<returnvalue>setof record</returnvalue>
( <parameter>name</parameter> <type>text</type>,
<parameter>size</parameter> <type>bigint</type>,
+ <parameter>access</parameter> <type>timestamp with time zone</type>,
<parameter>modification</parameter> <type>timestamp with time zone</type>,
+ <parameter>change</parameter> <type>timestamp with time zone</type>,
+ <parameter>creation</parameter> <type>timestamp with time zone</type>,
<parameter>isdir</parameter> <type>boolean</type> )
</para>
<para>
For each file in the temporary directory within the given
- <parameter>tablespace</parameter>, return the file's name, size, last
- modification time (mtime) and a boolean indicating if the file is a directory.
+ <parameter>tablespace</parameter>, list the file's name
+ along with the metadata columns returned by
+ <function>pg_stat_file</function>.
Directories are used for temporary files shared by parallel processes.
If <parameter>tablespace</parameter> is not provided, the
<literal>pg_default</literal> tablespace is examined.
diff --git a/src/backend/utils/adt/genfile.c b/src/backend/utils/adt/genfile.c
index 35fe4d7cc1..20b948b746 100644
--- a/src/backend/utils/adt/genfile.c
+++ b/src/backend/utils/adt/genfile.c
@@ -36,6 +36,8 @@
#include "utils/syscache.h"
#include "utils/timestamp.h"
+static void tuple_from_stat(struct stat *fst, const char *path, Datum *values,
+ bool *nulls);
static Datum pg_ls_dir_files(FunctionCallInfo fcinfo, const char *dir, int flags);
#define LS_DIR_ISDIR (1<<0) /* Show column: isdir */
@@ -397,6 +399,28 @@ pg_read_binary_file_all(PG_FUNCTION_ARGS)
return pg_read_binary_file(fcinfo);
}
+/*
+ * Populate values and nulls from fst and path.
+ * Used for pg_stat_file() and pg_stat_dir_files()
+ * nulls is assumed to have been zerod.
+ */
+static void
+tuple_from_stat(struct stat *fst, const char *path, Datum *values, bool *nulls)
+{
+ values[0] = Int64GetDatum((int64) fst->st_size);
+ values[1] = TimestampTzGetDatum(time_t_to_timestamptz(fst->st_atime));
+ values[2] = TimestampTzGetDatum(time_t_to_timestamptz(fst->st_mtime));
+ /* Unix has file status change time, while Win32 has creation time */
+#if !defined(WIN32) && !defined(__CYGWIN__)
+ values[3] = TimestampTzGetDatum(time_t_to_timestamptz(fst->st_ctime));
+ nulls[4] = true;
+#else
+ nulls[3] = true;
+ values[4] = TimestampTzGetDatum(time_t_to_timestamptz(fst->st_ctime));
+#endif
+ values[5] = BoolGetDatum(S_ISDIR(fst->st_mode));
+}
+
/*
* stat a file
*/
@@ -407,7 +431,7 @@ pg_stat_file(PG_FUNCTION_ARGS)
char *filename;
struct stat fst;
Datum values[6];
- bool isnull[6];
+ bool nulls[6];
HeapTuple tuple;
TupleDesc tupdesc;
bool missing_ok = false;
@@ -447,27 +471,9 @@ pg_stat_file(PG_FUNCTION_ARGS)
"isdir", BOOLOID, -1, 0);
BlessTupleDesc(tupdesc);
- memset(isnull, false, sizeof(isnull));
-
- values[0] = Int64GetDatum((int64) fst.st_size);
- values[1] = TimestampTzGetDatum(time_t_to_timestamptz(fst.st_atime));
- values[2] = TimestampTzGetDatum(time_t_to_timestamptz(fst.st_mtime));
- /* Unix has file status change time, while Win32 has creation time */
-#if !defined(WIN32) && !defined(__CYGWIN__)
- values[3] = TimestampTzGetDatum(time_t_to_timestamptz(fst.st_ctime));
- isnull[4] = true;
-#else
- isnull[3] = true;
- values[4] = TimestampTzGetDatum(time_t_to_timestamptz(fst.st_ctime));
-#endif
- values[5] = BoolGetDatum(S_ISDIR(fst.st_mode));
-#ifdef WIN32
- /* Links should have isdir=false */
- if (pgwin32_is_junction(filename))
- values[5] = BoolGetDatum(false);
-#endif
-
- tuple = heap_form_tuple(tupdesc, values, isnull);
+ memset(nulls, false, sizeof(nulls));
+ tuple_from_stat(&fst, filename, values, nulls);
+ tuple = heap_form_tuple(tupdesc, values, nulls);
pfree(filename);
@@ -608,8 +614,8 @@ pg_ls_dir_files(FunctionCallInfo fcinfo, const char *dir, int flags)
while ((de = ReadDir(dirdesc, dir)) != NULL)
{
- Datum values[4];
- bool nulls[4];
+ Datum values[7];
+ bool nulls[7];
char path[MAXPGPATH * 2];
struct stat attrib;
@@ -648,23 +654,10 @@ pg_ls_dir_files(FunctionCallInfo fcinfo, const char *dir, int flags)
continue;
}
+ memset(nulls, false, sizeof(nulls));
values[0] = CStringGetTextDatum(de->d_name);
if (flags & LS_DIR_METADATA)
- {
- values[1] = Int64GetDatum((int64) attrib.st_size);
- values[2] = TimestampTzGetDatum(time_t_to_timestamptz(attrib.st_mtime));
- if (flags & LS_DIR_ISDIR)
- {
- values[3] = BoolGetDatum(S_ISDIR(attrib.st_mode));
-#ifdef WIN32
- /* Links should have isdir=false */
- if (pgwin32_is_junction(path))
- values[3] = BoolGetDatum(false);
-#endif
- }
- }
-
- memset(nulls, 0, sizeof(nulls));
+ tuple_from_stat(&attrib, path, 1+values, 1+nulls);
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 0235042e26..3f62aea9c9 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -10933,29 +10933,29 @@
{ oid => '3353', descr => 'list files in the log directory',
proname => 'pg_ls_logdir', procost => '10', prorows => '20', proretset => 't',
provolatile => 'v', prorettype => 'record', proargtypes => '',
- proallargtypes => '{text,int8,timestamptz,bool}', proargmodes => '{o,o,o,o}',
- proargnames => '{name,size,modification,isdir}', prosrc => 'pg_ls_logdir' },
+ proallargtypes => '{text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}', proargmodes => '{o,o,o,o,o,o,o}',
+ proargnames => '{name,size,access,modification,change,creation,isdir}', prosrc => 'pg_ls_logdir' },
{ oid => '3354', descr => 'list of files in the WAL directory',
proname => 'pg_ls_waldir', procost => '10', prorows => '20', proretset => 't',
provolatile => 'v', prorettype => 'record', proargtypes => '',
- proallargtypes => '{text,int8,timestamptz,bool}', proargmodes => '{o,o,o,o}',
- proargnames => '{name,size,modification,isdir}', prosrc => 'pg_ls_waldir' },
+ proallargtypes => '{text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}', proargmodes => '{o,o,o,o,o,o,o}',
+ proargnames => '{name,size,access,modification,change,creation,isdir}', prosrc => 'pg_ls_waldir' },
{ oid => '5031', descr => 'list of files in the archive_status directory',
proname => 'pg_ls_archive_statusdir', procost => '10', prorows => '20',
proretset => 't', provolatile => 'v', prorettype => 'record',
- proargtypes => '', proallargtypes => '{text,int8,timestamptz,bool}',
- proargmodes => '{o,o,o,o}', proargnames => '{name,size,modification,isdir}',
+ proargtypes => '', proallargtypes => '{text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}',
+ proargmodes => '{o,o,o,o,o,o,o}', proargnames => '{name,size,access,modification,change,creation,isdir}',
prosrc => 'pg_ls_archive_statusdir' },
{ oid => '5029', descr => 'list files in the pgsql_tmp directory',
proname => 'pg_ls_tmpdir', procost => '10', prorows => '20', proretset => 't',
provolatile => 'v', prorettype => 'record', proargtypes => '',
- proallargtypes => '{text,int8,timestamptz,bool}', proargmodes => '{o,o,o,o}',
- proargnames => '{name,size,modification,isdir}', prosrc => 'pg_ls_tmpdir_noargs' },
+ proallargtypes => '{text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}', proargmodes => '{o,o,o,o,o,o,o}',
+ proargnames => '{name,size,access,modification,change,creation,isdir}', prosrc => 'pg_ls_tmpdir_noargs' },
{ oid => '5030', descr => 'list files in the pgsql_tmp directory',
proname => 'pg_ls_tmpdir', procost => '10', prorows => '20', proretset => 't',
provolatile => 'v', prorettype => 'record', proargtypes => 'oid',
- proallargtypes => '{oid,text,int8,timestamptz,bool}', proargmodes => '{i,o,o,o,o}',
- proargnames => '{tablespace,name,size,modification,isdir}',
+ proallargtypes => '{oid,text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}', proargmodes => '{i,o,o,o,o,o,o,o}',
+ proargnames => '{tablespace,name,size,access,modification,change,creation,isdir}',
prosrc => 'pg_ls_tmpdir_1arg' },
{ oid => '9147', descr => 'check pages of a relation',
proname => 'pg_relation_check_pages', procost => '10000', prorows => '20',
@@ -10967,21 +10967,21 @@
{ oid => '9979', descr => 'list directory with metadata',
proname => 'pg_ls_dir_metadata', procost => '10', prorows => '20', proretset => 't',
provolatile => 'v', prorettype => 'record', proargtypes => 'text bool bool',
- proallargtypes => '{text,bool,bool,text,int8,timestamptz,bool}', proargmodes => '{i,i,i,o,o,o,o}',
- proargnames => '{dirname,missing_ok,include_dot_dirs,filename,size,modification,isdir}',
+ proallargtypes => '{text,bool,bool,text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}', proargmodes => '{i,i,i,o,o,o,o,o,o,o}',
+ proargnames => '{dirname,missing_ok,include_dot_dirs,filename,size,access,modification,change,creation,isdir}',
prosrc => 'pg_ls_dir_metadata' },
{ oid => '9980', descr => 'list directory with metadata',
proname => 'pg_ls_dir_metadata', procost => '10', prorows => '20', proretset => 't',
provolatile => 'v', prorettype => 'record', proargtypes => 'text',
- proallargtypes => '{text,text,int8,timestamptz,bool}', proargmodes => '{i,o,o,o,o}',
- proargnames => '{dirname,filename,size,modification,isdir}',
+ proallargtypes => '{text,text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}', proargmodes => '{i,o,o,o,o,o,o,o}',
+ proargnames => '{dirname,filename,size,access,modification,change,creation,isdir}',
prosrc => 'pg_ls_dir_metadata_1arg' },
{ oid => '9981', descr => 'list all files in a directory recursively',
proname => 'pg_ls_dir_recurse', prorows => '10000', proretset => 't',
provolatile => 'v', prorettype => 'record', proargtypes => 'text',
- proallargtypes => '{text,text,text,int8,timestamptz,bool}',
- proargnames => '{dirname,path,filename,size,modification,isdir}', proargmodes => '{i,o,o,o,o,o}',
- prolang => 'sql', prosrc => "with recursive ls as (select dirname as path, * from pg_ls_dir_metadata(dirname, false, false) union all select coalesce(nullif(parent.path,'.')||'/','')||parent.filename, a.filename, a.size, a.modification, a.isdir from ls as parent, lateral pg_ls_dir_metadata(parent.path||'/'||parent.filename, false, false) as a where parent.isdir) select * from ls" },
+ proallargtypes => '{text,text,text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool}',
+ proargnames => '{dirname,path,filename,size,access,modification,change,creation,isdir}', proargmodes => '{i,o,o,o,o,o,o,o,o}',
+ prolang => 'sql', prosrc => "with recursive ls as (select dirname as path, * from pg_ls_dir_metadata(dirname, false, false) union all select coalesce(nullif(parent.path,'.')||'/','')||parent.filename, a.filename, a.size, a.access, a.modification, a.change, a.creation, a.isdir from ls as parent, lateral pg_ls_dir_metadata(parent.path||'/'||parent.filename, false, false) as a where parent.isdir) select * from ls" },
# hash partitioning constraint function
{ oid => '5028', descr => 'hash partition CHECK constraint',
diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out
index 302f348a6d..4be27fe21e 100644
--- a/src/test/regress/expected/misc_functions.out
+++ b/src/test/regress/expected/misc_functions.out
@@ -157,8 +157,8 @@ select count(*) > 0 as ok from (select pg_ls_waldir()) ss;
-- Test not-run-to-completion cases.
select * from pg_ls_waldir() limit 0;
- name | size | modification | isdir
-------+------+--------------+-------
+ name | size | access | modification | change | creation | isdir
+------+------+--------+--------------+--------+----------+-------
(0 rows)
select count(*) > 0 as ok from (select * from pg_ls_waldir() limit 1) ss;
@@ -222,8 +222,8 @@ ERROR: could not open directory "does not exist": No such file or directory
-- This tests the missing_ok parameter, which causes pg_ls_tmpdir to succeed even if the tmpdir doesn't exist yet
-- The name='' condition is never true, so the function runs to completion but returns zero rows.
select * from pg_ls_tmpdir() where name='Does not exist';
- name | size | modification | isdir
-------+------+--------------+-------
+ name | size | access | modification | change | creation | isdir
+------+------+--------+--------------+--------+----------+-------
(0 rows)
select filename, isdir from pg_ls_dir_metadata('.') where filename='.';
@@ -239,8 +239,8 @@ select filename, isdir from pg_ls_dir_metadata('.', false, false) where filename
-- Check that expected columns are present
select * from pg_ls_dir_metadata('.') limit 0;
- filename | size | modification | isdir
-----------+------+--------------+-------
+ filename | size | access | modification | change | creation | isdir
+----------+------+--------+--------------+--------+----------+-------
(0 rows)
-- Check that we at least succeed in recursing once, and that we don't show the leading dir prefix
@@ -252,8 +252,8 @@ select path, filename, isdir from pg_ls_dir_recurse('.') where isdir and path='p
-- Check that expected columns are present
select * from pg_ls_dir_recurse('.') limit 0;
- path | filename | size | modification | isdir
-------+----------+------+--------------+-------
+ path | filename | size | access | modification | change | creation | isdir
+------+----------+------+--------+--------------+--------+----------+-------
(0 rows)
--
diff --git a/src/test/regress/output/tablespace.source b/src/test/regress/output/tablespace.source
index ba9a3fe29a..1e1e02b589 100644
--- a/src/test/regress/output/tablespace.source
+++ b/src/test/regress/output/tablespace.source
@@ -17,15 +17,15 @@ CREATE TABLESPACE regress_tblspace LOCATION '@testtablespace@';
-- The name='' condition is never true, so the function runs to completion but returns zero rows.
-- The query is written to ERROR if the tablespace doesn't exist, rather than silently failing to call pg_ls_tmpdir()
SELECT c.* FROM (SELECT oid FROM pg_tablespace b WHERE b.spcname='regress_tblspace' UNION SELECT 0 ORDER BY 1 DESC LIMIT 1) AS b , pg_ls_tmpdir(oid) AS c WHERE c.name='Does not exist';
- name | size | modification | isdir
-------+------+--------------+-------
+ name | size | access | modification | change | creation | isdir
+------+------+--------+--------------+--------+----------+-------
(0 rows)
-- This tests the missing_ok parameter. If that's not functioning, this would ERROR if the logdir doesn't exist yet.
-- The name='' condition is never true, so the function runs to completion but returns zero rows.
SELECT * FROM pg_ls_logdir() WHERE name='Does not exist';
- name | size | modification | isdir
-------+------+--------------+-------
+ name | size | access | modification | change | creation | isdir
+------+------+--------+--------------+--------+----------+-------
(0 rows)
-- try setting and resetting some properties for the new tablespace
--
2.17.0
--d6Gm4EdcadzBjdND
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v22-0010-pg_ls_-pg_stat_file-to-show-file-type.patch"
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Contradictory behavior of array_agg(distinct) aggregate.
@ 2024-12-04 07:20 Konstantin Knizhnik <[email protected]>
0 siblings, 1 reply; 3+ messages in thread
From: Konstantin Knizhnik @ 2024-12-04 07:20 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: pgsql-hackers
On 04/12/2024 9:03 am, Tom Lane wrote:
> Konstantin Knizhnik <[email protected]> writes:
>> postgres=# create table t(x integer unique);
>> CREATE TABLE
>> postgres=# insert into t values (null),(null);
>> INSERT 0 2
>> postgres=# select count(distinct x) from t;
>> count
>> -------
>> 0
>> (1 row)
>> postgres=# select array_agg(distinct x) from t;
>> array_agg
>> -----------
>> {NULL}
>> (1 row)
>> postgres=# select array_agg(x) from t;
>> array_agg
>> -------------
>> {NULL,NULL}
>> (1 row)
> I see nothing contradictory here. "array_agg(distinct x)"
> combines the two NULLs into one, which is the normal
> behavior of DISTINCT.
Sorry.
It is actually inconsistency in basic SQL model in interpretation of
NULL by UNIQUE and DISTINCT, and array_agg just follows this rule.
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Contradictory behavior of array_agg(distinct) aggregate.
@ 2024-12-04 10:25 Dagfinn Ilmari Mannsåker <[email protected]>
parent: Konstantin Knizhnik <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Dagfinn Ilmari Mannsåker @ 2024-12-04 10:25 UTC (permalink / raw)
To: Konstantin Knizhnik <[email protected]>; +Cc: Tom Lane <[email protected]>; pgsql-hackers
Konstantin Knizhnik <[email protected]> writes:
> On 04/12/2024 9:03 am, Tom Lane wrote:
>> Konstantin Knizhnik <[email protected]> writes:
>>> postgres=# create table t(x integer unique);
>>> CREATE TABLE
>>> postgres=# insert into t values (null),(null);
>>> INSERT 0 2
>>> postgres=# select count(distinct x) from t;
>>> count
>>> -------
>>> 0
>>> (1 row)
>>> postgres=# select array_agg(distinct x) from t;
>>> array_agg
>>> -----------
>>> {NULL}
>>> (1 row)
>>> postgres=# select array_agg(x) from t;
>>> array_agg
>>> -------------
>>> {NULL,NULL}
>>> (1 row)
>> I see nothing contradictory here. "array_agg(distinct x)"
>> combines the two NULLs into one, which is the normal
>> behavior of DISTINCT.
>
>
> Sorry.
> It is actually inconsistency in basic SQL model in interpretation of
> NULL by UNIQUE and DISTINCT, and array_agg just follows this rule.
The behaviour of DISTINCT in aggregates matches the behaviour of the IS
(NOT) DISTINCT FROM predicate, which considers NULLs NOT DISTINCT from
eachother.
UNIQUE constraints leave it implementation-defined whether NULLs are
considered distinct (PostgreSQL defaults to NULLS DISTINCT), but that
can be overridden in the constraint definition.
- ilmari
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2020-03-10 02:56 [PATCH v22 09/10] pg_ls_*dir to return all the metadata from pg_stat_file.. Justin Pryzby <[email protected]>
2024-12-04 07:20 Re: Contradictory behavior of array_agg(distinct) aggregate. Konstantin Knizhnik <[email protected]>
2024-12-04 10:25 ` Re: Contradictory behavior of array_agg(distinct) aggregate. Dagfinn Ilmari Mannsåker <[email protected]>
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