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* Re: [HACKERS] Proposal: generic WAL compression
@ 2017-11-16 17:31 Antonin Houska <[email protected]>
1 sibling, 3 replies; 14+ messages in thread
From: Antonin Houska @ 2017-11-16 17:31 UTC (permalink / raw)
To: pgsql-hackers; +Cc: Oleg Ivanov <[email protected]>
Oleg Ivanov <[email protected]> wrote:
> In order to overcome that issue, I would like to propose the patch, which
> provides possibility to use another approach of the WAL record
> construction.
After having spent several hours reviewing this patch I dare to send the
following comments:
* writeToPtr() and readFromPtr() are applied to the existing code. I think
this is a reason for a separate diff, to be applied before the actual patch.
BTW, if you're going to do any refactoring of the existing code, I think the
"Begin" and "Start" words should be used consistently, see "fragmentBegin" vs
"validStart" in computeRegionBaseDelta().
* What's the reason for changing FRAGMENT_HEADER_SIZE ? I see no change in
the data layout that writeFragment() produces.
* alignRegions()
** typo in the prologue: "mismathing".
** "An O(ND) Difference Algorithm and Its Variations" - I think the reference
should contain more information, e.g. name of the author(s). I think I even
saw URLs to scientific papers in the PG source but I'm not 100% sure right
now.
** As for the algorithm itself: Although I didn't have enough patience (and
time) to follow it in every detail for this first review, I think I can
imagine what it is about. Yet I think reading would be easier if the
concepts of alignment and "diff delta" were depicted in the comments,
perhaps using some sort of "ASCII graphics".
** DiffDeltaOperations enumeration: the individual values should be described.
* computeRegionDiffDelta()
** Does "previous delta" in one of the comments refer to "base delta",
i.e. the delta computation w/o your patch? If so, the comment should
mention it explicitly.
** If you use Min() to initialize the for-loop, it'd be more consistent if you
also used Max() when checking the limits:
for (i = Min(validStart, targetStart); i < Max(validEnd, targetEnd); ++i)
And similarly you can simplify the body of the loop.
* computeDelta()
As the expresssion
*((bool *) pageData->delta)
is used more than once, I think a separate (bool *) variable should be used.
--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2017-11-17 12:02 Arthur Silva <[email protected]>
1 sibling, 0 replies; 14+ messages in thread
From: Arthur Silva @ 2017-11-17 12:02 UTC (permalink / raw)
To: Oleg Ivanov <[email protected]>; +Cc: pgsql-hackers
I wonder if the algorithm could be changed to operate with units of 2 or 4
bytes (instead of 1).
Since the algorithm speed is essentially doubled/quadrupled it could yield
a better runtime/compression trade-off.
Does that make sense?
--
Arthur Silva
On Wed, Nov 1, 2017 at 12:43 AM, Oleg Ivanov <[email protected]>
wrote:
> Hackers,
>
> a few years ago generic WAL was proposed by Alexander Korotkov (
> https://www.postgresql.org/message-id/flat/CAPpHfdsXwZmojm6
> Dx%2BTJnpYk27kT4o7Ri6X_4OSWcByu1Rm%2BVA%40mail.gmail.com#CAP
> [email protected]). and was
> committed into PostgreSQL 9.6.
> One of the generic WAL advantages is the common interface for safe
> interaction with WAL for modules and extensions. The interface allows
> module to register the page, then change it, and then generic WAL generates
> and writes into xlog the algorithm of changing the old version of page into
> the new one. In the case of crash and recovery this algorithm may be
> applied.
>
> Bloom and RUM indexes use generic WAL. The issue is that the generic
> algorithm of turning the old page into the new one is not optimal in the
> sense of record size in xlog. Now the main idea of the approach is to find
> all positions in the page where new version is different from the original
> one and write these changes into xlog. It works well if the page was
> rewritten completely or if only a few bytes have been changed.
> Nevertheless, this approach produces too large WAL record in the case of
> inserting or deleting a few bytes into the page. In this case there are
> almost no position where the old version and the new one are equal, so the
> record size is near the page size, but actual amount of changes in the page
> is small. This is exactly what happens often in RUM indexes.
>
> In order to overcome that issue, I would like to propose the patch, which
> provides possibility to use another approach of the WAL record
> construction. If another approach fails to make a short enough record, it
> rolls back to the original approach. The main idea of another approach is
> not to perform bytewise comparison of pages, but finding the minimal
> editing distance between two pages and the corresponding editing algorithm.
> In the general case, finding editing distance takes O(N^2) time and memory.
> But there is also an algorithm which requires only O(ND) time and O(D^2)
> memory, where D is the editing distance between two sequences. Also for
> given D algorithm may show that the minimal editing distance between two
> sequences is more than D in the same amount of time and memory.
>
> The special case of this algorithm which does not consider replace
> operations is described in the paper (http://www.xmailserver.org/diff2.pdf).
> The version of this algorithm which consumes O(ND) time and O(N) memory is
> used in diff console command, but for our purposes we don't need to
> increase the constant for the time in order to decrease memory complexity.
> For RUM indexes we usually have small enough editing distance (less than
> 64), so D^2 is not too much to store.
>
> The results of experiments:
>
> +------------------------------+----------------+-----------
> -----+----------------+----------------+
> | Name | WAL_diff(MB) | WAL_orig(MB) |
> Time_diff(s) | Time_orig(s) |
> +------------------------------+----------------+-----------
> -----+----------------+----------------+
> | rum: make installcheck | 38.9 | 82.5 | 4.37 |
> 4.16 |
> +------------------------------+----------------+-----------
> -----+----------------+----------------+
> | bloom: make installcheck | 1.0 | 1.0 | 0.66 |
> 0.53 |
> +------------------------------+----------------+-----------
> -----+----------------+----------------+
> | test00.sql | 20.5 | 51.0 | 1.86 |
> 1.41 |
> +------------------------------+----------------+-----------
> -----+----------------+----------------+
> | test01.sql | 207.1 | 219.7 | 8.06 | 6.89
> |
> +------------------------------+----------------+-----------
> -----+----------------+----------------+
>
> We can see that the patch provides a little slowdown, but compresses
> generic WAL efficiently for RUM index. Also I'm going to do a few more
> experiments on this patch with another data.
>
> The patch was tested on Lubuntu 14.04, but should not contain any
> platform-specific items. The patch, the files and scripts for doing the
> experiments and performance tests are attached.
>
> Oleg Ivanov
> Postgres Professional
> The Russian PostgreSQL Company
>
>
> --
> Sent via pgsql-hackers mailing list ([email protected])
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-hackers
>
>
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2017-11-20 07:49 Antonin Houska <[email protected]>
parent: Antonin Houska <[email protected]>
2 siblings, 1 reply; 14+ messages in thread
From: Antonin Houska @ 2017-11-20 07:49 UTC (permalink / raw)
To: Oleg Ivanov <[email protected]>; +Cc: pgsql-hackers
Antonin Houska <[email protected]> wrote:
> Oleg Ivanov <[email protected]> wrote:
>
> > In order to overcome that issue, I would like to propose the patch, which
> > provides possibility to use another approach of the WAL record
> > construction.
>
> After having spent several hours reviewing this patch I dare to send the
> following comments:
One more idea:
I think the metadata (ALIGN_GAP) should be stored separate from the actual
data so that you can use memcpy() instead of this loop:
while (i < j)
{
char c = targetRegionAligned[i++];
writeToPtr(ptr, c);
}
--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2017-11-30 02:40 Michael Paquier <[email protected]>
parent: Antonin Houska <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Michael Paquier @ 2017-11-30 02:40 UTC (permalink / raw)
To: Antonin Houska <[email protected]>; +Cc: Oleg Ivanov <[email protected]>; pgsql-hackers
On Mon, Nov 20, 2017 at 4:49 PM, Antonin Houska <[email protected]> wrote:
> One more idea:
>
> I think the metadata (ALIGN_GAP) should be stored separate from the actual
> data so that you can use memcpy() instead of this loop:
>
> while (i < j)
> {
> char c = targetRegionAligned[i++];
>
> writeToPtr(ptr, c);
> }
Moved to next CF per lack of reviews. The patch still applies.
Oleg, I would recommend as well that you do more patch reviews. Let's
not forget that for one patch submitted you should review one patch
with a somewhat equal difficulty, and yours is quite specialized.
--
Michael
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2018-01-22 21:37 Stephen Frost <[email protected]>
parent: Antonin Houska <[email protected]>
2 siblings, 1 reply; 14+ messages in thread
From: Stephen Frost @ 2018-01-22 21:37 UTC (permalink / raw)
To: Antonin Houska <[email protected]>; +Cc: pgsql-hackers; Oleg Ivanov <[email protected]>
Oleg,
I'm not really sure why this is still in Needs Review as a review was
posted and I don't see any follow-up. I've changed this to be Waiting
for Author.
* Antonin Houska ([email protected]) wrote:
> Oleg Ivanov <[email protected]> wrote:
>
> > In order to overcome that issue, I would like to propose the patch, which
> > provides possibility to use another approach of the WAL record
> > construction.
>
> After having spent several hours reviewing this patch I dare to send the
> following comments:
Thanks for the review Antonin!
> * writeToPtr() and readFromPtr() are applied to the existing code. I think
> this is a reason for a separate diff, to be applied before the actual patch.
I'm not really a fan of using these, for my 2c. I'm not sure how others
feel, but having these macros which change one of the arguments to the
macro (by advancing the pointer) doesn't result in a net improvement to
readability for me.
The other review comments also seem pretty reasonable to me.
Thanks!
Stephen
Attachments:
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^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: Re: [HACKERS] Proposal: generic WAL compression
@ 2018-02-07 15:31 David Steele <[email protected]>
parent: Stephen Frost <[email protected]>
0 siblings, 1 reply; 14+ messages in thread
From: David Steele @ 2018-02-07 15:31 UTC (permalink / raw)
To: Oleg Ivanov <[email protected]>; +Cc: Stephen Frost <[email protected]>; Antonin Houska <[email protected]>; pgsql-hackers
Hi Oleg,
On 1/22/18 4:37 PM, Stephen Frost wrote:
> Oleg,
>
> I'm not really sure why this is still in Needs Review as a review was
> posted and I don't see any follow-up. I've changed this to be Waiting
> for Author.
>
> * Antonin Houska ([email protected]) wrote:
>> Oleg Ivanov <[email protected]> wrote:
>>
>>> In order to overcome that issue, I would like to propose the patch, which
>>> provides possibility to use another approach of the WAL record
>>> construction.
>>
>> After having spent several hours reviewing this patch I dare to send the
>> following comments:
>
> Thanks for the review Antonin!
>
>> * writeToPtr() and readFromPtr() are applied to the existing code. I think
>> this is a reason for a separate diff, to be applied before the actual patch.
>
> I'm not really a fan of using these, for my 2c. I'm not sure how others
> feel, but having these macros which change one of the arguments to the
> macro (by advancing the pointer) doesn't result in a net improvement to
> readability for me.
>
> The other review comments also seem pretty reasonable to me.
This proposal is still in need of review and hasn't really gotten it in
the last few CFs.
Since the feature does not seem like a good fit for the last CF of PG11
I am marking it Returned with Feedback.
Regards,
--
-David
[email protected]
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2018-02-07 18:02 Markus Nullmeier <[email protected]>
parent: David Steele <[email protected]>
0 siblings, 2 replies; 14+ messages in thread
From: Markus Nullmeier @ 2018-02-07 18:02 UTC (permalink / raw)
To: David Steele <[email protected]>; pgsql-hackers; +Cc: Oleg Ivanov <[email protected]>; Stephen Frost <[email protected]>; Antonin Houska <[email protected]>
Hi David,
On 07/02/18 18:31, David Steele wrote:
> This proposal is still in need of review and hasn't really gotten it in
> the last few CFs.
Agreed.
> Since the feature does not seem like a good fit for the last CF of PG11
> I am marking it Returned with Feedback.
Is there any chance that it may be still resubmitted / reopened for the
March CF?
Actually right now I am in the process of reviewing it, for it would be
really useful for my "OUZO" project (a fork of the RUM access method).
One general comment I can already make is that enabling compression
should be made optional, which appears to be a small and easy addition
to the generic WAL API.
Best regards,
--
Markus Nullmeier http://www.g-vo.org
German Astrophysical Virtual Observatory (GAVO)
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2018-02-07 18:42 Stephen Frost <[email protected]>
parent: Markus Nullmeier <[email protected]>
1 sibling, 1 reply; 14+ messages in thread
From: Stephen Frost @ 2018-02-07 18:42 UTC (permalink / raw)
To: Markus Nullmeier <[email protected]>; +Cc: David Steele <[email protected]>; pgsql-hackers; Oleg Ivanov <[email protected]>; Antonin Houska <[email protected]>
Greetings,
* Markus Nullmeier ([email protected]) wrote:
> On 07/02/18 18:31, David Steele wrote:
>
> > This proposal is still in need of review and hasn't really gotten it in
> > the last few CFs.
>
> Agreed.
>
> > Since the feature does not seem like a good fit for the last CF of PG11
> > I am marking it Returned with Feedback.
>
> Is there any chance that it may be still resubmitted / reopened for the
> March CF?
Of course, you're certainly welcome to resubmit it to a future CF. As
we're getting close to the end of this release cycle, I tend to think it
would be appropriate to submit it for the post-11 CF rather than the one
in March.
> Actually right now I am in the process of reviewing it, for it would be
> really useful for my "OUZO" project (a fork of the RUM access method).
Glad to hear that you're continuing to work on it.
> One general comment I can already make is that enabling compression
> should be made optional, which appears to be a small and easy addition
> to the generic WAL API.
The question would be- is there a way for us to determine when it should
be enabled or not enabled, or do we have to ask the user to tell us?
Asking the user is something we'd really not do unless we absolutely
have to. Much better is if we can figure out when it's best to enable
or disable (or use/not use) based on some criteria and do so
automatically.
Thanks!
Stephen
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^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2018-02-08 16:17 Markus Nullmeier <[email protected]>
parent: Stephen Frost <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Markus Nullmeier @ 2018-02-08 16:17 UTC (permalink / raw)
To: Stephen Frost <[email protected]>; Oleg Ivanov <[email protected]>; +Cc: pgsql-hackers; Antonin Houska <[email protected]>
On 07/02/18 19:42, Stephen Frost wrote:
>> really useful for my "OUZO" project (a fork of the RUM access method).
>
> Glad to hear that you're continuing to work on it.
Yes, it will be available on Github eventually.
>> One general comment I can already make is that enabling compression
>> should be made optional, which appears to be a small and easy addition
>> to the generic WAL API.
>
> The question would be- is there a way for us to determine when it should
> be enabled or not enabled, or do we have to ask the user to tell us?
My suggestion would be adding something like
#define GENERIC_XLOG_MOVE_DETECT_ON 0x0002 /* search for moved
parts of page image */
#define GENERIC_XLOG_MOVE_DETECT_OFF 0x0004 /* do not search for
moved parts of page image */
This would be used for the 'flags' argument of GenericXLogRegisterBuffer(),
allowing code using generic WAL (such as custom access methods) to
control this kind of compression on a per buffer basis, if need be.
Then it would be up to the author of any extension relying on generic
WAL to decide if and how the user will be given control of WAL
compression.
However,
> Asking the user is something we'd really not do unless we absolutely
> have to. Much better is if we can figure out when it's best to enable
> or disable (or use/not use) based on some criteria and do so
> automatically.
this is a point I did not think of before :-) Probably a logical
choice would be having "GENERIC_XLOG_MOVE_DETECT" default to true
for a 'wal_level' value of 'replica' (the default setting nowadays)
or higher, and default to false for 'minimal'.
In this way, generic WAL will be automatically compressed when it is
potentially stored for some longer time, or consuming network bandwidth.
--
Markus Nullmeier http://www.g-vo.org
German Astrophysical Virtual Observatory (GAVO)
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2018-02-17 07:31 Oleg Ivanov <[email protected]>
parent: Antonin Houska <[email protected]>
2 siblings, 0 replies; 14+ messages in thread
From: Oleg Ivanov @ 2018-02-17 07:31 UTC (permalink / raw)
To: Antonin Houska <[email protected]>; Arthur Silva <[email protected]>; Michael Paquier <[email protected]>; Stephen Frost <[email protected]>; Markus Nullmeier <[email protected]>; David Steele <[email protected]>; pgsql-hackers
Hello everyone!
Unfortunately, I faced the use case with RUM index, in which my patch
produced
enormously large time overhead (queries execution time is about 2 or 3 times
slower). Only now I finally managed to limit this overhead by 20% or
even make
it statistically insignificant on my HDD. Nevertheless, SSD evaluation
is still
required.
So I attach new test totat_test.sh script which includes the bad RUM use
case
and the new version of the patch.
Thanks everybody for review, it improved the patch a lot. The majority
of the
listed drawbacks were fixed, the others are discussed below.
On 11/16/2017 08:31 PM, Antonin Houska wrote:
> * writeToPtr() and readFromPtr() are applied to the existing code. I think
> this is a reason for a separate diff, to be applied before the actual patch.
Removed the existing code refactoring, that should be a separate patch
indeed.
> * What's the reason for changing FRAGMENT_HEADER_SIZE ? I see no change in
> the data layout that writeFragment() produces.
Diff delta has its own header which consists of one char and one int. To
make
this point more clear, I defined DIFF_DELTA_HEADER_SIZE and added
2 * DIFF_DELTA_HEADER_SIZE to MAX_DELTA_SIZE.
> ** "An O(ND) Difference Algorithm and Its Variations" - I think the reference
> should contain more information, e.g. name of the author(s). I think I even
> saw URLs to scientific papers in the PG source but I'm not 100% sure right
> now.
The reference to the paper contains much more information now.
> ** As for the algorithm itself: Although I didn't have enough patience (and
> time) to follow it in every detail for this first review, I think I can
> imagine what it is about. Yet I think reading would be easier if the
> concepts of alignment and "diff delta" were depicted in the comments,
> perhaps using some sort of "ASCII graphics".
I briefly described the main idea of the dynamical programming algorithm
in comments of alignRegions. It can be further refined if you think it is
still unclear now, but I'm afraid the detailed description will result
in just
copying the referred paper into the comments.
> ** DiffDeltaOperations enumeration: the individual values should be described.
>
>
> * computeRegionDiffDelta()
>
> ** Does "previous delta" in one of the comments refer to "base delta",
> i.e. the delta computation w/o your patch? If so, the comment should
> mention it explicitly.
>
> ** If you use Min() to initialize the for-loop, it'd be more consistent if you
> also used Max() when checking the limits:
>
> for (i = Min(validStart, targetStart); i < Max(validEnd, targetEnd); ++i)
>
> And similarly you can simplify the body of the loop.
I found that this part of code is unnecessary and deleted it.
On 11/17/2017 03:02 PM, Arthur Silva wrote:
> I wonder if the algorithm could be changed to operate with units of 2
> or 4 bytes (instead of 1).
> Since the algorithm speed is essentially doubled/quadrupled it could
> yield a better runtime/compression trade-off.
>
> Does that make sense?
This approach implies that we cannot detect data shift by one byte, for
example.
It is suitable for 2- or 4-bytes-aligned data, but looks not general enough.
On 01/23/2018 12:37 AM, Stephen Frost wrote:
>> * writeToPtr() and readFromPtr() are applied to the existing code. I think
>> this is a reason for a separate diff, to be applied before the actual patch.
> I'm not really a fan of using these, for my 2c. I'm not sure how others
> feel, but having these macros which change one of the arguments to the
> macro (by advancing the pointer) doesn't result in a net improvement to
> readability for me.
Sounds reasonable, but the patch uses such constructions as writeToPtr
rather
often. How do you feel about using writeToPtr(&ptr, data) which which more
explicitly indicates the first argument changing?
On 02/07/2018 09:02 PM, Markus Nullmeier wrote:
> One general comment I can already make is that enabling compression
> should be made optional, which appears to be a small and easy addition
> to the generic WAL API.
Now I'm working on this.I consider creation the function
GenericXLogRegisterBufferEx in addition to GenericXLogRegisterBuffer.
GenericXLogRegisterBufferEx will take a structure with parameters for diff
delta such as maximal alignment length, to which parts of page it must be
applied, etc. And GenericXLogRegisterBufferwill call
GenericXLogRegisterBufferEx with default parameters. This allows using
different compression settings for different indexes. What do you think
about
such solution?
# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
# name = value
#
# (The "=" is optional.) Whitespace may be used. Comments are introduced with
# "#" anywhere on a line. The complete list of parameter names and allowed
# values can be found in the PostgreSQL documentation.
#
# The commented-out settings shown in this file represent the default values.
# Re-commenting a setting is NOT sufficient to revert it to the default value;
# you need to reload the server.
#
# This file is read on server startup and when the server receives a SIGHUP
# signal. If you edit the file on a running system, you have to SIGHUP the
# server for the changes to take effect, run "pg_ctl reload", or execute
# "SELECT pg_reload_conf()". Some parameters, which are marked below,
# require a server shutdown and restart to take effect.
#
# Any parameter can also be given as a command-line option to the server, e.g.,
# "postgres -c log_connections=on". Some parameters can be changed at run time
# with the "SET" SQL command.
#
# Memory units: kB = kilobytes Time units: ms = milliseconds
# MB = megabytes s = seconds
# GB = gigabytes min = minutes
# TB = terabytes h = hours
# d = days
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable, represented here as ConfigDir.
#data_directory = 'ConfigDir' # use data in another directory
# (change requires restart)
#hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
# (change requires restart)
#ident_file = 'ConfigDir/pg_ident.conf' # ident configuration file
# (change requires restart)
# If external_pid_file is not explicitly set, no extra PID file is written.
#external_pid_file = '' # write an extra PID file
# (change requires restart)
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
#listen_addresses = 'localhost' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost'; use '*' for all
# (change requires restart)
#port = 5845 # (change requires restart)
max_connections = 100 # (change requires restart)
#superuser_reserved_connections = 3 # (change requires restart)
#unix_socket_directories = '/tmp' # comma-separated list of directories
# (change requires restart)
#unix_socket_group = '' # (change requires restart)
#unix_socket_permissions = 0777 # begin with 0 to use octal notation
# (change requires restart)
#bonjour = off # advertise server via Bonjour
# (change requires restart)
#bonjour_name = '' # defaults to the computer name
# (change requires restart)
# - Security and Authentication -
#authentication_timeout = 1min # 1s-600s
#ssl = off
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_dh_params_file = ''
#ssl_cert_file = 'server.crt'
#ssl_key_file = 'server.key'
#ssl_ca_file = ''
#ssl_crl_file = ''
#password_encryption = md5 # md5 or scram-sha-256
#db_user_namespace = off
#row_security = on
# GSSAPI using Kerberos
#krb_server_keyfile = ''
#krb_caseins_users = off
# - TCP Keepalives -
# see "man 7 tcp" for details
#tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds;
# 0 selects the system default
#tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds;
# 0 selects the system default
#tcp_keepalives_count = 0 # TCP_KEEPCNT;
# 0 selects the system default
#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------
# - Memory -
shared_buffers = 1024MB # min 128kB
# (change requires restart)
#huge_pages = try # on, off, or try
# (change requires restart)
#temp_buffers = 8MB # min 800kB
#max_prepared_transactions = 0 # zero disables the feature
# (change requires restart)
# Caution: it is not advisable to set max_prepared_transactions nonzero unless
# you actively intend to use prepared transactions.
#work_mem = 4MB # min 64kB
#maintenance_work_mem = 64MB # min 1MB
#replacement_sort_tuples = 150000 # limits use of replacement selection sort
#autovacuum_work_mem = -1 # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB # min 100kB
dynamic_shared_memory_type = posix # the default is the first option
# supported by the operating system:
# posix
# sysv
# windows
# mmap
# use none to disable dynamic shared memory
# (change requires restart)
# - Disk -
#temp_file_limit = -1 # limits per-process temp file space
# in kB, or -1 for no limit
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
# (change requires restart)
#shared_preload_libraries = '' # (change requires restart)
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0 # 0-100 milliseconds
#vacuum_cost_page_hit = 1 # 0-10000 credits
#vacuum_cost_page_miss = 10 # 0-10000 credits
#vacuum_cost_page_dirty = 20 # 0-10000 credits
#vacuum_cost_limit = 200 # 1-10000 credits
# - Background Writer -
bgwriter_delay = 20ms # 10-10000ms between rounds
bgwriter_lru_maxpages = 800 # 0-1000 max buffers written/round
bgwriter_lru_multiplier = 8.0 # 0-10.0 multiplier on buffers scanned/round
#bgwriter_flush_after = 512kB # measured in pages, 0 disables
# - Asynchronous Behavior -
#effective_io_concurrency = 1 # 1-1000; 0 disables prefetching
#max_worker_processes = 8 # (change requires restart)
#max_parallel_workers_per_gather = 2 # taken from max_parallel_workers
#max_parallel_workers = 8 # maximum number of max_worker_processes that
# can be used in parallel queries
#old_snapshot_threshold = -1 # 1min-60d; -1 disables; 0 is immediate
# (change requires restart)
#backend_flush_after = 0 # measured in pages, 0 disables
#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------
# - Settings -
wal_level = minimal # minimal, replica, or logical
# (change requires restart)
fsync = off # flush data to disk for crash safety
# (turning this off can cause
# unrecoverable data corruption)
synchronous_commit = off # synchronization level;
# off, local, remote_write, remote_apply, or on
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
# fdatasync (default on Linux)
# fsync
# fsync_writethrough
# open_sync
full_page_writes = off # recover from partial page writes
#wal_compression = off # enable compression of full-page writes
#wal_log_hints = off # also do full page writes of non-critical updates
# (change requires restart)
#wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers
# (change requires restart)
#wal_writer_delay = 200ms # 1-10000 milliseconds
#wal_writer_flush_after = 1MB # measured in pages, 0 disables
#commit_delay = 0 # range 0-100000, in microseconds
#commit_siblings = 5 # range 1-1000
# - Checkpoints -
checkpoint_timeout = 120min # range 30s-1d
max_wal_size = 8GB
min_wal_size = 1GB
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_flush_after = 256kB # measured in pages, 0 disables
#checkpoint_warning = 30s # 0 disables
# - Archiving -
#archive_mode = off # enables archiving; off, on, or always
# (change requires restart)
#archive_command = '' # command to use to archive a logfile segment
# placeholders: %p = path of file to archive
# %f = file name only
# e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
#archive_timeout = 0 # force a logfile segment switch after this
# number of seconds; 0 disables
#------------------------------------------------------------------------------
# REPLICATION
#------------------------------------------------------------------------------
# - Sending Server(s) -
# Set these on the master and on any standby that will send replication data.
max_wal_senders = 0 # max number of walsender processes
# (change requires restart)
#wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables
#wal_sender_timeout = 60s # in milliseconds; 0 disables
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
#track_commit_timestamp = off # collect timestamp of transaction commit
# (change requires restart)
# - Master Server -
# These settings are ignored on a standby server.
#synchronous_standby_names = '' # standby servers that provide sync rep
# method to choose sync standbys, number of sync standbys,
# and comma-separated list of application_name
# from standby(s); '*' = all
#vacuum_defer_cleanup_age = 0 # number of xacts by which cleanup is delayed
# - Standby Servers -
# These settings are ignored on a master server.
#hot_standby = on # "off" disallows queries during recovery
# (change requires restart)
#max_standby_archive_delay = 30s # max delay before canceling queries
# when reading WAL from archive;
# -1 allows indefinite delay
#max_standby_streaming_delay = 30s # max delay before canceling queries
# when reading streaming WAL;
# -1 allows indefinite delay
#wal_receiver_status_interval = 10s # send replies at least this often
# 0 disables
#hot_standby_feedback = off # send info from standby to prevent
# query conflicts
#wal_receiver_timeout = 60s # time that receiver waits for
# communication from master
# in milliseconds; 0 disables
#wal_retrieve_retry_interval = 5s # time to wait before retrying to
# retrieve WAL after a failed attempt
# - Subscribers -
# These settings are ignored on a publisher.
#max_logical_replication_workers = 4 # taken from max_worker_processes
# (change requires restart)
#max_sync_workers_per_subscription = 2 # taken from max_logical_replication_workers
#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on
# - Planner Cost Constants -
#seq_page_cost = 1.0 # measured on an arbitrary scale
#random_page_cost = 4.0 # same scale as above
#cpu_tuple_cost = 0.01 # same scale as above
#cpu_index_tuple_cost = 0.005 # same scale as above
#cpu_operator_cost = 0.0025 # same scale as above
#parallel_tuple_cost = 0.1 # same scale as above
#parallel_setup_cost = 1000.0 # same scale as above
#min_parallel_table_scan_size = 8MB
#min_parallel_index_scan_size = 512kB
#effective_cache_size = 4GB
# - Genetic Query Optimizer -
#geqo = on
#geqo_threshold = 12
#geqo_effort = 5 # range 1-10
#geqo_pool_size = 0 # selects default based on effort
#geqo_generations = 0 # selects default based on effort
#geqo_selection_bias = 2.0 # range 1.5-2.0
#geqo_seed = 0.0 # range 0.0-1.0
# - Other Planner Options -
#default_statistics_target = 100 # range 1-10000
#constraint_exclusion = partition # on, off, or partition
#cursor_tuple_fraction = 0.1 # range 0.0-1.0
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
# JOIN clauses
#force_parallel_mode = off
#------------------------------------------------------------------------------
# ERROR REPORTING AND LOGGING
#------------------------------------------------------------------------------
# - Where to Log -
#log_destination = 'stderr' # Valid values are combinations of
# stderr, csvlog, syslog, and eventlog,
# depending on platform. csvlog
# requires logging_collector to be on.
# This is used when logging to stderr:
#logging_collector = off # Enable capturing of stderr and csvlog
# into log files. Required to be on for
# csvlogs.
# (change requires restart)
# These are only used if logging_collector is on:
#log_directory = 'log' # directory where log files are written,
# can be absolute or relative to PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern,
# can include strftime() escapes
#log_file_mode = 0600 # creation mode for log files,
# begin with 0 to use octal notation
#log_truncate_on_rotation = off # If on, an existing log file with the
# same name as the new log file will be
# truncated rather than appended to.
# But such truncation only occurs on
# time-driven rotation, not on restarts
# or size-driven rotation. Default is
# off, meaning append to existing files
# in all cases.
#log_rotation_age = 1d # Automatic rotation of logfiles will
# happen after that time. 0 disables.
#log_rotation_size = 10MB # Automatic rotation of logfiles will
# happen after that much log output.
# 0 disables.
# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'
#syslog_sequence_numbers = on
#syslog_split_messages = on
# This is only relevant when logging to eventlog (win32):
# (change requires restart)
#event_source = 'PostgreSQL'
# - When to Log -
#client_min_messages = notice # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# log
# notice
# warning
# error
#log_min_messages = warning # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic
#log_min_error_statement = error # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic (effectively off)
#log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements
# and their durations, > 0 logs only
# statements running at least this number
# of milliseconds
# - What to Log -
#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_error_verbosity = default # terse, default, or verbose messages
#log_hostname = off
#log_line_prefix = '%m [%p] ' # special values:
# %a = application name
# %u = user name
# %d = database name
# %r = remote host and port
# %h = remote host
# %p = process ID
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %n = timestamp with milliseconds (as a Unix epoch)
# %i = command tag
# %e = SQL state
# %c = session ID
# %l = session line number
# %s = session start timestamp
# %v = virtual transaction ID
# %x = transaction ID (0 if none)
# %q = stop here in non-session
# processes
# %% = '%'
# e.g. '<%u%%%d> '
#log_lock_waits = off # log lock waits >= deadlock_timeout
#log_statement = 'none' # none, ddl, mod, all
#log_replication_commands = off
#log_temp_files = -1 # log temporary files equal or larger
# than the specified size in kilobytes;
# -1 disables, 0 logs all temp files
log_timezone = 'W-SU'
# - Process Title -
#cluster_name = '' # added to process titles if nonempty
# (change requires restart)
#update_process_title = on
#------------------------------------------------------------------------------
# RUNTIME STATISTICS
#------------------------------------------------------------------------------
# - Query/Index Statistics Collector -
#track_activities = on
#track_counts = on
#track_io_timing = off
#track_functions = none # none, pl, all
#track_activity_query_size = 1024 # (change requires restart)
#stats_temp_directory = 'pg_stat_tmp'
# - Statistics Monitoring -
#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off
#------------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------------------------------------
#autovacuum = on # Enable autovacuum subprocess? 'on'
# requires track_counts to also be on.
#log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and
# their durations, > 0 logs only
# actions running at least this number
# of milliseconds.
#autovacuum_max_workers = 3 # max number of autovacuum subprocesses
# (change requires restart)
#autovacuum_naptime = 1min # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
# vacuum
#autovacuum_analyze_threshold = 50 # min number of row updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_multixact_freeze_max_age = 400000000 # maximum multixact age
# before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for
# autovacuum, in milliseconds;
# -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit
#------------------------------------------------------------------------------
# CLIENT CONNECTION DEFAULTS
#------------------------------------------------------------------------------
# - Statement Behavior -
#search_path = '"$user", public' # schema names
#default_tablespace = '' # a tablespace name, '' uses the default
#temp_tablespaces = '' # a list of tablespace names, '' uses
# only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#default_transaction_deferrable = off
#session_replication_role = 'origin'
#statement_timeout = 0 # in milliseconds, 0 is disabled
#lock_timeout = 0 # in milliseconds, 0 is disabled
#idle_in_transaction_session_timeout = 0 # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#vacuum_multixact_freeze_min_age = 5000000
#vacuum_multixact_freeze_table_age = 150000000
#bytea_output = 'hex' # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'
#gin_fuzzy_search_limit = 0
#gin_pending_list_limit = 4MB
# - Locale and Formatting -
datestyle = 'iso, dmy'
#intervalstyle = 'postgres'
timezone = 'W-SU'
#timezone_abbreviations = 'Default' # Select the set of available time zone
# abbreviations. Currently, there are
# Default
# Australia (historical usage)
# India
# You can create your own file in
# share/timezonesets/.
#extra_float_digits = 0 # min -15, max 3
#client_encoding = sql_ascii # actually, defaults to database
# encoding
# These settings are initialized by initdb, but they can be changed.
lc_messages = 'en_US.UTF-8' # locale for system error message
# strings
lc_monetary = 'ru_RU.UTF-8' # locale for monetary formatting
lc_numeric = 'ru_RU.UTF-8' # locale for number formatting
lc_time = 'ru_RU.UTF-8' # locale for time formatting
# default configuration for text search
default_text_search_config = 'pg_catalog.english'
# - Other Defaults -
#dynamic_library_path = '$libdir'
#local_preload_libraries = ''
#session_preload_libraries = ''
#------------------------------------------------------------------------------
# LOCK MANAGEMENT
#------------------------------------------------------------------------------
#deadlock_timeout = 1s
#max_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_relation = -2 # negative values mean
# (max_pred_locks_per_transaction
# / -max_pred_locks_per_relation) - 1
#max_pred_locks_per_page = 2 # min 0
#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------
# - Previous PostgreSQL Versions -
#array_nulls = on
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = on
#lo_compat_privileges = off
#operator_precedence_warning = off
#quote_all_identifiers = off
#standard_conforming_strings = on
#synchronize_seqscans = on
# - Other Platforms and Clients -
#transform_null_equals = off
#------------------------------------------------------------------------------
# ERROR HANDLING
#------------------------------------------------------------------------------
#exit_on_error = off # terminate session on any error?
#restart_after_crash = on # reinitialize after backend crash?
#------------------------------------------------------------------------------
# CONFIG FILE INCLUDES
#------------------------------------------------------------------------------
# These options allow settings to be loaded from files other than the
# default postgresql.conf.
#include_dir = 'conf.d' # include files ending in '.conf' from
# directory 'conf.d'
#include_if_exists = 'exists.conf' # include file only if it exists
#include = 'special.conf' # include file
#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------
# Add settings for extensions here
Attachments:
[text/x-patch] generic_xlog_diffdelta_v2.patch (21.7K, ../../[email protected]/2-generic_xlog_diffdelta_v2.patch)
download | inline diff:
diff --git a/src/backend/access/transam/generic_xlog.c b/src/backend/access/transam/generic_xlog.c
index 3adbf7b..2ed4146 100644
--- a/src/backend/access/transam/generic_xlog.c
+++ b/src/backend/access/transam/generic_xlog.c
@@ -44,8 +44,16 @@
*-------------------------------------------------------------------------
*/
#define FRAGMENT_HEADER_SIZE (2 * sizeof(OffsetNumber))
+#define DIFF_DELTA_HEADER_SIZE (sizeof(char) + sizeof(int))
#define MATCH_THRESHOLD FRAGMENT_HEADER_SIZE
-#define MAX_DELTA_SIZE (BLCKSZ + 2 * FRAGMENT_HEADER_SIZE)
+#define MAX_DELTA_SIZE (BLCKSZ + 2 * FRAGMENT_HEADER_SIZE + \
+ 2 * DIFF_DELTA_HEADER_SIZE) + sizeof(bool)
+
+#define MAX_ALIGN_MISMATCHES 24
+/* MAX_ALIGN_MISMATCHES is supposed to be not greater than PG_UINT8_MAX */
+
+#define writeToPtr(ptr, x) memcpy(ptr, &(x), sizeof(x)), ptr += sizeof(x)
+#define readFromPtr(ptr, x) memcpy(&(x), ptr, sizeof(x)), ptr += sizeof(x)
/* Struct of generic xlog data for single page */
typedef struct
@@ -71,15 +79,62 @@ struct GenericXLogState
bool isLogged;
};
+/* Describes for the region which type of delta is used in it */
+typedef enum
+{
+ DIFF_DELTA = 0, /* diff delta with insert, remove and replace
+ * operations */
+ BASE_DELTA = 1 /* base delta with update operations only */
+} DeltaType;
+
+/* Diff delta operations for transforming current page to target page */
+typedef enum
+{
+ DIFF_INSERT = 0,
+ DIFF_REMOVE = 1,
+ DIFF_REPLACE = 2
+} DiffDeltaOperations;
+
static void writeFragment(PageData *pageData, OffsetNumber offset,
OffsetNumber len, const char *data);
static void computeRegionDelta(PageData *pageData,
const char *curpage, const char *targetpage,
int targetStart, int targetEnd,
- int validStart, int validEnd);
+ int validStart, int validEnd,
+ bool forceBaseDelta);
static void computeDelta(PageData *pageData, Page curpage, Page targetpage);
static void applyPageRedo(Page page, const char *delta, Size deltaSize);
+static int alignRegions(const char *curRegion, const char *targetRegion,
+ int curRegionLen, int targetRegionLen);
+
+static bool computeRegionDiffDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd);
+static const char *applyPageDiffRedo(Page page, const char *delta, Size deltaSize);
+
+static void computeRegionBaseDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd);
+static const char *applyPageBaseRedo(Page page, const char *delta, Size deltaSize);
+
+static bool pageDataContainsDiffDelta(PageData *pageData);
+static void downgradeDeltaToBaseFormat(PageData *pageData);
+
+/* Arrays for the alignment building and for the resulting alignments */
+static int V[MAX_ALIGN_MISMATCHES + 1][2 * MAX_ALIGN_MISMATCHES + 1];
+static int prevDiag[MAX_ALIGN_MISMATCHES + 1][2 * MAX_ALIGN_MISMATCHES + 1];
+static int alignmentDiag[MAX_ALIGN_MISMATCHES + 1];
+static char curRegionAligned[BLCKSZ + MAX_ALIGN_MISMATCHES];
+static bool curRegionAlignedGap[BLCKSZ + MAX_ALIGN_MISMATCHES];
+static char targetRegionAligned[BLCKSZ + MAX_ALIGN_MISMATCHES];
+static bool targetRegionAlignedGap[BLCKSZ + MAX_ALIGN_MISMATCHES];
+
+/* Array for diff delta application */
+static char localPage[BLCKSZ];
+
/*
* Write next fragment into pageData's delta.
@@ -115,14 +170,76 @@ writeFragment(PageData *pageData, OffsetNumber offset, OffsetNumber length,
* Bytes in curpage outside the range validStart to validEnd-1 should be
* considered invalid, and always overwritten with target data.
*
- * This function is a hot spot, so it's worth being as tense as possible
- * about the data-matching loops.
+ * If forceBaseDelta is true, fucntion just calls computeRegionBaseDelta.
+ * Otherwise this function tries to build diff delta first and, if it fails,
+ * uses the base delta. It also provides the header before the delta in which
+ * the type and the length of the delta are contained.
*/
static void
computeRegionDelta(PageData *pageData,
const char *curpage, const char *targetpage,
int targetStart, int targetEnd,
- int validStart, int validEnd)
+ int validStart, int validEnd,
+ bool forceBaseDelta)
+{
+ int length;
+ char header;
+ int prevDeltaLen;
+ bool diff = false;
+ char *ptr = pageData->delta + pageData->deltaLen;
+
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + sizeof(header) +
+ sizeof(length) <= MAX_DELTA_SIZE);
+
+ pageData->deltaLen += sizeof(header) + sizeof(length);
+ prevDeltaLen = pageData->deltaLen;
+
+ /* Try building diff delta only if necessary */
+ if (!forceBaseDelta)
+ {
+ diff = computeRegionDiffDelta(pageData,
+ curpage, targetpage,
+ targetStart, targetEnd,
+ validStart, validEnd);
+ }
+ /*
+ * If we succeeded to make diff delta, just set the header.
+ * Otherwise, make base delta.
+ */
+ if (diff)
+ {
+ header = DIFF_DELTA;
+ }
+ else
+ {
+ header = BASE_DELTA;
+ computeRegionBaseDelta(pageData,
+ curpage, targetpage,
+ targetStart, targetEnd,
+ validStart, validEnd);
+ }
+ length = pageData->deltaLen - prevDeltaLen;
+
+ writeToPtr(ptr, header);
+ writeToPtr(ptr, length);
+}
+
+/*
+ * Compute the XLOG fragments needed to transform a region of curpage into the
+ * corresponding region of targetpage, and append them to pageData's delta
+ * field. The region to transform runs from targetStart to targetEnd-1.
+ * Bytes in curpage outside the range validStart to validEnd-1 should be
+ * considered invalid, and always overwritten with target data.
+ *
+ * This function is a hot spot, so it's worth being as tense as possible
+ * about the data-matching loops.
+ */
+static void
+computeRegionBaseDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd)
{
int i,
loopEnd,
@@ -222,27 +339,458 @@ computeRegionDelta(PageData *pageData,
}
/*
+ * Align curRegion and targetRegion and return the length of the alignment
+ * or -1 if the alignment with number of mismatching positions less than
+ * or equal to MAX_ALIGN_MISMATCHES does not exist.
+ * The algorithm guarantees to find the alignment with the least possible
+ * number of mismathing positions or return that such least number is greater
+ * than MAX_ALIGN_MISMATCHES.
+ *
+ * For a good introduction to the subject, read about the "Levenshtein
+ * distance" in Wikipedia.
+ *
+ * The basic algorithm is described in:
+ * "An O(ND) Difference Algorithm and its Variations", Eugene W. Myers,
+ * Algorithmica Vol. 1, 1986, pp. 251-266,
+ * <http://dx.doi.org/10.1007/BF01840446>,
+ * PDF: <http://mail.xmailserver.net/diff2.pdf>.
+ * See especially section 3, which describes the variation used below.
+ *
+ * This variation requires O(N + D ^ 2) memory and has time complexity O(ND).
+ * We choose it because it is faster than described in section 4.2 modification
+ * with O(N + D) memory requirement.
+ *
+ * The only modification we made to the original algorithm is the introduction
+ * of REPLACE operations, while in the original algorithm only INSERT and
+ * REMOVE are considered. This introduction doesn't affect time and memory
+ * complexity of the algorithm.
+ *
+ * The alignment is stored in curRegionAligned, targetRegionAligned,
+ * curRegionAlignedGap and targetRegionAlignedGap. The first two arrays
+ * contain the aligned data and the second two contain the map of align gaps
+ * in the first two arrays.
+ */
+static int
+alignRegions(const char *curRegion, const char *targetRegion,
+ int curRegionLen, int targetRegionLen)
+{
+ /* Number of mismatches */
+ int m;
+
+ /* Difference between curRegion and targetRegion prefix lengths */
+ int k;
+
+ /* Curbuf and targetRegion prefix lengths */
+ int i,
+ j;
+ /* Result alignment length */
+ int resLen;
+
+ /* Maximal possible result alignment length */
+ int maxResLen;
+
+ /* The length of the equal block */
+ int curLen;
+
+ /* Number of mismathes in the answer */
+ int numMismatches = -1;
+
+ /*
+ * If lengths differ too much, there is no alignment with a small
+ * number of mismatches.
+ */
+ if (!(-MAX_ALIGN_MISMATCHES < curRegionLen - targetRegionLen &&
+ curRegionLen - targetRegionLen < MAX_ALIGN_MISMATCHES))
+ return -1;
+
+ /*
+ * V is an array to store the values of dynamic programming. The first
+ * dimension corresponds to m, i. e. to the number of performed editing
+ * operations, and the second one is for k + m, where k is the number of
+ * a diagonal.
+ * A diagonal numbered k is such points (i, j) where i - j = k.
+ * Here i means the length of curRegion prefix and j means the length
+ * of targetRegion prefix.
+ * V[m][m + k] is the length of the longest prefix of curRegion i
+ * which can be aligned with the prefix of length j of targetRegion
+ * using m editing operations.
+ * In the loop below we initialize V[0][0] and then compute V[m][m + k]
+ * based on, if defined, V[m - 1][m + k - 1], V[m - 1][m + k], and
+ * V[m - 1][m + k + 1].
+ * V[m][m + k] is undefined if k < -m or k > m.
+ */
+ V[0][0] = 0;
+
+ /* Find the longest path with the given number of mismatches */
+ for (m = 0; m <= MAX_ALIGN_MISMATCHES; ++m)
+ {
+ /*
+ * Find the largest prefix alignment with the given number of
+ * mismatches and the given diagonal, i. e. difference between
+ * curRegion and targetRegion prefix lengths.
+ */
+ for (k = -m; k <= m; ++k)
+ {
+ /* Dynamic programming recurrent step */
+ if (m > 0)
+ {
+ i = -1;
+ if (k != -m && k != m &&
+ V[m - 1][m - 1 + k] + 1 > i)
+ {
+ i = V[m - 1][m - 1 + k] + 1;
+ prevDiag[m][m + k] = k;
+ }
+ if (k != -m && k != -m + 1 &&
+ V[m - 1][m - 1 + k - 1] + 1 > i)
+ {
+ i = V[m - 1][m - 1 + k - 1] + 1;
+ prevDiag[m][m + k] = k - 1;
+ }
+ if (k != m && k != m - 1 &&
+ V[m - 1][m - 1 + k + 1] > i)
+ {
+ i = V[m - 1][m - 1 + k + 1];
+ prevDiag[m][m + k] = k + 1;
+ }
+ }
+ else
+ i = 0;
+ j = i - k;
+
+ /* Boundary checks */
+ Assert(i >= 0);
+ Assert(j >= 0);
+
+ /* Increase the prefixes while the bytes are equal */
+ while (i < curRegionLen && j < targetRegionLen &&
+ curRegion[i] == targetRegion[j])
+ i++, j++;
+
+ /*
+ * Save the largest curRegion prefix that was aligned with given
+ * number of mismatches and difference between curRegion and
+ * targetRegion prefix lengths.
+ */
+ V[m][m + k] = i;
+
+ /* If we find the alignment, save its length and break */
+ if (i == curRegionLen && j == targetRegionLen)
+ {
+ numMismatches = m;
+ break;
+ }
+ }
+ /* Break if we find an alignment */
+ if (numMismatches != -1)
+ break;
+ }
+ /* No alignment was found */
+ if (numMismatches == -1)
+ return -1;
+
+ /*
+ * Restore the path k-s for each iteration of the main loop
+ * for the found alignment.
+ */
+ Assert(m >= 0);
+ while (m != 0)
+ {
+ Assert(-m <= k && k <= m);
+ alignmentDiag[m] = k;
+ k = prevDiag[m][m + k];
+ m--;
+ }
+ Assert(k == 0);
+ alignmentDiag[0] = 0;
+
+ /* Clear RegionAlignedGap arrays */
+ maxResLen = Min(curRegionLen, targetRegionLen) + numMismatches;
+ memset(curRegionAlignedGap, 0, maxResLen);
+ memset(targetRegionAlignedGap, 0, maxResLen);
+
+ /* Process the first equal block */
+ resLen = V[0][0];
+ Assert(resLen <= Min(curRegionLen, targetRegionLen));
+ memcpy(curRegionAligned, curRegion, V[0][0]);
+ memcpy(targetRegionAligned, targetRegion, V[0][0]);
+
+ /* Restore the rest of the alignment */
+ for (m = 1; m <= numMismatches; ++m)
+ {
+ /* Initialize the variables for the block */
+ int dk = alignmentDiag[m] - alignmentDiag[m - 1];
+ int prevDiag = alignmentDiag[m - 1];
+ k = alignmentDiag[m];
+ i = V[m - 1][m - 1 + prevDiag];
+ j = i - prevDiag;
+ /* Check state consistency */
+ Assert(0 <= i && i <= curRegionLen);
+ Assert(0 <= j && j <= targetRegionLen);
+
+ /* Check the block operation correctness */
+ Assert(dk == -1 || i < curRegionLen);
+ Assert(dk == 1 || j < targetRegionLen);
+ Assert(-1 <= dk && dk <= 1);
+ Assert(resLen + 1 <= maxResLen);
+
+ /* Do the alignment operation of the block */
+ if (dk == 1 || dk == 0)
+ curRegionAligned[resLen] = curRegion[i++];
+ else
+ curRegionAlignedGap[resLen] = true;
+ if (dk == 0 || dk == -1)
+ targetRegionAligned[resLen] = targetRegion[j++];
+ else
+ targetRegionAlignedGap[resLen] = true;
+ resLen++;
+
+ /* Compute the size of the equal part of the block */
+ curLen = V[m][m + k] - i;
+
+ /* Check whether the equal part of the block is computed correctly */
+ Assert(curLen >= 0);
+ Assert(resLen + curLen <= maxResLen);
+ Assert(memcmp(&curRegion[i], &targetRegion[j], curLen) == 0);
+
+ /* Copy the equal part of the block */
+ memcpy(&curRegionAligned[resLen], &curRegion[i], curLen);
+ memcpy(&targetRegionAligned[resLen], &targetRegion[j], curLen);
+ resLen += curLen;
+ }
+
+ return resLen;
+}
+
+/*
+ * Try to build a short alignment in order to produce a short diff delta.
+ * If fails, return false, otherwise return true and write the delta to
+ * pageData->delta.
+ */
+static bool
+computeRegionDiffDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd)
+{
+ char *ptr = pageData->delta + pageData->deltaLen;
+ int i,
+ j;
+ char type;
+ char len;
+ OffsetNumber start;
+ OffsetNumber tmp;
+
+ int alignmentLength;
+
+ alignmentLength = alignRegions(&curpage[validStart],
+ &targetpage[targetStart],
+ validEnd - validStart,
+ targetEnd - targetStart);
+
+ /* If no proper alignment was found return false */
+ if (alignmentLength < 0)
+ return false;
+
+ /*
+ * Translate the alignment into the set of instructions for transformation
+ * from curRegion into targetRegion, and write these instructions into
+ * pageData->delta.
+ */
+
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + 4 * sizeof(tmp) <= MAX_DELTA_SIZE);
+
+ /* Write start and end indexes of the buffers */
+ tmp = validStart;
+ writeToPtr(ptr, tmp);
+ tmp = validEnd;
+ writeToPtr(ptr, tmp);
+ tmp = targetStart;
+ writeToPtr(ptr, tmp);
+ tmp = targetEnd;
+ writeToPtr(ptr, tmp);
+
+ /* Transform the alignment into the set of instructions */
+ start = 0;
+ for (i = 0; i < alignmentLength; ++i)
+ {
+ /* Verify the alignment */
+ Assert(!curRegionAlignedGap[i] || !targetRegionAlignedGap[i]);
+
+ /* If the values are equal, write no instructions */
+ if (curRegionAligned[i] == targetRegionAligned[i] &&
+ !curRegionAlignedGap[i] && !targetRegionAlignedGap[i])
+ {
+ start++;
+ continue;
+ }
+
+ if (curRegionAlignedGap[i])
+ type = DIFF_INSERT;
+ else if (targetRegionAlignedGap[i])
+ type = DIFF_REMOVE;
+ else
+ type = DIFF_REPLACE;
+
+ /* Find the end of the block of the same instructions */
+ j = i + 1;
+ while (j < alignmentLength)
+ {
+ bool sameType = false;
+
+ switch (type)
+ {
+ case DIFF_INSERT:
+ sameType = (curRegionAlignedGap[j]);
+ break;
+ case DIFF_REMOVE:
+ sameType = (targetRegionAlignedGap[j]);
+ break;
+ case DIFF_REPLACE:
+ sameType = (!curRegionAlignedGap[j] &&
+ !targetRegionAlignedGap[j] &&
+ curRegionAligned[j] != targetRegionAligned[j]);
+ break;
+ default:
+ elog(ERROR, "unrecognized delta operation type: %d", type);
+ break;
+ }
+ if (sameType)
+ j++;
+ else
+ break;
+ }
+ len = j - i;
+
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + sizeof(type) +
+ sizeof(len) + sizeof(start) <= MAX_DELTA_SIZE);
+ /* Write the header for instruction */
+ writeToPtr(ptr, type);
+ writeToPtr(ptr, len);
+ writeToPtr(ptr, start);
+
+ /* Write instruction data and go to the end of the block */
+ if (type != DIFF_REMOVE)
+ {
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + len <= MAX_DELTA_SIZE);
+ while (i < j)
+ {
+ char c = targetRegionAligned[i++];
+
+ writeToPtr(ptr, c);
+ }
+ }
+ else
+ i = j;
+ i--;
+
+ /* Shift start position which shows where to apply instruction */
+ if (type != DIFF_INSERT)
+ start += len;
+ }
+
+ pageData->deltaLen = ptr - pageData->delta;
+
+ return true;
+}
+
+/*
+ * Return whether pageData->delta contains diff deltas or not.
+ */
+static bool
+pageDataContainsDiffDelta(PageData *pageData)
+{
+ char *ptr = pageData->delta + sizeof(bool);
+ char *end = pageData->delta + pageData->deltaLen;
+ char header;
+ int length;
+
+ while (ptr < end)
+ {
+ readFromPtr(ptr, header);
+ readFromPtr(ptr, length);
+
+ if (header == DIFF_DELTA)
+ return true;
+ ptr += length;
+ }
+ return false;
+}
+
+/*
+ * Downgrade pageData->delta to base delta format.
+ *
+ * Only base diffs are allowed to perform the transformation.
+ */
+static void
+downgradeDeltaToBaseFormat(PageData *pageData)
+{
+ char *ptr = pageData->delta;
+ char *end = pageData->delta + pageData->deltaLen;
+ char *cur;
+ bool containsDiffDelta;
+ char header;
+ int length;
+ int newDeltaLength = 0;
+
+ /* Check whether containsDiffDelta is false */
+ readFromPtr(ptr, containsDiffDelta);
+ Assert(!containsDiffDelta);
+
+ cur = ptr;
+ while (ptr < end)
+ {
+ readFromPtr(ptr, header);
+ readFromPtr(ptr, length);
+
+ /* Check whether the region delta is base delta */
+ Assert(header == BASE_DELTA);
+ newDeltaLength += length;
+
+ memmove(cur, ptr, length);
+ cur += length;
+ ptr += length;
+ }
+ pageData->deltaLen = newDeltaLength;
+}
+
+/*
* Compute the XLOG delta record needed to transform curpage into targetpage,
* and store it in pageData's delta field.
*/
static void
computeDelta(PageData *pageData, Page curpage, Page targetpage)
{
+ bool *containsDiffDelta = pageData->delta;
int targetLower = ((PageHeader) targetpage)->pd_lower,
targetUpper = ((PageHeader) targetpage)->pd_upper,
curLower = ((PageHeader) curpage)->pd_lower,
curUpper = ((PageHeader) curpage)->pd_upper;
- pageData->deltaLen = 0;
+ pageData->deltaLen = sizeof(bool);
/* Compute delta records for lower part of page ... */
computeRegionDelta(pageData, curpage, targetpage,
0, targetLower,
- 0, curLower);
+ 0, curLower,
+ false);
/* ... and for upper part, ignoring what's between */
computeRegionDelta(pageData, curpage, targetpage,
targetUpper, BLCKSZ,
- curUpper, BLCKSZ);
+ curUpper, BLCKSZ,
+ true);
+
+ /*
+ * Set first byte to true if at least one of the region deltas
+ * is diff delta. Otherwise set first byte to false and downgrade all
+ * regions to base format without extra headers.
+ */
+ *containsDiffDelta = pageDataContainsDiffDelta(pageData);
+ if (!(*containsDiffDelta))
+ downgradeDeltaToBaseFormat(pageData);
/*
* If xlog debug is enabled, then check produced delta. Result of delta
@@ -451,12 +999,58 @@ GenericXLogAbort(GenericXLogState *state)
/*
* Apply delta to given page image.
+ *
+ * Read blocks of instructions and apply them based on their type:
+ * BASE_DELTA or DIFF_DELTA.
*/
static void
applyPageRedo(Page page, const char *delta, Size deltaSize)
{
const char *ptr = delta;
const char *end = delta + deltaSize;
+ char header;
+ int length;
+ bool containsDiffDelta;
+
+ /* If page delta is base delta, apply it. */
+ readFromPtr(ptr, containsDiffDelta);
+ if (!containsDiffDelta)
+ {
+ applyPageBaseRedo(page, ptr, end - ptr);
+ return;
+ }
+
+ /* Otherwise apply each region delta. */
+ while (ptr < end)
+ {
+ readFromPtr(ptr, header);
+ readFromPtr(ptr, length);
+
+ switch (header)
+ {
+ case DIFF_DELTA:
+ ptr = applyPageDiffRedo(page, ptr, length);
+ break;
+ case BASE_DELTA:
+ ptr = applyPageBaseRedo(page, ptr, length);
+ break;
+ default:
+ elog(ERROR,
+ "unrecognized delta type: %d",
+ header);
+ break;
+ }
+ }
+}
+
+/*
+ * Apply base delta to given page image.
+ */
+static const char *
+applyPageBaseRedo(Page page, const char *delta, Size deltaSize)
+{
+ const char *ptr = delta;
+ const char *end = delta + deltaSize;
while (ptr < end)
{
@@ -472,6 +1066,80 @@ applyPageRedo(Page page, const char *delta, Size deltaSize)
ptr += length;
}
+ return ptr;
+}
+
+/*
+ * Apply diff delta to given page image.
+ */
+static const char *
+applyPageDiffRedo(Page page, const char *delta, Size deltaSize)
+{
+ const char *ptr = delta;
+ const char *end = delta + deltaSize;
+ OffsetNumber targetStart,
+ targetEnd;
+ OffsetNumber validStart,
+ validEnd;
+ int i,
+ j;
+ OffsetNumber start;
+
+ /* Read start and end indexes of the buffers */
+ readFromPtr(ptr, validStart);
+ readFromPtr(ptr, validEnd);
+ readFromPtr(ptr, targetStart);
+ readFromPtr(ptr, targetEnd);
+
+ /* Read and apply the instructions */
+ i = 0, j = 0;
+ while (ptr < end)
+ {
+ char type;
+ char len;
+
+ /* Read the header of the current instruction */
+ readFromPtr(ptr, type);
+ readFromPtr(ptr, len);
+ readFromPtr(ptr, start);
+
+ /* Copy the data before current instruction to buffer */
+ memcpy(&localPage[j], page + validStart + i, start - i);
+ j += start - i;
+ i = start;
+
+ /* Apply the instruction */
+ switch (type)
+ {
+ case DIFF_INSERT:
+ memcpy(&localPage[j], ptr, len);
+ ptr += len;
+ j += len;
+ break;
+ case DIFF_REMOVE:
+ i += len;
+ break;
+ case DIFF_REPLACE:
+ memcpy(&localPage[j], ptr, len);
+ i += len;
+ j += len;
+ ptr += len;
+ break;
+ default:
+ elog(ERROR,
+ "unrecognized delta instruction type: %d",
+ type);
+ break;
+ }
+ }
+
+ /* Copy the data after the last instruction */
+ memcpy(&localPage[j], page + validStart + i, validEnd - validStart - i);
+ j += validEnd - validStart - i;
+ i = validEnd - validStart;
+
+ memcpy(page + targetStart, localPage, j);
+ return ptr;
}
/*
[text/plain] postgresql.conf (22.2K, ../../[email protected]/3-postgresql.conf)
download | inline:
# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
# name = value
#
# (The "=" is optional.) Whitespace may be used. Comments are introduced with
# "#" anywhere on a line. The complete list of parameter names and allowed
# values can be found in the PostgreSQL documentation.
#
# The commented-out settings shown in this file represent the default values.
# Re-commenting a setting is NOT sufficient to revert it to the default value;
# you need to reload the server.
#
# This file is read on server startup and when the server receives a SIGHUP
# signal. If you edit the file on a running system, you have to SIGHUP the
# server for the changes to take effect, run "pg_ctl reload", or execute
# "SELECT pg_reload_conf()". Some parameters, which are marked below,
# require a server shutdown and restart to take effect.
#
# Any parameter can also be given as a command-line option to the server, e.g.,
# "postgres -c log_connections=on". Some parameters can be changed at run time
# with the "SET" SQL command.
#
# Memory units: kB = kilobytes Time units: ms = milliseconds
# MB = megabytes s = seconds
# GB = gigabytes min = minutes
# TB = terabytes h = hours
# d = days
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable, represented here as ConfigDir.
#data_directory = 'ConfigDir' # use data in another directory
# (change requires restart)
#hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
# (change requires restart)
#ident_file = 'ConfigDir/pg_ident.conf' # ident configuration file
# (change requires restart)
# If external_pid_file is not explicitly set, no extra PID file is written.
#external_pid_file = '' # write an extra PID file
# (change requires restart)
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
#listen_addresses = 'localhost' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost'; use '*' for all
# (change requires restart)
#port = 5845 # (change requires restart)
max_connections = 100 # (change requires restart)
#superuser_reserved_connections = 3 # (change requires restart)
#unix_socket_directories = '/tmp' # comma-separated list of directories
# (change requires restart)
#unix_socket_group = '' # (change requires restart)
#unix_socket_permissions = 0777 # begin with 0 to use octal notation
# (change requires restart)
#bonjour = off # advertise server via Bonjour
# (change requires restart)
#bonjour_name = '' # defaults to the computer name
# (change requires restart)
# - Security and Authentication -
#authentication_timeout = 1min # 1s-600s
#ssl = off
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_dh_params_file = ''
#ssl_cert_file = 'server.crt'
#ssl_key_file = 'server.key'
#ssl_ca_file = ''
#ssl_crl_file = ''
#password_encryption = md5 # md5 or scram-sha-256
#db_user_namespace = off
#row_security = on
# GSSAPI using Kerberos
#krb_server_keyfile = ''
#krb_caseins_users = off
# - TCP Keepalives -
# see "man 7 tcp" for details
#tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds;
# 0 selects the system default
#tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds;
# 0 selects the system default
#tcp_keepalives_count = 0 # TCP_KEEPCNT;
# 0 selects the system default
#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------
# - Memory -
shared_buffers = 1024MB # min 128kB
# (change requires restart)
#huge_pages = try # on, off, or try
# (change requires restart)
#temp_buffers = 8MB # min 800kB
#max_prepared_transactions = 0 # zero disables the feature
# (change requires restart)
# Caution: it is not advisable to set max_prepared_transactions nonzero unless
# you actively intend to use prepared transactions.
#work_mem = 4MB # min 64kB
#maintenance_work_mem = 64MB # min 1MB
#replacement_sort_tuples = 150000 # limits use of replacement selection sort
#autovacuum_work_mem = -1 # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB # min 100kB
dynamic_shared_memory_type = posix # the default is the first option
# supported by the operating system:
# posix
# sysv
# windows
# mmap
# use none to disable dynamic shared memory
# (change requires restart)
# - Disk -
#temp_file_limit = -1 # limits per-process temp file space
# in kB, or -1 for no limit
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
# (change requires restart)
#shared_preload_libraries = '' # (change requires restart)
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0 # 0-100 milliseconds
#vacuum_cost_page_hit = 1 # 0-10000 credits
#vacuum_cost_page_miss = 10 # 0-10000 credits
#vacuum_cost_page_dirty = 20 # 0-10000 credits
#vacuum_cost_limit = 200 # 1-10000 credits
# - Background Writer -
bgwriter_delay = 20ms # 10-10000ms between rounds
bgwriter_lru_maxpages = 800 # 0-1000 max buffers written/round
bgwriter_lru_multiplier = 8.0 # 0-10.0 multiplier on buffers scanned/round
#bgwriter_flush_after = 512kB # measured in pages, 0 disables
# - Asynchronous Behavior -
#effective_io_concurrency = 1 # 1-1000; 0 disables prefetching
#max_worker_processes = 8 # (change requires restart)
#max_parallel_workers_per_gather = 2 # taken from max_parallel_workers
#max_parallel_workers = 8 # maximum number of max_worker_processes that
# can be used in parallel queries
#old_snapshot_threshold = -1 # 1min-60d; -1 disables; 0 is immediate
# (change requires restart)
#backend_flush_after = 0 # measured in pages, 0 disables
#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------
# - Settings -
wal_level = minimal # minimal, replica, or logical
# (change requires restart)
fsync = off # flush data to disk for crash safety
# (turning this off can cause
# unrecoverable data corruption)
synchronous_commit = off # synchronization level;
# off, local, remote_write, remote_apply, or on
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
# fdatasync (default on Linux)
# fsync
# fsync_writethrough
# open_sync
full_page_writes = off # recover from partial page writes
#wal_compression = off # enable compression of full-page writes
#wal_log_hints = off # also do full page writes of non-critical updates
# (change requires restart)
#wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers
# (change requires restart)
#wal_writer_delay = 200ms # 1-10000 milliseconds
#wal_writer_flush_after = 1MB # measured in pages, 0 disables
#commit_delay = 0 # range 0-100000, in microseconds
#commit_siblings = 5 # range 1-1000
# - Checkpoints -
checkpoint_timeout = 120min # range 30s-1d
max_wal_size = 8GB
min_wal_size = 1GB
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_flush_after = 256kB # measured in pages, 0 disables
#checkpoint_warning = 30s # 0 disables
# - Archiving -
#archive_mode = off # enables archiving; off, on, or always
# (change requires restart)
#archive_command = '' # command to use to archive a logfile segment
# placeholders: %p = path of file to archive
# %f = file name only
# e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
#archive_timeout = 0 # force a logfile segment switch after this
# number of seconds; 0 disables
#------------------------------------------------------------------------------
# REPLICATION
#------------------------------------------------------------------------------
# - Sending Server(s) -
# Set these on the master and on any standby that will send replication data.
max_wal_senders = 0 # max number of walsender processes
# (change requires restart)
#wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables
#wal_sender_timeout = 60s # in milliseconds; 0 disables
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
#track_commit_timestamp = off # collect timestamp of transaction commit
# (change requires restart)
# - Master Server -
# These settings are ignored on a standby server.
#synchronous_standby_names = '' # standby servers that provide sync rep
# method to choose sync standbys, number of sync standbys,
# and comma-separated list of application_name
# from standby(s); '*' = all
#vacuum_defer_cleanup_age = 0 # number of xacts by which cleanup is delayed
# - Standby Servers -
# These settings are ignored on a master server.
#hot_standby = on # "off" disallows queries during recovery
# (change requires restart)
#max_standby_archive_delay = 30s # max delay before canceling queries
# when reading WAL from archive;
# -1 allows indefinite delay
#max_standby_streaming_delay = 30s # max delay before canceling queries
# when reading streaming WAL;
# -1 allows indefinite delay
#wal_receiver_status_interval = 10s # send replies at least this often
# 0 disables
#hot_standby_feedback = off # send info from standby to prevent
# query conflicts
#wal_receiver_timeout = 60s # time that receiver waits for
# communication from master
# in milliseconds; 0 disables
#wal_retrieve_retry_interval = 5s # time to wait before retrying to
# retrieve WAL after a failed attempt
# - Subscribers -
# These settings are ignored on a publisher.
#max_logical_replication_workers = 4 # taken from max_worker_processes
# (change requires restart)
#max_sync_workers_per_subscription = 2 # taken from max_logical_replication_workers
#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on
# - Planner Cost Constants -
#seq_page_cost = 1.0 # measured on an arbitrary scale
#random_page_cost = 4.0 # same scale as above
#cpu_tuple_cost = 0.01 # same scale as above
#cpu_index_tuple_cost = 0.005 # same scale as above
#cpu_operator_cost = 0.0025 # same scale as above
#parallel_tuple_cost = 0.1 # same scale as above
#parallel_setup_cost = 1000.0 # same scale as above
#min_parallel_table_scan_size = 8MB
#min_parallel_index_scan_size = 512kB
#effective_cache_size = 4GB
# - Genetic Query Optimizer -
#geqo = on
#geqo_threshold = 12
#geqo_effort = 5 # range 1-10
#geqo_pool_size = 0 # selects default based on effort
#geqo_generations = 0 # selects default based on effort
#geqo_selection_bias = 2.0 # range 1.5-2.0
#geqo_seed = 0.0 # range 0.0-1.0
# - Other Planner Options -
#default_statistics_target = 100 # range 1-10000
#constraint_exclusion = partition # on, off, or partition
#cursor_tuple_fraction = 0.1 # range 0.0-1.0
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
# JOIN clauses
#force_parallel_mode = off
#------------------------------------------------------------------------------
# ERROR REPORTING AND LOGGING
#------------------------------------------------------------------------------
# - Where to Log -
#log_destination = 'stderr' # Valid values are combinations of
# stderr, csvlog, syslog, and eventlog,
# depending on platform. csvlog
# requires logging_collector to be on.
# This is used when logging to stderr:
#logging_collector = off # Enable capturing of stderr and csvlog
# into log files. Required to be on for
# csvlogs.
# (change requires restart)
# These are only used if logging_collector is on:
#log_directory = 'log' # directory where log files are written,
# can be absolute or relative to PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern,
# can include strftime() escapes
#log_file_mode = 0600 # creation mode for log files,
# begin with 0 to use octal notation
#log_truncate_on_rotation = off # If on, an existing log file with the
# same name as the new log file will be
# truncated rather than appended to.
# But such truncation only occurs on
# time-driven rotation, not on restarts
# or size-driven rotation. Default is
# off, meaning append to existing files
# in all cases.
#log_rotation_age = 1d # Automatic rotation of logfiles will
# happen after that time. 0 disables.
#log_rotation_size = 10MB # Automatic rotation of logfiles will
# happen after that much log output.
# 0 disables.
# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'
#syslog_sequence_numbers = on
#syslog_split_messages = on
# This is only relevant when logging to eventlog (win32):
# (change requires restart)
#event_source = 'PostgreSQL'
# - When to Log -
#client_min_messages = notice # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# log
# notice
# warning
# error
#log_min_messages = warning # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic
#log_min_error_statement = error # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic (effectively off)
#log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements
# and their durations, > 0 logs only
# statements running at least this number
# of milliseconds
# - What to Log -
#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_error_verbosity = default # terse, default, or verbose messages
#log_hostname = off
#log_line_prefix = '%m [%p] ' # special values:
# %a = application name
# %u = user name
# %d = database name
# %r = remote host and port
# %h = remote host
# %p = process ID
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %n = timestamp with milliseconds (as a Unix epoch)
# %i = command tag
# %e = SQL state
# %c = session ID
# %l = session line number
# %s = session start timestamp
# %v = virtual transaction ID
# %x = transaction ID (0 if none)
# %q = stop here in non-session
# processes
# %% = '%'
# e.g. '<%u%%%d> '
#log_lock_waits = off # log lock waits >= deadlock_timeout
#log_statement = 'none' # none, ddl, mod, all
#log_replication_commands = off
#log_temp_files = -1 # log temporary files equal or larger
# than the specified size in kilobytes;
# -1 disables, 0 logs all temp files
log_timezone = 'W-SU'
# - Process Title -
#cluster_name = '' # added to process titles if nonempty
# (change requires restart)
#update_process_title = on
#------------------------------------------------------------------------------
# RUNTIME STATISTICS
#------------------------------------------------------------------------------
# - Query/Index Statistics Collector -
#track_activities = on
#track_counts = on
#track_io_timing = off
#track_functions = none # none, pl, all
#track_activity_query_size = 1024 # (change requires restart)
#stats_temp_directory = 'pg_stat_tmp'
# - Statistics Monitoring -
#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off
#------------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------------------------------------
#autovacuum = on # Enable autovacuum subprocess? 'on'
# requires track_counts to also be on.
#log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and
# their durations, > 0 logs only
# actions running at least this number
# of milliseconds.
#autovacuum_max_workers = 3 # max number of autovacuum subprocesses
# (change requires restart)
#autovacuum_naptime = 1min # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
# vacuum
#autovacuum_analyze_threshold = 50 # min number of row updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_multixact_freeze_max_age = 400000000 # maximum multixact age
# before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for
# autovacuum, in milliseconds;
# -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit
#------------------------------------------------------------------------------
# CLIENT CONNECTION DEFAULTS
#------------------------------------------------------------------------------
# - Statement Behavior -
#search_path = '"$user", public' # schema names
#default_tablespace = '' # a tablespace name, '' uses the default
#temp_tablespaces = '' # a list of tablespace names, '' uses
# only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#default_transaction_deferrable = off
#session_replication_role = 'origin'
#statement_timeout = 0 # in milliseconds, 0 is disabled
#lock_timeout = 0 # in milliseconds, 0 is disabled
#idle_in_transaction_session_timeout = 0 # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#vacuum_multixact_freeze_min_age = 5000000
#vacuum_multixact_freeze_table_age = 150000000
#bytea_output = 'hex' # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'
#gin_fuzzy_search_limit = 0
#gin_pending_list_limit = 4MB
# - Locale and Formatting -
datestyle = 'iso, dmy'
#intervalstyle = 'postgres'
timezone = 'W-SU'
#timezone_abbreviations = 'Default' # Select the set of available time zone
# abbreviations. Currently, there are
# Default
# Australia (historical usage)
# India
# You can create your own file in
# share/timezonesets/.
#extra_float_digits = 0 # min -15, max 3
#client_encoding = sql_ascii # actually, defaults to database
# encoding
# These settings are initialized by initdb, but they can be changed.
lc_messages = 'en_US.UTF-8' # locale for system error message
# strings
lc_monetary = 'ru_RU.UTF-8' # locale for monetary formatting
lc_numeric = 'ru_RU.UTF-8' # locale for number formatting
lc_time = 'ru_RU.UTF-8' # locale for time formatting
# default configuration for text search
default_text_search_config = 'pg_catalog.english'
# - Other Defaults -
#dynamic_library_path = '$libdir'
#local_preload_libraries = ''
#session_preload_libraries = ''
#------------------------------------------------------------------------------
# LOCK MANAGEMENT
#------------------------------------------------------------------------------
#deadlock_timeout = 1s
#max_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_relation = -2 # negative values mean
# (max_pred_locks_per_transaction
# / -max_pred_locks_per_relation) - 1
#max_pred_locks_per_page = 2 # min 0
#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------
# - Previous PostgreSQL Versions -
#array_nulls = on
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = on
#lo_compat_privileges = off
#operator_precedence_warning = off
#quote_all_identifiers = off
#standard_conforming_strings = on
#synchronize_seqscans = on
# - Other Platforms and Clients -
#transform_null_equals = off
#------------------------------------------------------------------------------
# ERROR HANDLING
#------------------------------------------------------------------------------
#exit_on_error = off # terminate session on any error?
#restart_after_crash = on # reinitialize after backend crash?
#------------------------------------------------------------------------------
# CONFIG FILE INCLUDES
#------------------------------------------------------------------------------
# These options allow settings to be loaded from files other than the
# default postgresql.conf.
#include_dir = 'conf.d' # include files ending in '.conf' from
# directory 'conf.d'
#include_if_exists = 'exists.conf' # include file only if it exists
#include = 'special.conf' # include file
#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------
# Add settings for extensions here
[application/sql] test00.sql (1.7K, ../../[email protected]/4-test00.sql)
download
[application/sql] test01.sql (1.7K, ../../[email protected]/5-test01.sql)
download
[application/x-shellscript] test_correctness.sh (1.6K, ../../[email protected]/6-test_correctness.sh)
download
[application/x-shellscript] total_test.sh (4.9K, ../../[email protected]/7-total_test.sh)
download
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: [HACKERS] Proposal: generic WAL compression
@ 2018-03-13 14:36 Oleg Ivanov <[email protected]>
parent: Markus Nullmeier <[email protected]>
1 sibling, 0 replies; 14+ messages in thread
From: Oleg Ivanov @ 2018-03-13 14:36 UTC (permalink / raw)
To: Markus Nullmeier <[email protected]>; David Steele <[email protected]>; pgsql-hackers; +Cc: Stephen Frost <[email protected]>; Antonin Houska <[email protected]>
On 02/07/2018 09:02 PM, Markus Nullmeier wrote:
> One general comment I can already make is that enabling compression
> should be made optional, which appears to be a small and easy addition
> to the generic WAL API.
The new version of the patch is attached.
In order to control generic WAL compression the new structure
PageXLogCompressParams is introduced. It is passed as an additional
parameter into GenericXLogRegisterBufferEx, so the access method
can control its own WAL compression.
GenericXLogRegisterBuffer uses default compression settings which
appeared to be a reasonable tradeoff between performance overheads
and compression rate on RUM. On my HDD PostgreSQL works even 10%
faster for some RUM workloads because of reducing size of generic
WAL to be written.
Oleg Ivanov
Postgres Professional
The Russian PostgreSQL Company
# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
# name = value
#
# (The "=" is optional.) Whitespace may be used. Comments are introduced with
# "#" anywhere on a line. The complete list of parameter names and allowed
# values can be found in the PostgreSQL documentation.
#
# The commented-out settings shown in this file represent the default values.
# Re-commenting a setting is NOT sufficient to revert it to the default value;
# you need to reload the server.
#
# This file is read on server startup and when the server receives a SIGHUP
# signal. If you edit the file on a running system, you have to SIGHUP the
# server for the changes to take effect, run "pg_ctl reload", or execute
# "SELECT pg_reload_conf()". Some parameters, which are marked below,
# require a server shutdown and restart to take effect.
#
# Any parameter can also be given as a command-line option to the server, e.g.,
# "postgres -c log_connections=on". Some parameters can be changed at run time
# with the "SET" SQL command.
#
# Memory units: kB = kilobytes Time units: ms = milliseconds
# MB = megabytes s = seconds
# GB = gigabytes min = minutes
# TB = terabytes h = hours
# d = days
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable, represented here as ConfigDir.
#data_directory = 'ConfigDir' # use data in another directory
# (change requires restart)
#hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
# (change requires restart)
#ident_file = 'ConfigDir/pg_ident.conf' # ident configuration file
# (change requires restart)
# If external_pid_file is not explicitly set, no extra PID file is written.
#external_pid_file = '' # write an extra PID file
# (change requires restart)
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
#listen_addresses = 'localhost' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost'; use '*' for all
# (change requires restart)
#port = 5845 # (change requires restart)
max_connections = 100 # (change requires restart)
#superuser_reserved_connections = 3 # (change requires restart)
#unix_socket_directories = '/tmp' # comma-separated list of directories
# (change requires restart)
#unix_socket_group = '' # (change requires restart)
#unix_socket_permissions = 0777 # begin with 0 to use octal notation
# (change requires restart)
#bonjour = off # advertise server via Bonjour
# (change requires restart)
#bonjour_name = '' # defaults to the computer name
# (change requires restart)
# - Security and Authentication -
#authentication_timeout = 1min # 1s-600s
#ssl = off
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_dh_params_file = ''
#ssl_cert_file = 'server.crt'
#ssl_key_file = 'server.key'
#ssl_ca_file = ''
#ssl_crl_file = ''
#password_encryption = md5 # md5 or scram-sha-256
#db_user_namespace = off
#row_security = on
# GSSAPI using Kerberos
#krb_server_keyfile = ''
#krb_caseins_users = off
# - TCP Keepalives -
# see "man 7 tcp" for details
#tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds;
# 0 selects the system default
#tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds;
# 0 selects the system default
#tcp_keepalives_count = 0 # TCP_KEEPCNT;
# 0 selects the system default
#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------
# - Memory -
shared_buffers = 1024MB # min 128kB
# (change requires restart)
#huge_pages = try # on, off, or try
# (change requires restart)
#temp_buffers = 8MB # min 800kB
#max_prepared_transactions = 0 # zero disables the feature
# (change requires restart)
# Caution: it is not advisable to set max_prepared_transactions nonzero unless
# you actively intend to use prepared transactions.
#work_mem = 4MB # min 64kB
#maintenance_work_mem = 64MB # min 1MB
#replacement_sort_tuples = 150000 # limits use of replacement selection sort
#autovacuum_work_mem = -1 # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB # min 100kB
dynamic_shared_memory_type = posix # the default is the first option
# supported by the operating system:
# posix
# sysv
# windows
# mmap
# use none to disable dynamic shared memory
# (change requires restart)
# - Disk -
#temp_file_limit = -1 # limits per-process temp file space
# in kB, or -1 for no limit
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
# (change requires restart)
#shared_preload_libraries = '' # (change requires restart)
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0 # 0-100 milliseconds
#vacuum_cost_page_hit = 1 # 0-10000 credits
#vacuum_cost_page_miss = 10 # 0-10000 credits
#vacuum_cost_page_dirty = 20 # 0-10000 credits
#vacuum_cost_limit = 200 # 1-10000 credits
# - Background Writer -
bgwriter_delay = 20ms # 10-10000ms between rounds
bgwriter_lru_maxpages = 800 # 0-1000 max buffers written/round
bgwriter_lru_multiplier = 8.0 # 0-10.0 multiplier on buffers scanned/round
#bgwriter_flush_after = 512kB # measured in pages, 0 disables
# - Asynchronous Behavior -
#effective_io_concurrency = 1 # 1-1000; 0 disables prefetching
#max_worker_processes = 8 # (change requires restart)
#max_parallel_workers_per_gather = 2 # taken from max_parallel_workers
#max_parallel_workers = 8 # maximum number of max_worker_processes that
# can be used in parallel queries
#old_snapshot_threshold = -1 # 1min-60d; -1 disables; 0 is immediate
# (change requires restart)
#backend_flush_after = 0 # measured in pages, 0 disables
#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------
# - Settings -
wal_level = minimal # minimal, replica, or logical
# (change requires restart)
fsync = off # flush data to disk for crash safety
# (turning this off can cause
# unrecoverable data corruption)
synchronous_commit = off # synchronization level;
# off, local, remote_write, remote_apply, or on
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
# fdatasync (default on Linux)
# fsync
# fsync_writethrough
# open_sync
full_page_writes = off # recover from partial page writes
#wal_compression = off # enable compression of full-page writes
#wal_log_hints = off # also do full page writes of non-critical updates
# (change requires restart)
#wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers
# (change requires restart)
#wal_writer_delay = 200ms # 1-10000 milliseconds
#wal_writer_flush_after = 1MB # measured in pages, 0 disables
#commit_delay = 0 # range 0-100000, in microseconds
#commit_siblings = 5 # range 1-1000
# - Checkpoints -
checkpoint_timeout = 120min # range 30s-1d
max_wal_size = 8GB
min_wal_size = 1GB
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_flush_after = 256kB # measured in pages, 0 disables
#checkpoint_warning = 30s # 0 disables
# - Archiving -
#archive_mode = off # enables archiving; off, on, or always
# (change requires restart)
#archive_command = '' # command to use to archive a logfile segment
# placeholders: %p = path of file to archive
# %f = file name only
# e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
#archive_timeout = 0 # force a logfile segment switch after this
# number of seconds; 0 disables
#------------------------------------------------------------------------------
# REPLICATION
#------------------------------------------------------------------------------
# - Sending Server(s) -
# Set these on the master and on any standby that will send replication data.
max_wal_senders = 0 # max number of walsender processes
# (change requires restart)
#wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables
#wal_sender_timeout = 60s # in milliseconds; 0 disables
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
#track_commit_timestamp = off # collect timestamp of transaction commit
# (change requires restart)
# - Master Server -
# These settings are ignored on a standby server.
#synchronous_standby_names = '' # standby servers that provide sync rep
# method to choose sync standbys, number of sync standbys,
# and comma-separated list of application_name
# from standby(s); '*' = all
#vacuum_defer_cleanup_age = 0 # number of xacts by which cleanup is delayed
# - Standby Servers -
# These settings are ignored on a master server.
#hot_standby = on # "off" disallows queries during recovery
# (change requires restart)
#max_standby_archive_delay = 30s # max delay before canceling queries
# when reading WAL from archive;
# -1 allows indefinite delay
#max_standby_streaming_delay = 30s # max delay before canceling queries
# when reading streaming WAL;
# -1 allows indefinite delay
#wal_receiver_status_interval = 10s # send replies at least this often
# 0 disables
#hot_standby_feedback = off # send info from standby to prevent
# query conflicts
#wal_receiver_timeout = 60s # time that receiver waits for
# communication from master
# in milliseconds; 0 disables
#wal_retrieve_retry_interval = 5s # time to wait before retrying to
# retrieve WAL after a failed attempt
# - Subscribers -
# These settings are ignored on a publisher.
#max_logical_replication_workers = 4 # taken from max_worker_processes
# (change requires restart)
#max_sync_workers_per_subscription = 2 # taken from max_logical_replication_workers
#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on
# - Planner Cost Constants -
#seq_page_cost = 1.0 # measured on an arbitrary scale
#random_page_cost = 4.0 # same scale as above
#cpu_tuple_cost = 0.01 # same scale as above
#cpu_index_tuple_cost = 0.005 # same scale as above
#cpu_operator_cost = 0.0025 # same scale as above
#parallel_tuple_cost = 0.1 # same scale as above
#parallel_setup_cost = 1000.0 # same scale as above
#min_parallel_table_scan_size = 8MB
#min_parallel_index_scan_size = 512kB
#effective_cache_size = 4GB
# - Genetic Query Optimizer -
#geqo = on
#geqo_threshold = 12
#geqo_effort = 5 # range 1-10
#geqo_pool_size = 0 # selects default based on effort
#geqo_generations = 0 # selects default based on effort
#geqo_selection_bias = 2.0 # range 1.5-2.0
#geqo_seed = 0.0 # range 0.0-1.0
# - Other Planner Options -
#default_statistics_target = 100 # range 1-10000
#constraint_exclusion = partition # on, off, or partition
#cursor_tuple_fraction = 0.1 # range 0.0-1.0
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
# JOIN clauses
#force_parallel_mode = off
#------------------------------------------------------------------------------
# ERROR REPORTING AND LOGGING
#------------------------------------------------------------------------------
# - Where to Log -
#log_destination = 'stderr' # Valid values are combinations of
# stderr, csvlog, syslog, and eventlog,
# depending on platform. csvlog
# requires logging_collector to be on.
# This is used when logging to stderr:
#logging_collector = off # Enable capturing of stderr and csvlog
# into log files. Required to be on for
# csvlogs.
# (change requires restart)
# These are only used if logging_collector is on:
#log_directory = 'log' # directory where log files are written,
# can be absolute or relative to PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern,
# can include strftime() escapes
#log_file_mode = 0600 # creation mode for log files,
# begin with 0 to use octal notation
#log_truncate_on_rotation = off # If on, an existing log file with the
# same name as the new log file will be
# truncated rather than appended to.
# But such truncation only occurs on
# time-driven rotation, not on restarts
# or size-driven rotation. Default is
# off, meaning append to existing files
# in all cases.
#log_rotation_age = 1d # Automatic rotation of logfiles will
# happen after that time. 0 disables.
#log_rotation_size = 10MB # Automatic rotation of logfiles will
# happen after that much log output.
# 0 disables.
# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'
#syslog_sequence_numbers = on
#syslog_split_messages = on
# This is only relevant when logging to eventlog (win32):
# (change requires restart)
#event_source = 'PostgreSQL'
# - When to Log -
#client_min_messages = notice # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# log
# notice
# warning
# error
#log_min_messages = warning # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic
#log_min_error_statement = error # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic (effectively off)
#log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements
# and their durations, > 0 logs only
# statements running at least this number
# of milliseconds
# - What to Log -
#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_error_verbosity = default # terse, default, or verbose messages
#log_hostname = off
#log_line_prefix = '%m [%p] ' # special values:
# %a = application name
# %u = user name
# %d = database name
# %r = remote host and port
# %h = remote host
# %p = process ID
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %n = timestamp with milliseconds (as a Unix epoch)
# %i = command tag
# %e = SQL state
# %c = session ID
# %l = session line number
# %s = session start timestamp
# %v = virtual transaction ID
# %x = transaction ID (0 if none)
# %q = stop here in non-session
# processes
# %% = '%'
# e.g. '<%u%%%d> '
#log_lock_waits = off # log lock waits >= deadlock_timeout
#log_statement = 'none' # none, ddl, mod, all
#log_replication_commands = off
#log_temp_files = -1 # log temporary files equal or larger
# than the specified size in kilobytes;
# -1 disables, 0 logs all temp files
log_timezone = 'W-SU'
# - Process Title -
#cluster_name = '' # added to process titles if nonempty
# (change requires restart)
#update_process_title = on
#------------------------------------------------------------------------------
# RUNTIME STATISTICS
#------------------------------------------------------------------------------
# - Query/Index Statistics Collector -
#track_activities = on
#track_counts = on
#track_io_timing = off
#track_functions = none # none, pl, all
#track_activity_query_size = 1024 # (change requires restart)
#stats_temp_directory = 'pg_stat_tmp'
# - Statistics Monitoring -
#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off
#------------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------------------------------------
#autovacuum = on # Enable autovacuum subprocess? 'on'
# requires track_counts to also be on.
#log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and
# their durations, > 0 logs only
# actions running at least this number
# of milliseconds.
#autovacuum_max_workers = 3 # max number of autovacuum subprocesses
# (change requires restart)
#autovacuum_naptime = 1min # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
# vacuum
#autovacuum_analyze_threshold = 50 # min number of row updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_multixact_freeze_max_age = 400000000 # maximum multixact age
# before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for
# autovacuum, in milliseconds;
# -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit
#------------------------------------------------------------------------------
# CLIENT CONNECTION DEFAULTS
#------------------------------------------------------------------------------
# - Statement Behavior -
#search_path = '"$user", public' # schema names
#default_tablespace = '' # a tablespace name, '' uses the default
#temp_tablespaces = '' # a list of tablespace names, '' uses
# only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#default_transaction_deferrable = off
#session_replication_role = 'origin'
#statement_timeout = 0 # in milliseconds, 0 is disabled
#lock_timeout = 0 # in milliseconds, 0 is disabled
#idle_in_transaction_session_timeout = 0 # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#vacuum_multixact_freeze_min_age = 5000000
#vacuum_multixact_freeze_table_age = 150000000
#bytea_output = 'hex' # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'
#gin_fuzzy_search_limit = 0
#gin_pending_list_limit = 4MB
# - Locale and Formatting -
datestyle = 'iso, dmy'
#intervalstyle = 'postgres'
timezone = 'W-SU'
#timezone_abbreviations = 'Default' # Select the set of available time zone
# abbreviations. Currently, there are
# Default
# Australia (historical usage)
# India
# You can create your own file in
# share/timezonesets/.
#extra_float_digits = 0 # min -15, max 3
#client_encoding = sql_ascii # actually, defaults to database
# encoding
# These settings are initialized by initdb, but they can be changed.
lc_messages = 'en_US.UTF-8' # locale for system error message
# strings
lc_monetary = 'en_US.UTF-8' # locale for monetary formatting
lc_numeric = 'en_US.UTF-8' # locale for number formatting
lc_time = 'en_US.UTF-8' # locale for time formatting
# default configuration for text search
default_text_search_config = 'pg_catalog.english'
# - Other Defaults -
#dynamic_library_path = '$libdir'
#local_preload_libraries = ''
#session_preload_libraries = ''
#------------------------------------------------------------------------------
# LOCK MANAGEMENT
#------------------------------------------------------------------------------
#deadlock_timeout = 1s
#max_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_relation = -2 # negative values mean
# (max_pred_locks_per_transaction
# / -max_pred_locks_per_relation) - 1
#max_pred_locks_per_page = 2 # min 0
#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------
# - Previous PostgreSQL Versions -
#array_nulls = on
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = on
#lo_compat_privileges = off
#operator_precedence_warning = off
#quote_all_identifiers = off
#standard_conforming_strings = on
#synchronize_seqscans = on
# - Other Platforms and Clients -
#transform_null_equals = off
#------------------------------------------------------------------------------
# ERROR HANDLING
#------------------------------------------------------------------------------
#exit_on_error = off # terminate session on any error?
#restart_after_crash = on # reinitialize after backend crash?
#------------------------------------------------------------------------------
# CONFIG FILE INCLUDES
#------------------------------------------------------------------------------
# These options allow settings to be loaded from files other than the
# default postgresql.conf.
#include_dir = 'conf.d' # include files ending in '.conf' from
# directory 'conf.d'
#include_if_exists = 'exists.conf' # include file only if it exists
#include = 'special.conf' # include file
#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------
# Add settings for extensions here
Attachments:
[text/x-patch] generic_xlog_diffdelta_v3.patch (27.9K, ../../[email protected]/2-generic_xlog_diffdelta_v3.patch)
download | inline diff:
diff --git a/src/backend/access/transam/generic_xlog.c b/src/backend/access/transam/generic_xlog.c
index ce02354..fa3cd4e 100644
--- a/src/backend/access/transam/generic_xlog.c
+++ b/src/backend/access/transam/generic_xlog.c
@@ -43,19 +43,41 @@
* a full page's worth of data.
*-------------------------------------------------------------------------
*/
+
+#define MAX_ALIGN_MISMATCHES 255
+/* MAX_ALIGN_MISMATCHES is not supposed to be greater than PG_UINT8_MAX */
+#if MAX_ALIGN_MISMATCHES > PG_UINT8_MAX
+#error "MAX_ALIGN_MISMATCHES must be not greater than PG_UINT8_MAX"
+#endif
+
#define FRAGMENT_HEADER_SIZE (2 * sizeof(OffsetNumber))
+#define REGION_HEADER_SIZE (sizeof(char) + sizeof(int))
+#define DIFF_DELTA_HEADER_SIZE (sizeof(char) + 2 * sizeof(OffsetNumber))
+#define MISMATCH_HEADER_SIZE (sizeof(char) + sizeof(uint8) + \
+ sizeof(OffsetNumber))
#define MATCH_THRESHOLD FRAGMENT_HEADER_SIZE
-#define MAX_DELTA_SIZE (BLCKSZ + 2 * FRAGMENT_HEADER_SIZE)
+#define MAX_DELTA_SIZE (BLCKSZ + \
+ 2 * REGION_HEADER_SIZE + \
+ 2 * FRAGMENT_HEADER_SIZE + \
+ 2 * DIFF_DELTA_HEADER_SIZE + \
+ MAX_ALIGN_MISMATCHES * MISMATCH_HEADER_SIZE \
+ + sizeof(bool))
+
+#define writeToPtr(ptr, x) memcpy(ptr, &(x), sizeof(x)), ptr += sizeof(x)
+#define readFromPtr(ptr, x) memcpy(&(x), ptr, sizeof(x)), ptr += sizeof(x)
/* Struct of generic xlog data for single page */
typedef struct
{
Buffer buffer; /* registered buffer */
int flags; /* flags for this buffer */
+
int deltaLen; /* space consumed in delta field */
char *image; /* copy of page image for modification, do not
* do it in-place to have aligned memory chunk */
char delta[MAX_DELTA_SIZE]; /* delta between page images */
+
+ PageXLogCompressParams compressParams; /* compress parameters */
} PageData;
/* State of generic xlog record construction */
@@ -71,15 +93,77 @@ struct GenericXLogState
bool isLogged;
};
+/* Describes for the region which type of delta is used in it */
+typedef enum
+{
+ DIFF_DELTA = 0, /* diff delta with insert, remove and replace
+ * operations */
+ BASE_DELTA = 1 /* base delta with update operations only */
+} DeltaType;
+
+/* Diff delta operations for transforming current page to target page */
+typedef enum
+{
+ DIFF_INSERT = 0,
+ DIFF_REMOVE = 1,
+ DIFF_REPLACE = 2
+} DiffDeltaOperations;
+
+/* Describes the kind of region of the page */
+typedef enum
+{
+ UPPER_REGION = 0,
+ LOWER_REGION = 1
+} RegionType;
+
static void writeFragment(PageData *pageData, OffsetNumber offset,
OffsetNumber len, const char *data);
static void computeRegionDelta(PageData *pageData,
const char *curpage, const char *targetpage,
int targetStart, int targetEnd,
- int validStart, int validEnd);
+ int validStart, int validEnd,
+ uint8 maxMismatches);
static void computeDelta(PageData *pageData, Page curpage, Page targetpage);
static void applyPageRedo(Page page, const char *delta, Size deltaSize);
+static int alignRegions(const char *curRegion, const char *targetRegion,
+ int curRegionLen, int targetRegionLen, uint8 maxMismatches);
+static int restoreCompactAlignment(const char *curRegion,
+ const char *targetRegion,
+ int curRegionLen,
+ int targetRegionLen,
+ int numMismatches);
+
+static bool computeRegionDiffDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd,
+ uint8 maxMismatches);
+static const char *applyPageDiffRedo(Page page, const char *delta, Size deltaSize);
+
+static void computeRegionBaseDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd);
+static const char *applyPageBaseRedo(Page page, const char *delta, Size deltaSize);
+
+static bool pageDataContainsDiffDelta(PageData *pageData);
+static void downgradeDeltaToBaseFormat(PageData *pageData);
+
+/* Arrays for the alignment building and for the resulting alignments */
+static int V[MAX_ALIGN_MISMATCHES + 1][2 * MAX_ALIGN_MISMATCHES + 1];
+static int prevDiag[MAX_ALIGN_MISMATCHES + 1][2 * MAX_ALIGN_MISMATCHES + 1];
+static int alignmentDiag[MAX_ALIGN_MISMATCHES + 1];
+static char curRegionAligned[MAX_ALIGN_MISMATCHES];
+static bool curRegionAlignedGap[MAX_ALIGN_MISMATCHES];
+static char targetRegionAligned[MAX_ALIGN_MISMATCHES];
+static bool targetRegionAlignedGap[MAX_ALIGN_MISMATCHES];
+static int curRegionAlignedPos[MAX_ALIGN_MISMATCHES];
+static int targetRegionAlignedPos[MAX_ALIGN_MISMATCHES];
+
+/* Array for diff delta application */
+static char localPage[BLCKSZ];
+
/*
* Write next fragment into pageData's delta.
@@ -115,14 +199,82 @@ writeFragment(PageData *pageData, OffsetNumber offset, OffsetNumber length,
* Bytes in curpage outside the range validStart to validEnd-1 should be
* considered invalid, and always overwritten with target data.
*
- * This function is a hot spot, so it's worth being as tense as possible
- * about the data-matching loops.
+ * If forceBaseDelta is true, fucntion just calls computeRegionBaseDelta.
+ * Otherwise this function tries to build diff delta first and, if it fails,
+ * uses the base delta. It also provides the header before the delta in which
+ * the type and the length of the delta are contained.
*/
static void
computeRegionDelta(PageData *pageData,
const char *curpage, const char *targetpage,
int targetStart, int targetEnd,
- int validStart, int validEnd)
+ int validStart, int validEnd,
+ uint8 maxMismatches)
+{
+ int length;
+ char header;
+ int prevDeltaLen;
+ bool diff = false;
+ char *ptr = pageData->delta + pageData->deltaLen;
+
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + sizeof(header) +
+ sizeof(length) <= MAX_DELTA_SIZE);
+
+ pageData->deltaLen += sizeof(header) + sizeof(length);
+ prevDeltaLen = pageData->deltaLen;
+
+ /* Not sure what to do with too big maxMismathes. Now we just clip it. */
+ if (maxMismatches > MAX_ALIGN_MISMATCHES)
+ maxMismatches = MAX_ALIGN_MISMATCHES;
+
+ /* Try building diff delta only if necessary */
+ if (maxMismatches > 0)
+ {
+ diff = computeRegionDiffDelta(pageData,
+ curpage, targetpage,
+ targetStart, targetEnd,
+ validStart, validEnd,
+ maxMismatches);
+ }
+
+ /*
+ * If we succeeded to make diff delta, just set the header. Otherwise,
+ * make base delta.
+ */
+ if (diff)
+ {
+ header = DIFF_DELTA;
+ }
+ else
+ {
+ header = BASE_DELTA;
+ computeRegionBaseDelta(pageData,
+ curpage, targetpage,
+ targetStart, targetEnd,
+ validStart, validEnd);
+ }
+ length = pageData->deltaLen - prevDeltaLen;
+
+ writeToPtr(ptr, header);
+ writeToPtr(ptr, length);
+}
+
+/*
+ * Compute the XLOG fragments needed to transform a region of curpage into the
+ * corresponding region of targetpage, and append them to pageData's delta
+ * field. The region to transform runs from targetStart to targetEnd-1.
+ * Bytes in curpage outside the range validStart to validEnd-1 should be
+ * considered invalid, and always overwritten with target data.
+ *
+ * This function is a hot spot, so it's worth being as tense as possible
+ * about the data-matching loops.
+ */
+static void
+computeRegionBaseDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd)
{
int i,
loopEnd,
@@ -222,27 +374,508 @@ computeRegionDelta(PageData *pageData,
}
/*
+ * Align curRegion and targetRegion and return the number of mismatches
+ * or -1 if the alignment with number of mismatching positions less than
+ * or equal to maxMismatches does not exist.
+ * The algorithm guarantees to find the alignment with the least possible
+ * number of mismathing positions or return that such least number is greater
+ * than maxMismatches.
+ *
+ * For a good introduction to the subject, read about the "Levenshtein
+ * distance" in Wikipedia.
+ *
+ * The basic algorithm is described in:
+ * "An O(ND) Difference Algorithm and its Variations", Eugene W. Myers,
+ * Algorithmica Vol. 1, 1986, pp. 251-266,
+ * <http://dx.doi.org/10.1007/BF01840446>,
+ * PDF: <http://mail.xmailserver.net/diff2.pdf>.
+ * See especially section 3, which describes the variation used below.
+ *
+ * This variation requires O(N + D ^ 2) memory and has time complexity O(ND).
+ * We choose it because it is faster than described in section 4.2 modification
+ * with O(N + D) memory requirement.
+ *
+ * The only modification we made to the original algorithm is the introduction
+ * of REPLACE operations, while in the original algorithm only INSERT and
+ * REMOVE are considered. This introduction doesn't affect time and memory
+ * complexity of the algorithm.
+ */
+static int
+alignRegions(const char *curRegion, const char *targetRegion,
+ int curRegionLen, int targetRegionLen,
+ uint8 maxMismatches)
+{
+ /* Number of mismatches */
+ int m;
+
+ /* Difference between curRegion and targetRegion prefix lengths */
+ int k;
+
+ /* Curbuf and targetRegion prefix lengths */
+ int i,
+ j;
+
+ /* Number of mismathes in the answer */
+ int numMismatches = -1;
+
+ /*
+ * If lengths differ too much, there is no alignment with a small number
+ * of mismatches.
+ */
+ if (!(-maxMismatches < curRegionLen - targetRegionLen &&
+ curRegionLen - targetRegionLen < maxMismatches))
+ return -1;
+
+ /*
+ * V is an array to store the values of dynamic programming. The first
+ * dimension corresponds to m, i. e. to the number of performed editing
+ * operations, and the second one is for k + m, where k is the number of a
+ * diagonal. A diagonal numbered k is such points (i, j) where i - j = k.
+ * Here i means the length of curRegion prefix and j means the length of
+ * targetRegion prefix. V[m][m + k] is the length of the longest prefix of
+ * curRegion i which can be aligned with the prefix of length j of
+ * targetRegion using m editing operations. In the loop below we
+ * initialize V[0][0] and then compute V[m][m + k] based on, if defined,
+ * V[m - 1][m + k - 1], V[m - 1][m + k], and V[m - 1][m + k + 1]. V[m][m +
+ * k] is undefined if k < -m or k > m.
+ */
+ V[0][0] = 0;
+
+ /* Find the longest path with the given number of mismatches */
+ for (m = 0; m <= maxMismatches; ++m)
+ {
+ /*
+ * Find the largest prefix alignment with the given number of
+ * mismatches and the given diagonal, i. e. difference between
+ * curRegion and targetRegion prefix lengths.
+ */
+ for (k = -m; k <= m; ++k)
+ {
+ /* Dynamic programming recurrent step */
+ if (m > 0)
+ {
+ i = -1;
+ if (k != -m && k != m &&
+ V[m - 1][m - 1 + k] + 1 > i)
+ {
+ i = V[m - 1][m - 1 + k] + 1;
+ prevDiag[m][m + k] = k;
+ }
+ if (k != -m && k != -m + 1 &&
+ V[m - 1][m - 1 + k - 1] + 1 > i)
+ {
+ i = V[m - 1][m - 1 + k - 1] + 1;
+ prevDiag[m][m + k] = k - 1;
+ }
+ if (k != m && k != m - 1 &&
+ V[m - 1][m - 1 + k + 1] > i)
+ {
+ i = V[m - 1][m - 1 + k + 1];
+ prevDiag[m][m + k] = k + 1;
+ }
+ }
+ else
+ i = 0;
+ j = i - k;
+
+ /* Boundary checks */
+ Assert(i >= 0);
+ Assert(j >= 0);
+
+ /* Increase the prefixes while the bytes are equal */
+ while (i < curRegionLen && j < targetRegionLen &&
+ curRegion[i] == targetRegion[j])
+ i++, j++;
+
+ /*
+ * Save the largest curRegion prefix that was aligned with given
+ * number of mismatches and difference between curRegion and
+ * targetRegion prefix lengths.
+ */
+ V[m][m + k] = i;
+
+ /* If we find the alignment, save its length and break */
+ if (i == curRegionLen && j == targetRegionLen)
+ {
+ numMismatches = m;
+ break;
+ }
+ }
+ /* Break if we find an alignment */
+ if (numMismatches != -1)
+ break;
+ }
+ /* No alignment was found */
+ if (numMismatches == -1)
+ return -1;
+
+ /*
+ * Restore the path k-s for each iteration of the main loop for the found
+ * alignment.
+ */
+ Assert(m >= 0);
+ while (m != 0)
+ {
+ Assert(-m <= k && k <= m);
+ alignmentDiag[m] = k;
+ k = prevDiag[m][m + k];
+ m--;
+ }
+ Assert(k == 0);
+ alignmentDiag[0] = 0;
+
+ return numMismatches;
+}
+
+/*
+ * Restore the mismathcing parts of the alignment based on V, alignmentDiag,
+ * and numMismacthes. Do some alignment assertions also.
+ *
+ * The compressed alignment is stored in curRegionAligned, targetRegionAligned,
+ * curRegionAlignedGap, targetRegionAlignedGap, curRegionAlignedPos, and
+ * targetRegionAlignedPos. The first two arrays contain the aligned data,
+ * the second two contain the map of align gaps in the first two arrays,
+ * and the last two arrays contain the positions of the aligned parts in
+ * the original arrays.
+ */
+int
+restoreCompactAlignment(const char *curRegion, const char *targetRegion,
+ int curRegionLen, int targetRegionLen,
+ int numMismatches)
+{
+ int i,
+ j,
+ k,
+ m;
+
+ /* The length of the equal block */
+ int curLen = 0;
+
+ /* Result alignment length */
+ int resLen = 0;
+
+ /* Maximal possible result alignment length */
+ int maxResLen = Min(curRegionLen, targetRegionLen) + numMismatches;
+
+ /* Keep compiler quiet */
+ if (curLen != 0)
+ curLen = maxResLen;
+
+ /* Check whether the first equal block is computed correctly */
+ curLen = V[0][0];
+ Assert(curLen >= 0);
+ Assert(resLen + curLen <= maxResLen);
+ Assert(memcmp(curRegion, targetRegion, curLen) == 0);
+
+ /* Restore the alignment */
+ for (m = 1; m <= numMismatches; ++m)
+ {
+ /* Initialize the variables for the block */
+ int dk = alignmentDiag[m] - alignmentDiag[m - 1];
+ int prevDiag = alignmentDiag[m - 1];
+
+ k = alignmentDiag[m];
+ i = V[m - 1][m - 1 + prevDiag];
+ j = i - prevDiag;
+ /* Check state consistency */
+ Assert(0 <= i && i <= curRegionLen);
+ Assert(0 <= j && j <= targetRegionLen);
+
+ /* Check the block operation correctness */
+ Assert(dk == -1 || i < curRegionLen);
+ Assert(dk == 1 || j < targetRegionLen);
+ Assert(-1 <= dk && dk <= 1);
+ Assert(resLen + 1 <= maxResLen);
+
+ /* Do the alignment operation of the block */
+ curRegionAlignedPos[resLen] = i;
+ targetRegionAlignedPos[resLen] = j;
+ if (dk == 1 || dk == 0)
+ {
+ curRegionAlignedGap[resLen] = false;
+ curRegionAligned[resLen] = curRegion[i++];
+ }
+ else
+ curRegionAlignedGap[resLen] = true;
+ if (dk == 0 || dk == -1)
+ {
+ targetRegionAlignedGap[resLen] = false;
+ targetRegionAligned[resLen] = targetRegion[j++];
+ }
+ else
+ targetRegionAlignedGap[resLen] = true;
+ resLen++;
+
+ /* Compute the size of the equal part of the block */
+ curLen = V[m][m + k] - i;
+
+ /* Check whether the equal part of the block is computed correctly */
+ Assert(curLen >= 0);
+ Assert(resLen + curLen <= maxResLen);
+ Assert(memcmp(&curRegion[i], &targetRegion[j], curLen) == 0);
+ }
+
+ return resLen;
+}
+
+/*
+ * Try to build a short alignment in order to produce a short diff delta.
+ * If fails, return false, otherwise return true and write the delta to
+ * pageData->delta.
+ */
+static bool
+computeRegionDiffDelta(PageData *pageData,
+ const char *curpage, const char *targetpage,
+ int targetStart, int targetEnd,
+ int validStart, int validEnd,
+ uint8 maxMismatches)
+{
+ char *ptr = pageData->delta + pageData->deltaLen;
+ int i,
+ j;
+ char type;
+ uint8 len;
+ OffsetNumber start;
+ OffsetNumber tmp;
+
+ int numMismatches;
+ int alignmentLength;
+
+ int curRegionLen = validEnd - validStart;
+ int targetRegionLen = targetEnd - targetStart;
+
+ numMismatches = alignRegions(&curpage[validStart],
+ &targetpage[targetStart],
+ curRegionLen,
+ targetRegionLen,
+ maxMismatches);
+ Assert(numMismatches <= maxMismatches);
+
+ /* If no proper alignment was found return false */
+ if (numMismatches < 0)
+ return false;
+
+ /* Restore the alignment in a compact form */
+ alignmentLength = restoreCompactAlignment(&curpage[validStart],
+ &targetpage[targetStart],
+ curRegionLen,
+ targetRegionLen,
+ numMismatches);
+
+ /*
+ * Translate the alignment into the set of instructions for transformation
+ * from curRegion into targetRegion, and write these instructions into
+ * pageData->delta.
+ */
+
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + sizeof(type) + 2 * sizeof(tmp) <= MAX_DELTA_SIZE);
+
+ /* Check whether the region is the upper or the lower part of the page */
+ Assert((validStart == 0 && targetStart == 0) ||
+ (validEnd == BLCKSZ && targetEnd == BLCKSZ));
+
+ /* Write start and end indexes of the buffers */
+ if (validStart == 0 && targetStart == 0)
+ {
+ /* We are in the upper part, there is no need to store Starts */
+ type = UPPER_REGION;
+ writeToPtr(ptr, type);
+ tmp = validEnd;
+ writeToPtr(ptr, tmp);
+ tmp = targetEnd;
+ writeToPtr(ptr, tmp);
+ }
+ else
+ {
+ /* We are in the lower part, there is no need to store Ends */
+ type = LOWER_REGION;
+ writeToPtr(ptr, type);
+ tmp = validStart;
+ writeToPtr(ptr, tmp);
+ tmp = targetStart;
+ writeToPtr(ptr, tmp);
+ }
+
+ /* Transform the alignment into the set of instructions */
+ for (i = 0; i < alignmentLength; ++i)
+ {
+ /* Verify the alignment */
+ Assert(!curRegionAlignedGap[i] || !targetRegionAlignedGap[i]);
+ Assert(curRegionAligned[i] != targetRegionAligned[i] ||
+ curRegionAlignedGap[i] || targetRegionAlignedGap[i]);
+
+ /* Determine the type of the instruction */
+ if (curRegionAlignedGap[i])
+ type = DIFF_INSERT;
+ else if (targetRegionAlignedGap[i])
+ type = DIFF_REMOVE;
+ else
+ type = DIFF_REPLACE;
+
+ /* Find the end of the block of the same instructions */
+ j = i + 1;
+ while (j < alignmentLength)
+ {
+ bool sameBlock;
+
+ sameBlock = (
+ (curRegionAlignedPos[j] <=
+ curRegionAlignedPos[j - 1] + 1) &&
+ (targetRegionAlignedPos[j] <=
+ targetRegionAlignedPos[j - 1] + 1)
+ );
+
+ switch (type)
+ {
+ case DIFF_INSERT:
+ sameBlock &= (curRegionAlignedGap[j]);
+ break;
+ case DIFF_REMOVE:
+ sameBlock &= (targetRegionAlignedGap[j]);
+ break;
+ case DIFF_REPLACE:
+ sameBlock &= (!curRegionAlignedGap[j] &&
+ !targetRegionAlignedGap[j] &&
+ (curRegionAligned[j] !=
+ targetRegionAligned[j]));
+ break;
+ default:
+ elog(ERROR, "unrecognized delta operation type: %d", type);
+ break;
+ }
+ if (sameBlock)
+ j++;
+ else
+ break;
+ }
+ len = j - i;
+
+ start = curRegionAlignedPos[i];
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + sizeof(type) +
+ sizeof(len) + sizeof(start) <= MAX_DELTA_SIZE);
+ /* Write the header for instruction */
+ writeToPtr(ptr, type);
+ writeToPtr(ptr, len);
+ writeToPtr(ptr, start);
+
+ /* Write instruction data and go to the end of the block */
+ if (type != DIFF_REMOVE)
+ {
+ /* Verify we have enough space */
+ Assert(pageData->deltaLen + len <= MAX_DELTA_SIZE);
+ while (i < j)
+ {
+ char c = targetRegionAligned[i++];
+
+ writeToPtr(ptr, c);
+ }
+ }
+ else
+ i = j;
+ i--;
+ }
+
+ pageData->deltaLen = ptr - pageData->delta;
+
+ return true;
+}
+
+/*
+ * Return whether pageData->delta contains diff deltas or not.
+ */
+static bool
+pageDataContainsDiffDelta(PageData *pageData)
+{
+ char *ptr = pageData->delta + sizeof(bool);
+ char *end = pageData->delta + pageData->deltaLen;
+ char header;
+ int length;
+
+ while (ptr < end)
+ {
+ readFromPtr(ptr, header);
+ readFromPtr(ptr, length);
+
+ if (header == DIFF_DELTA)
+ return true;
+ ptr += length;
+ }
+ return false;
+}
+
+/*
+ * Downgrade pageData->delta to base delta format.
+ *
+ * Only base diffs are allowed to perform the transformation.
+ */
+static void
+downgradeDeltaToBaseFormat(PageData *pageData)
+{
+ char *ptr = pageData->delta;
+ char *end = pageData->delta + pageData->deltaLen;
+ char *cur;
+ bool containsDiffDelta;
+ char header;
+ int length;
+ int newDeltaLength = 0;
+
+ /* Check whether containsDiffDelta is false */
+ readFromPtr(ptr, containsDiffDelta);
+ Assert(!containsDiffDelta);
+
+ cur = ptr;
+ while (ptr < end)
+ {
+ readFromPtr(ptr, header);
+ readFromPtr(ptr, length);
+
+ /* Check whether the region delta is base delta */
+ Assert(header == BASE_DELTA);
+ newDeltaLength += length;
+
+ memmove(cur, ptr, length);
+ cur += length;
+ ptr += length;
+ }
+ pageData->deltaLen = newDeltaLength;
+}
+
+/*
* Compute the XLOG delta record needed to transform curpage into targetpage,
* and store it in pageData's delta field.
*/
static void
computeDelta(PageData *pageData, Page curpage, Page targetpage)
{
+ bool *containsDiffDelta = pageData->delta;
int targetLower = ((PageHeader) targetpage)->pd_lower,
targetUpper = ((PageHeader) targetpage)->pd_upper,
curLower = ((PageHeader) curpage)->pd_lower,
curUpper = ((PageHeader) curpage)->pd_upper;
- pageData->deltaLen = 0;
+ pageData->deltaLen = sizeof(bool);
/* Compute delta records for lower part of page ... */
computeRegionDelta(pageData, curpage, targetpage,
0, targetLower,
- 0, curLower);
+ 0, curLower,
+ pageData->compressParams.lowerMaxMismatches);
/* ... and for upper part, ignoring what's between */
computeRegionDelta(pageData, curpage, targetpage,
targetUpper, BLCKSZ,
- curUpper, BLCKSZ);
+ curUpper, BLCKSZ,
+ pageData->compressParams.upperMaxMismatches);
+
+ /*
+ * Set first byte to true if at least one of the region deltas is diff
+ * delta. Otherwise set first byte to false and downgrade all regions to
+ * base format without extra headers.
+ */
+ *containsDiffDelta = pageDataContainsDiffDelta(pageData);
+ if (!(*containsDiffDelta))
+ downgradeDeltaToBaseFormat(pageData);
/*
* If xlog debug is enabled, then check produced delta. Result of delta
@@ -291,11 +924,13 @@ GenericXLogStart(Relation relation)
* is what the caller should modify.
*
* If the buffer is already registered, just return its existing entry.
- * (It's not very clear what to do with the flags in such a case, but
- * for now we stay with the original flags.)
+ * (It's not very clear what to do with the flags and parameters in such
+ * a case, but for now we stay with the original flags and parameters.)
*/
Page
-GenericXLogRegisterBuffer(GenericXLogState *state, Buffer buffer, int flags)
+GenericXLogRegisterBufferEx(GenericXLogState *state,
+ Buffer buffer, int flags,
+ PageXLogCompressParams compressParams)
{
int block_id;
@@ -309,6 +944,7 @@ GenericXLogRegisterBuffer(GenericXLogState *state, Buffer buffer, int flags)
/* Empty slot, so use it (there cannot be a match later) */
page->buffer = buffer;
page->flags = flags;
+ page->compressParams = compressParams;
memcpy(page->image, BufferGetPage(buffer), BLCKSZ);
return (Page) page->image;
}
@@ -329,6 +965,22 @@ GenericXLogRegisterBuffer(GenericXLogState *state, Buffer buffer, int flags)
}
/*
+ * An alias for GenericXLogRegisterBufferEx with default parameters
+ * which are optimal for Bloom and RUM indexes.
+ * Left for backward compatibility.
+ */
+Page
+GenericXLogRegisterBuffer(GenericXLogState *state, Buffer buffer, int flags)
+{
+ PageXLogCompressParams defaultParameters;
+
+ defaultParameters.upperMaxMismatches = 0;
+ defaultParameters.lowerMaxMismatches = 24;
+ return GenericXLogRegisterBufferEx(state, buffer, flags,
+ defaultParameters);
+}
+
+/*
* Apply changes represented by GenericXLogState to the actual buffers,
* and emit a generic xlog record.
*/
@@ -451,12 +1103,58 @@ GenericXLogAbort(GenericXLogState *state)
/*
* Apply delta to given page image.
+ *
+ * Read blocks of instructions and apply them based on their type:
+ * BASE_DELTA or DIFF_DELTA.
*/
static void
applyPageRedo(Page page, const char *delta, Size deltaSize)
{
const char *ptr = delta;
const char *end = delta + deltaSize;
+ char header;
+ int length;
+ bool containsDiffDelta;
+
+ /* If page delta is base delta, apply it. */
+ readFromPtr(ptr, containsDiffDelta);
+ if (!containsDiffDelta)
+ {
+ applyPageBaseRedo(page, ptr, end - ptr);
+ return;
+ }
+
+ /* Otherwise apply each region delta. */
+ while (ptr < end)
+ {
+ readFromPtr(ptr, header);
+ readFromPtr(ptr, length);
+
+ switch (header)
+ {
+ case DIFF_DELTA:
+ ptr = applyPageDiffRedo(page, ptr, length);
+ break;
+ case BASE_DELTA:
+ ptr = applyPageBaseRedo(page, ptr, length);
+ break;
+ default:
+ elog(ERROR,
+ "unrecognized delta type: %d",
+ header);
+ break;
+ }
+ }
+}
+
+/*
+ * Apply base delta to given page image.
+ */
+static const char *
+applyPageBaseRedo(Page page, const char *delta, Size deltaSize)
+{
+ const char *ptr = delta;
+ const char *end = delta + deltaSize;
while (ptr < end)
{
@@ -472,6 +1170,96 @@ applyPageRedo(Page page, const char *delta, Size deltaSize)
ptr += length;
}
+ return ptr;
+}
+
+/*
+ * Apply diff delta to given page image.
+ */
+static const char *
+applyPageDiffRedo(Page page, const char *delta, Size deltaSize)
+{
+ const char *ptr = delta;
+ const char *end = delta + deltaSize;
+ char type;
+ uint8 len;
+ OffsetNumber targetStart,
+ targetEnd;
+ OffsetNumber validStart,
+ validEnd;
+ int i,
+ j;
+ OffsetNumber start;
+
+ /* Read start and end indexes of the buffers */
+ validStart = 0;
+ validEnd = BLCKSZ;
+ targetStart = 0;
+ targetEnd = BLCKSZ;
+ readFromPtr(ptr, type);
+ switch (type)
+ {
+ case UPPER_REGION:
+ readFromPtr(ptr, validEnd);
+ readFromPtr(ptr, targetEnd);
+ break;
+ case LOWER_REGION:
+ readFromPtr(ptr, validStart);
+ readFromPtr(ptr, targetStart);
+ break;
+ default:
+ elog(ERROR,
+ "unrecognized region type: %d",
+ type);
+ break;
+ }
+
+ /* Read and apply the instructions */
+ i = 0, j = 0;
+ while (ptr < end)
+ {
+ /* Read the header of the current instruction */
+ readFromPtr(ptr, type);
+ readFromPtr(ptr, len);
+ readFromPtr(ptr, start);
+
+ /* Copy the data before current instruction to buffer */
+ memcpy(&localPage[j], page + validStart + i, start - i);
+ j += start - i;
+ i = start;
+
+ /* Apply the instruction */
+ switch (type)
+ {
+ case DIFF_INSERT:
+ memcpy(&localPage[j], ptr, len);
+ ptr += len;
+ j += len;
+ break;
+ case DIFF_REMOVE:
+ i += len;
+ break;
+ case DIFF_REPLACE:
+ memcpy(&localPage[j], ptr, len);
+ i += len;
+ j += len;
+ ptr += len;
+ break;
+ default:
+ elog(ERROR,
+ "unrecognized delta instruction type: %d",
+ type);
+ break;
+ }
+ }
+
+ /* Copy the data after the last instruction */
+ memcpy(&localPage[j], page + validStart + i, validEnd - validStart - i);
+ j += validEnd - validStart - i;
+ i = validEnd - validStart;
+
+ memcpy(page + targetStart, localPage, j);
+ return ptr;
}
/*
diff --git a/src/include/access/generic_xlog.h b/src/include/access/generic_xlog.h
index b23e1f6..a8e406b 100644
--- a/src/include/access/generic_xlog.h
+++ b/src/include/access/generic_xlog.h
@@ -25,6 +25,17 @@
/* Flag bits for GenericXLogRegisterBuffer */
#define GENERIC_XLOG_FULL_IMAGE 0x0001 /* write full-page image */
+/* Struct of generic xlog compression parameters for a single page */
+typedef struct
+{
+ /*
+ * maximal number of mismatches for diff delta for the upper part of the
+ * page. Zero value disables diff delta for the part
+ */
+ uint8 upperMaxMismatches;
+ uint8 lowerMaxMismatches; /* the same for the lower part */
+} PageXLogCompressParams;
+
/* state of generic xlog record construction */
struct GenericXLogState;
typedef struct GenericXLogState GenericXLogState;
@@ -33,6 +44,8 @@ typedef struct GenericXLogState GenericXLogState;
extern GenericXLogState *GenericXLogStart(Relation relation);
extern Page GenericXLogRegisterBuffer(GenericXLogState *state, Buffer buffer,
int flags);
+extern Page GenericXLogRegisterBufferEx(GenericXLogState *state, Buffer buffer,
+ int flags, PageXLogCompressParams compressParams);
extern XLogRecPtr GenericXLogFinish(GenericXLogState *state);
extern void GenericXLogAbort(GenericXLogState *state);
[text/plain] postgresql.conf (22.2K, ../../[email protected]/3-postgresql.conf)
download | inline:
# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
# name = value
#
# (The "=" is optional.) Whitespace may be used. Comments are introduced with
# "#" anywhere on a line. The complete list of parameter names and allowed
# values can be found in the PostgreSQL documentation.
#
# The commented-out settings shown in this file represent the default values.
# Re-commenting a setting is NOT sufficient to revert it to the default value;
# you need to reload the server.
#
# This file is read on server startup and when the server receives a SIGHUP
# signal. If you edit the file on a running system, you have to SIGHUP the
# server for the changes to take effect, run "pg_ctl reload", or execute
# "SELECT pg_reload_conf()". Some parameters, which are marked below,
# require a server shutdown and restart to take effect.
#
# Any parameter can also be given as a command-line option to the server, e.g.,
# "postgres -c log_connections=on". Some parameters can be changed at run time
# with the "SET" SQL command.
#
# Memory units: kB = kilobytes Time units: ms = milliseconds
# MB = megabytes s = seconds
# GB = gigabytes min = minutes
# TB = terabytes h = hours
# d = days
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable, represented here as ConfigDir.
#data_directory = 'ConfigDir' # use data in another directory
# (change requires restart)
#hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
# (change requires restart)
#ident_file = 'ConfigDir/pg_ident.conf' # ident configuration file
# (change requires restart)
# If external_pid_file is not explicitly set, no extra PID file is written.
#external_pid_file = '' # write an extra PID file
# (change requires restart)
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
#listen_addresses = 'localhost' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost'; use '*' for all
# (change requires restart)
#port = 5845 # (change requires restart)
max_connections = 100 # (change requires restart)
#superuser_reserved_connections = 3 # (change requires restart)
#unix_socket_directories = '/tmp' # comma-separated list of directories
# (change requires restart)
#unix_socket_group = '' # (change requires restart)
#unix_socket_permissions = 0777 # begin with 0 to use octal notation
# (change requires restart)
#bonjour = off # advertise server via Bonjour
# (change requires restart)
#bonjour_name = '' # defaults to the computer name
# (change requires restart)
# - Security and Authentication -
#authentication_timeout = 1min # 1s-600s
#ssl = off
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_dh_params_file = ''
#ssl_cert_file = 'server.crt'
#ssl_key_file = 'server.key'
#ssl_ca_file = ''
#ssl_crl_file = ''
#password_encryption = md5 # md5 or scram-sha-256
#db_user_namespace = off
#row_security = on
# GSSAPI using Kerberos
#krb_server_keyfile = ''
#krb_caseins_users = off
# - TCP Keepalives -
# see "man 7 tcp" for details
#tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds;
# 0 selects the system default
#tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds;
# 0 selects the system default
#tcp_keepalives_count = 0 # TCP_KEEPCNT;
# 0 selects the system default
#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------
# - Memory -
shared_buffers = 1024MB # min 128kB
# (change requires restart)
#huge_pages = try # on, off, or try
# (change requires restart)
#temp_buffers = 8MB # min 800kB
#max_prepared_transactions = 0 # zero disables the feature
# (change requires restart)
# Caution: it is not advisable to set max_prepared_transactions nonzero unless
# you actively intend to use prepared transactions.
#work_mem = 4MB # min 64kB
#maintenance_work_mem = 64MB # min 1MB
#replacement_sort_tuples = 150000 # limits use of replacement selection sort
#autovacuum_work_mem = -1 # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB # min 100kB
dynamic_shared_memory_type = posix # the default is the first option
# supported by the operating system:
# posix
# sysv
# windows
# mmap
# use none to disable dynamic shared memory
# (change requires restart)
# - Disk -
#temp_file_limit = -1 # limits per-process temp file space
# in kB, or -1 for no limit
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
# (change requires restart)
#shared_preload_libraries = '' # (change requires restart)
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0 # 0-100 milliseconds
#vacuum_cost_page_hit = 1 # 0-10000 credits
#vacuum_cost_page_miss = 10 # 0-10000 credits
#vacuum_cost_page_dirty = 20 # 0-10000 credits
#vacuum_cost_limit = 200 # 1-10000 credits
# - Background Writer -
bgwriter_delay = 20ms # 10-10000ms between rounds
bgwriter_lru_maxpages = 800 # 0-1000 max buffers written/round
bgwriter_lru_multiplier = 8.0 # 0-10.0 multiplier on buffers scanned/round
#bgwriter_flush_after = 512kB # measured in pages, 0 disables
# - Asynchronous Behavior -
#effective_io_concurrency = 1 # 1-1000; 0 disables prefetching
#max_worker_processes = 8 # (change requires restart)
#max_parallel_workers_per_gather = 2 # taken from max_parallel_workers
#max_parallel_workers = 8 # maximum number of max_worker_processes that
# can be used in parallel queries
#old_snapshot_threshold = -1 # 1min-60d; -1 disables; 0 is immediate
# (change requires restart)
#backend_flush_after = 0 # measured in pages, 0 disables
#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------
# - Settings -
wal_level = minimal # minimal, replica, or logical
# (change requires restart)
fsync = off # flush data to disk for crash safety
# (turning this off can cause
# unrecoverable data corruption)
synchronous_commit = off # synchronization level;
# off, local, remote_write, remote_apply, or on
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
# fdatasync (default on Linux)
# fsync
# fsync_writethrough
# open_sync
full_page_writes = off # recover from partial page writes
#wal_compression = off # enable compression of full-page writes
#wal_log_hints = off # also do full page writes of non-critical updates
# (change requires restart)
#wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers
# (change requires restart)
#wal_writer_delay = 200ms # 1-10000 milliseconds
#wal_writer_flush_after = 1MB # measured in pages, 0 disables
#commit_delay = 0 # range 0-100000, in microseconds
#commit_siblings = 5 # range 1-1000
# - Checkpoints -
checkpoint_timeout = 120min # range 30s-1d
max_wal_size = 8GB
min_wal_size = 1GB
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_flush_after = 256kB # measured in pages, 0 disables
#checkpoint_warning = 30s # 0 disables
# - Archiving -
#archive_mode = off # enables archiving; off, on, or always
# (change requires restart)
#archive_command = '' # command to use to archive a logfile segment
# placeholders: %p = path of file to archive
# %f = file name only
# e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
#archive_timeout = 0 # force a logfile segment switch after this
# number of seconds; 0 disables
#------------------------------------------------------------------------------
# REPLICATION
#------------------------------------------------------------------------------
# - Sending Server(s) -
# Set these on the master and on any standby that will send replication data.
max_wal_senders = 0 # max number of walsender processes
# (change requires restart)
#wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables
#wal_sender_timeout = 60s # in milliseconds; 0 disables
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
#track_commit_timestamp = off # collect timestamp of transaction commit
# (change requires restart)
# - Master Server -
# These settings are ignored on a standby server.
#synchronous_standby_names = '' # standby servers that provide sync rep
# method to choose sync standbys, number of sync standbys,
# and comma-separated list of application_name
# from standby(s); '*' = all
#vacuum_defer_cleanup_age = 0 # number of xacts by which cleanup is delayed
# - Standby Servers -
# These settings are ignored on a master server.
#hot_standby = on # "off" disallows queries during recovery
# (change requires restart)
#max_standby_archive_delay = 30s # max delay before canceling queries
# when reading WAL from archive;
# -1 allows indefinite delay
#max_standby_streaming_delay = 30s # max delay before canceling queries
# when reading streaming WAL;
# -1 allows indefinite delay
#wal_receiver_status_interval = 10s # send replies at least this often
# 0 disables
#hot_standby_feedback = off # send info from standby to prevent
# query conflicts
#wal_receiver_timeout = 60s # time that receiver waits for
# communication from master
# in milliseconds; 0 disables
#wal_retrieve_retry_interval = 5s # time to wait before retrying to
# retrieve WAL after a failed attempt
# - Subscribers -
# These settings are ignored on a publisher.
#max_logical_replication_workers = 4 # taken from max_worker_processes
# (change requires restart)
#max_sync_workers_per_subscription = 2 # taken from max_logical_replication_workers
#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on
# - Planner Cost Constants -
#seq_page_cost = 1.0 # measured on an arbitrary scale
#random_page_cost = 4.0 # same scale as above
#cpu_tuple_cost = 0.01 # same scale as above
#cpu_index_tuple_cost = 0.005 # same scale as above
#cpu_operator_cost = 0.0025 # same scale as above
#parallel_tuple_cost = 0.1 # same scale as above
#parallel_setup_cost = 1000.0 # same scale as above
#min_parallel_table_scan_size = 8MB
#min_parallel_index_scan_size = 512kB
#effective_cache_size = 4GB
# - Genetic Query Optimizer -
#geqo = on
#geqo_threshold = 12
#geqo_effort = 5 # range 1-10
#geqo_pool_size = 0 # selects default based on effort
#geqo_generations = 0 # selects default based on effort
#geqo_selection_bias = 2.0 # range 1.5-2.0
#geqo_seed = 0.0 # range 0.0-1.0
# - Other Planner Options -
#default_statistics_target = 100 # range 1-10000
#constraint_exclusion = partition # on, off, or partition
#cursor_tuple_fraction = 0.1 # range 0.0-1.0
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
# JOIN clauses
#force_parallel_mode = off
#------------------------------------------------------------------------------
# ERROR REPORTING AND LOGGING
#------------------------------------------------------------------------------
# - Where to Log -
#log_destination = 'stderr' # Valid values are combinations of
# stderr, csvlog, syslog, and eventlog,
# depending on platform. csvlog
# requires logging_collector to be on.
# This is used when logging to stderr:
#logging_collector = off # Enable capturing of stderr and csvlog
# into log files. Required to be on for
# csvlogs.
# (change requires restart)
# These are only used if logging_collector is on:
#log_directory = 'log' # directory where log files are written,
# can be absolute or relative to PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern,
# can include strftime() escapes
#log_file_mode = 0600 # creation mode for log files,
# begin with 0 to use octal notation
#log_truncate_on_rotation = off # If on, an existing log file with the
# same name as the new log file will be
# truncated rather than appended to.
# But such truncation only occurs on
# time-driven rotation, not on restarts
# or size-driven rotation. Default is
# off, meaning append to existing files
# in all cases.
#log_rotation_age = 1d # Automatic rotation of logfiles will
# happen after that time. 0 disables.
#log_rotation_size = 10MB # Automatic rotation of logfiles will
# happen after that much log output.
# 0 disables.
# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'
#syslog_sequence_numbers = on
#syslog_split_messages = on
# This is only relevant when logging to eventlog (win32):
# (change requires restart)
#event_source = 'PostgreSQL'
# - When to Log -
#client_min_messages = notice # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# log
# notice
# warning
# error
#log_min_messages = warning # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic
#log_min_error_statement = error # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic (effectively off)
#log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements
# and their durations, > 0 logs only
# statements running at least this number
# of milliseconds
# - What to Log -
#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_error_verbosity = default # terse, default, or verbose messages
#log_hostname = off
#log_line_prefix = '%m [%p] ' # special values:
# %a = application name
# %u = user name
# %d = database name
# %r = remote host and port
# %h = remote host
# %p = process ID
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %n = timestamp with milliseconds (as a Unix epoch)
# %i = command tag
# %e = SQL state
# %c = session ID
# %l = session line number
# %s = session start timestamp
# %v = virtual transaction ID
# %x = transaction ID (0 if none)
# %q = stop here in non-session
# processes
# %% = '%'
# e.g. '<%u%%%d> '
#log_lock_waits = off # log lock waits >= deadlock_timeout
#log_statement = 'none' # none, ddl, mod, all
#log_replication_commands = off
#log_temp_files = -1 # log temporary files equal or larger
# than the specified size in kilobytes;
# -1 disables, 0 logs all temp files
log_timezone = 'W-SU'
# - Process Title -
#cluster_name = '' # added to process titles if nonempty
# (change requires restart)
#update_process_title = on
#------------------------------------------------------------------------------
# RUNTIME STATISTICS
#------------------------------------------------------------------------------
# - Query/Index Statistics Collector -
#track_activities = on
#track_counts = on
#track_io_timing = off
#track_functions = none # none, pl, all
#track_activity_query_size = 1024 # (change requires restart)
#stats_temp_directory = 'pg_stat_tmp'
# - Statistics Monitoring -
#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off
#------------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------------------------------------
#autovacuum = on # Enable autovacuum subprocess? 'on'
# requires track_counts to also be on.
#log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and
# their durations, > 0 logs only
# actions running at least this number
# of milliseconds.
#autovacuum_max_workers = 3 # max number of autovacuum subprocesses
# (change requires restart)
#autovacuum_naptime = 1min # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
# vacuum
#autovacuum_analyze_threshold = 50 # min number of row updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_multixact_freeze_max_age = 400000000 # maximum multixact age
# before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for
# autovacuum, in milliseconds;
# -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit
#------------------------------------------------------------------------------
# CLIENT CONNECTION DEFAULTS
#------------------------------------------------------------------------------
# - Statement Behavior -
#search_path = '"$user", public' # schema names
#default_tablespace = '' # a tablespace name, '' uses the default
#temp_tablespaces = '' # a list of tablespace names, '' uses
# only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#default_transaction_deferrable = off
#session_replication_role = 'origin'
#statement_timeout = 0 # in milliseconds, 0 is disabled
#lock_timeout = 0 # in milliseconds, 0 is disabled
#idle_in_transaction_session_timeout = 0 # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#vacuum_multixact_freeze_min_age = 5000000
#vacuum_multixact_freeze_table_age = 150000000
#bytea_output = 'hex' # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'
#gin_fuzzy_search_limit = 0
#gin_pending_list_limit = 4MB
# - Locale and Formatting -
datestyle = 'iso, dmy'
#intervalstyle = 'postgres'
timezone = 'W-SU'
#timezone_abbreviations = 'Default' # Select the set of available time zone
# abbreviations. Currently, there are
# Default
# Australia (historical usage)
# India
# You can create your own file in
# share/timezonesets/.
#extra_float_digits = 0 # min -15, max 3
#client_encoding = sql_ascii # actually, defaults to database
# encoding
# These settings are initialized by initdb, but they can be changed.
lc_messages = 'en_US.UTF-8' # locale for system error message
# strings
lc_monetary = 'en_US.UTF-8' # locale for monetary formatting
lc_numeric = 'en_US.UTF-8' # locale for number formatting
lc_time = 'en_US.UTF-8' # locale for time formatting
# default configuration for text search
default_text_search_config = 'pg_catalog.english'
# - Other Defaults -
#dynamic_library_path = '$libdir'
#local_preload_libraries = ''
#session_preload_libraries = ''
#------------------------------------------------------------------------------
# LOCK MANAGEMENT
#------------------------------------------------------------------------------
#deadlock_timeout = 1s
#max_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_transaction = 64 # min 10
# (change requires restart)
#max_pred_locks_per_relation = -2 # negative values mean
# (max_pred_locks_per_transaction
# / -max_pred_locks_per_relation) - 1
#max_pred_locks_per_page = 2 # min 0
#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------
# - Previous PostgreSQL Versions -
#array_nulls = on
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = on
#lo_compat_privileges = off
#operator_precedence_warning = off
#quote_all_identifiers = off
#standard_conforming_strings = on
#synchronize_seqscans = on
# - Other Platforms and Clients -
#transform_null_equals = off
#------------------------------------------------------------------------------
# ERROR HANDLING
#------------------------------------------------------------------------------
#exit_on_error = off # terminate session on any error?
#restart_after_crash = on # reinitialize after backend crash?
#------------------------------------------------------------------------------
# CONFIG FILE INCLUDES
#------------------------------------------------------------------------------
# These options allow settings to be loaded from files other than the
# default postgresql.conf.
#include_dir = 'conf.d' # include files ending in '.conf' from
# directory 'conf.d'
#include_if_exists = 'exists.conf' # include file only if it exists
#include = 'special.conf' # include file
#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------
# Add settings for extensions here
[application/sql] test00.sql (1.7K, ../../[email protected]/4-test00.sql)
download
[application/sql] test01.sql (1.7K, ../../[email protected]/5-test01.sql)
download
[application/x-shellscript] test_correctness.sh (1.6K, ../../[email protected]/6-test_correctness.sh)
download
[application/x-shellscript] total_test.sh (6.9K, ../../[email protected]/7-total_test.sh)
download
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v30 10/11] Preserve pg_stat_file() isdir..
@ 2020-11-29 04:29 Justin Pryzby <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Justin Pryzby @ 2020-11-29 04:29 UTC (permalink / raw)
..per Tom's suggestion
---
src/backend/utils/adt/genfile.c | 15 ++++++++++++---
src/include/catalog/pg_proc.dat | 12 ++++++------
src/test/regress/expected/misc_functions.out | 4 ++--
3 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/src/backend/utils/adt/genfile.c b/src/backend/utils/adt/genfile.c
index 10bcb0b049..0f42714d90 100644
--- a/src/backend/utils/adt/genfile.c
+++ b/src/backend/utils/adt/genfile.c
@@ -470,11 +470,12 @@ pg_stat_file(PG_FUNCTION_ARGS)
text *filename_t = PG_GETARG_TEXT_PP(0);
char *filename;
struct stat fst;
- Datum values[6];
- bool nulls[6];
+ Datum values[7];
+ bool nulls[7];
HeapTuple tuple;
TupleDesc tupdesc;
bool missing_ok = false;
+ char type;
/* check the optional argument */
if (PG_NARGS() == 2)
@@ -496,7 +497,7 @@ pg_stat_file(PG_FUNCTION_ARGS)
* This record type had better match the output parameters declared for me
* in pg_proc.h.
*/
- tupdesc = CreateTemplateTupleDesc(6);
+ tupdesc = CreateTemplateTupleDesc(7);
TupleDescInitEntry(tupdesc, (AttrNumber) 1,
"size", INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2,
@@ -508,11 +509,19 @@ pg_stat_file(PG_FUNCTION_ARGS)
TupleDescInitEntry(tupdesc, (AttrNumber) 5,
"creation", TIMESTAMPTZOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 6,
+ "isdir", BOOLOID, -1, 0);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 7,
"type", CHAROID, -1, 0);
BlessTupleDesc(tupdesc);
memset(nulls, false, sizeof(nulls));
values_from_stat(&fst, filename, values, nulls);
+
+ /* For pg_stat_file, keep isdir column for backward compatibility */
+ type = DatumGetChar(values[5]);
+ values[5] = BoolGetDatum(type == 'd'); /* isdir */
+ values[6] = CharGetDatum(type); /* file type */
+
tuple = heap_form_tuple(tupdesc, values, nulls);
pfree(filename);
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 176501a87a..dfe27d2e3e 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6303,16 +6303,16 @@
{ oid => '2623', descr => 'get information about file',
proname => 'pg_stat_file', provolatile => 'v', prorettype => 'record',
proargtypes => 'text',
- proallargtypes => '{text,int8,timestamptz,timestamptz,timestamptz,timestamptz,char}',
- proargmodes => '{i,o,o,o,o,o,o}',
- proargnames => '{filename,size,access,modification,change,creation,type}',
+ proallargtypes => '{text,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool,char}',
+ proargmodes => '{i,o,o,o,o,o,o,o}',
+ proargnames => '{filename,size,access,modification,change,creation,isdir,type}',
prosrc => 'pg_stat_file_1arg' },
{ oid => '3307', descr => 'get information about file',
proname => 'pg_stat_file', provolatile => 'v', prorettype => 'record',
proargtypes => 'text bool',
- proallargtypes => '{text,bool,int8,timestamptz,timestamptz,timestamptz,timestamptz,char}',
- proargmodes => '{i,i,o,o,o,o,o,o}',
- proargnames => '{filename,missing_ok,size,access,modification,change,creation,type}',
+ proallargtypes => '{text,bool,int8,timestamptz,timestamptz,timestamptz,timestamptz,bool,char}',
+ proargmodes => '{i,i,o,o,o,o,o,o,o}',
+ proargnames => '{filename,missing_ok,size,access,modification,change,creation,isdir,type}',
prosrc => 'pg_stat_file' },
{ oid => '2624', descr => 'read text from a file',
proname => 'pg_read_file', provolatile => 'v', prorettype => 'text',
diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out
index db3d64de3b..349a549744 100644
--- a/src/test/regress/expected/misc_functions.out
+++ b/src/test/regress/expected/misc_functions.out
@@ -234,8 +234,8 @@ select pg_ls_dir('does not exist'); -- fails with missingok=false
ERROR: could not open directory "does not exist": No such file or directory
-- Check that expected columns are present
select * from pg_stat_file('.') limit 0;
- size | access | modification | change | creation | type
-------+--------+--------------+--------+----------+------
+ size | access | modification | change | creation | isdir | type
+------+--------+--------------+--------+----------+-------+------
(0 rows)
-- This tests the missing_ok parameter, which causes pg_ls_tmpdir to succeed even if the tmpdir doesn't exist yet
--
2.17.0
--ZwgA9U+XZDXt4+m+
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v30-0011-Add-recursion-option-in-pg_ls_dir_files.patch"
^ permalink raw reply [nested|flat] 14+ messages in thread
* ProcessStartupPacket(): database_name and user_name truncation
@ 2023-06-21 07:43 Drouvot, Bertrand <[email protected]>
0 siblings, 1 reply; 14+ messages in thread
From: Drouvot, Bertrand @ 2023-06-21 07:43 UTC (permalink / raw)
To: PostgreSQL Hackers <[email protected]>
Hi hackers,
Please find attached a patch to truncate (in ProcessStartupPacket())
the port->database_name and port->user_name in such a way to not break
multibyte character boundary.
Indeed, currently, one could create a database that way:
postgres=# create database ääääääääääääääääääääääääääääääää;
NOTICE: identifier "ääääääääääääääääääääääääääääääää" will be truncated to "äääääääääääääääääääääääääääääää"
CREATE DATABASE
The database name has been truncated from 64 bytes to 62 bytes thanks to pg_mbcliplen()
which ensures to not break multibyte character boundary.
postgres=# select datname, OCTET_LENGTH(datname),encoding from pg_database;
datname | octet_length | encoding
---------------------------------+--------------+----------
äääääääääääääääääääääääääääääää | 62 | 6
Trying to connect with the 64 bytes name:
$ psql -d ääääääääääääääääääääääääääääääää
psql: error: connection to server on socket "/tmp/.s.PGSQL.55448" failed: FATAL: database "äääääääääääääääääääääääääääääää" does not exist
It fails because the truncation done in ProcessStartupPacket():
"
if (strlen(port→database_name) >= NAMEDATALEN)
port→database_name[NAMEDATALEN - 1] = '\0';
"
does not take care about multibyte character boundary.
On the other hand it works with non multibyte character involved:
postgres=# create database abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijke;
NOTICE: identifier "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijke" will be truncated to "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk"
CREATE DATABASE
postgres=# select datname, OCTET_LENGTH(datname),encoding from pg_database;
datname | octet_length | encoding
-----------------------------------------------------------------+--------------+----------
abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk | 63 | 6
The database name is truncated to 63 bytes and then using the 64 bytes name would work:
$ psql -d abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijke
psql (16beta1)
Type "help" for help.
The comment in ProcessStartupPacket() states:
"
/*
* Truncate given database and user names to length of a Postgres name.
* This avoids lookup failures when overlength names are given.
*/
"
The last sentence is not right in case of mutlibyte character (as seen
in the first example).
About the patch:
As the database encoding is not known yet in ProcessStartupPacket() (
and we are even not sure the database provided does exist), the proposed
patch does not rely on pg_mbcliplen() but on pg_encoding_mbcliplen().
The proposed patch does use the client encoding that it retrieves that way:
- use the one requested in the startup packet (if we come across it)
- use the one from the locale (if we did not find a client encoding request
in the startup packet)
- use PG_SQL_ASCII (if none of the above have been satisfied)
Happy to discuss any other thoughts or suggestions if any.
With the proposed patch in place, using the first example above (and the
64 bytes name) we would get:
$ PGCLIENTENCODING=LATIN1 psql -d ääääääääääääääääääääääääääääääää
psql: error: connection to server on socket "/tmp/.s.PGSQL.55448" failed: FATAL: database "äääääääääääääääääääääääääääääää" does not exist
but this one would allow us to connect:
$ PGCLIENTENCODING=UTF8 psql -d ääääääääääääääääääääääääääääääää
psql (16beta1)
Type "help" for help.
The patch does not provide documentation update or related TAP test (but could be added
if we feel the need).
Looking forward to your feedback,
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
From 6ccb4f03f56dda9e9a2616c6e0875a97a8711d72 Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <[email protected]>
Date: Tue, 20 Jun 2023 10:26:16 +0000
Subject: [PATCH v1] multibyte truncation for database and user name
database_name and user_name truncation done in ProcessStartupPacket() do not
take care of multibyte character boundary. In case of multibyte, this somehow
breaks the initial goal to avoid lookup failures when overlength names are given.
---
src/backend/postmaster/postmaster.c | 48 ++++++++++++++++++++++++++---
1 file changed, 44 insertions(+), 4 deletions(-)
100.0% src/backend/postmaster/
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 4c49393fc5..72991c4eab 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1951,6 +1951,7 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
char *buf;
ProtocolVersion proto;
MemoryContext oldcontext;
+ int client_encoding = -1;
pq_startmsgread();
@@ -2238,6 +2239,18 @@ retry1:
{
port->application_name = pg_clean_ascii(valptr, 0);
}
+ /* Record the client_encoding if we come across it */
+ else if (strcmp(nameptr, "client_encoding") == 0)
+ {
+ client_encoding = pg_valid_client_encoding(valptr);
+
+ if (client_encoding < 0)
+ ereport(FATAL,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("invalid value for parameter \"%s\": \"%s\"",
+ "client_encoding",
+ valptr)));
+ }
}
offset = valoffset + strlen(valptr) + 1;
}
@@ -2291,13 +2304,40 @@ retry1:
}
/*
- * Truncate given database and user names to length of a Postgres name.
- * This avoids lookup failures when overlength names are given.
+ * Given the client encoding, truncate given database and user names to
+ * length of a Postgres name. This avoids lookup failures when overlength
+ * names are given.
*/
+ if (client_encoding < 0)
+ {
+ /*
+ * client_encoding has not been found in the startup packet so let's
+ * try to get it from locale.
+ */
+ client_encoding = pg_get_encoding_from_locale(NULL, true);
+
+ if (client_encoding < 0)
+ client_encoding = PG_SQL_ASCII;
+ }
+
if (strlen(port->database_name) >= NAMEDATALEN)
- port->database_name[NAMEDATALEN - 1] = '\0';
+ {
+ int newlen;
+
+ newlen = pg_encoding_mbcliplen(client_encoding, port->database_name,
+ strlen(port->database_name),
+ NAMEDATALEN - 1);
+ port->database_name[newlen] = '\0';
+ }
if (strlen(port->user_name) >= NAMEDATALEN)
- port->user_name[NAMEDATALEN - 1] = '\0';
+ {
+ int newlen;
+
+ newlen = pg_encoding_mbcliplen(client_encoding, port->user_name,
+ strlen(port->user_name),
+ NAMEDATALEN - 1);
+ port->user_name[newlen] = '\0';
+ }
if (am_walsender)
MyBackendType = B_WAL_SENDER;
--
2.34.1
Attachments:
[text/plain] v1-0001-multibyte-truncation-for-database-and-user-name.patch (2.9K, ../../[email protected]/2-v1-0001-multibyte-truncation-for-database-and-user-name.patch)
download | inline diff:
From 6ccb4f03f56dda9e9a2616c6e0875a97a8711d72 Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <[email protected]>
Date: Tue, 20 Jun 2023 10:26:16 +0000
Subject: [PATCH v1] multibyte truncation for database and user name
database_name and user_name truncation done in ProcessStartupPacket() do not
take care of multibyte character boundary. In case of multibyte, this somehow
breaks the initial goal to avoid lookup failures when overlength names are given.
---
src/backend/postmaster/postmaster.c | 48 ++++++++++++++++++++++++++---
1 file changed, 44 insertions(+), 4 deletions(-)
100.0% src/backend/postmaster/
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 4c49393fc5..72991c4eab 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1951,6 +1951,7 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
char *buf;
ProtocolVersion proto;
MemoryContext oldcontext;
+ int client_encoding = -1;
pq_startmsgread();
@@ -2238,6 +2239,18 @@ retry1:
{
port->application_name = pg_clean_ascii(valptr, 0);
}
+ /* Record the client_encoding if we come across it */
+ else if (strcmp(nameptr, "client_encoding") == 0)
+ {
+ client_encoding = pg_valid_client_encoding(valptr);
+
+ if (client_encoding < 0)
+ ereport(FATAL,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("invalid value for parameter \"%s\": \"%s\"",
+ "client_encoding",
+ valptr)));
+ }
}
offset = valoffset + strlen(valptr) + 1;
}
@@ -2291,13 +2304,40 @@ retry1:
}
/*
- * Truncate given database and user names to length of a Postgres name.
- * This avoids lookup failures when overlength names are given.
+ * Given the client encoding, truncate given database and user names to
+ * length of a Postgres name. This avoids lookup failures when overlength
+ * names are given.
*/
+ if (client_encoding < 0)
+ {
+ /*
+ * client_encoding has not been found in the startup packet so let's
+ * try to get it from locale.
+ */
+ client_encoding = pg_get_encoding_from_locale(NULL, true);
+
+ if (client_encoding < 0)
+ client_encoding = PG_SQL_ASCII;
+ }
+
if (strlen(port->database_name) >= NAMEDATALEN)
- port->database_name[NAMEDATALEN - 1] = '\0';
+ {
+ int newlen;
+
+ newlen = pg_encoding_mbcliplen(client_encoding, port->database_name,
+ strlen(port->database_name),
+ NAMEDATALEN - 1);
+ port->database_name[newlen] = '\0';
+ }
if (strlen(port->user_name) >= NAMEDATALEN)
- port->user_name[NAMEDATALEN - 1] = '\0';
+ {
+ int newlen;
+
+ newlen = pg_encoding_mbcliplen(client_encoding, port->user_name,
+ strlen(port->user_name),
+ NAMEDATALEN - 1);
+ port->user_name[newlen] = '\0';
+ }
if (am_walsender)
MyBackendType = B_WAL_SENDER;
--
2.34.1
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: ProcessStartupPacket(): database_name and user_name truncation
@ 2023-06-21 08:54 Kyotaro Horiguchi <[email protected]>
parent: Drouvot, Bertrand <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Kyotaro Horiguchi @ 2023-06-21 08:54 UTC (permalink / raw)
To: [email protected]; +Cc: [email protected]
At Wed, 21 Jun 2023 09:43:50 +0200, "Drouvot, Bertrand" <[email protected]> wrote in
> Trying to connect with the 64 bytes name:
>
> $ psql -d ääääääääääääääääääääääääääääääää
> psql: error: connection to server on socket "/tmp/.s.PGSQL.55448"
> failed: FATAL: database "äääääääääääääääääääääääääääääää" does not
> exist
IMHO, I'm not sure we should allow connections without the exact name
being provided. In that sense, I think we might want to consider
outright rejecting the estblishment of a connection when the given
database name doesn't fit the startup packet, since the database with
the exact given name cannot be found.
While it is somewhat off-topic, I cannot establish a connection if the
console encoding differs from the template database even if I provide
the identical database name. (I don't mean I want that behavior to be
"fix"ed.)
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
^ permalink raw reply [nested|flat] 14+ messages in thread
end of thread, other threads:[~2023-06-21 08:54 UTC | newest]
Thread overview: 14+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2017-11-16 17:31 ` Antonin Houska <[email protected]>
2017-11-20 07:49 ` Antonin Houska <[email protected]>
2017-11-30 02:40 ` Michael Paquier <[email protected]>
2018-01-22 21:37 ` Stephen Frost <[email protected]>
2018-02-07 15:31 ` David Steele <[email protected]>
2018-02-07 18:02 ` Markus Nullmeier <[email protected]>
2018-02-07 18:42 ` Stephen Frost <[email protected]>
2018-02-08 16:17 ` Markus Nullmeier <[email protected]>
2018-03-13 14:36 ` Oleg Ivanov <[email protected]>
2018-02-17 07:31 ` Oleg Ivanov <[email protected]>
2017-11-17 12:02 ` Arthur Silva <[email protected]>
2020-11-29 04:29 [PATCH v30 10/11] Preserve pg_stat_file() isdir.. Justin Pryzby <[email protected]>
2023-06-21 07:43 ProcessStartupPacket(): database_name and user_name truncation Drouvot, Bertrand <[email protected]>
2023-06-21 08:54 ` Re: ProcessStartupPacket(): database_name and user_name truncation Kyotaro Horiguchi <[email protected]>
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