Re: [DOCS] [ADMIN] shared_buffers and shmmax
Tom Lane wrote: > [ redirecting to pgsql-docs ] > > Valentin Bogdanov writes: > >> From: dx k9 > >> I'm trying to understand what the documentation means > >> by bytes per increment, what is the increment supposed to > >> be bytes, MB, or Kb. > > > shared_buffers is in disk block size, typically 8K, at least that's what it > > is on Linux platforms. shmmax is quite simply in bytes. > > The table the OP is looking at (table 17.2 in the 8.3 docs) predates > the ability to specify shared_buffers in KB or MB instead of > number-of-buffers. I agree it's not entirely obvious that what it > means is "multiply your setting in KB/MB by 8400/8192". Anybody have > an idea how to clarify things? I have updated the table title to be clearer. -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. + Index: doc/src/sgml/runtime.sgml === RCS file: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v retrieving revision 1.422 diff -c -c -r1.422 runtime.sgml *** doc/src/sgml/runtime.sgml 20 Nov 2008 11:48:26 - 1.422 --- doc/src/sgml/runtime.sgml 15 Dec 2008 23:22:24 - *** *** 1087,1093 Name !Approximate multiplier (bytes per increment) as of 8.3 --- 1087,1093 Name !Additional bytes per object, as of 8.3 *** *** 1119,1125 Fixed space requirements !770 kB --- 1119,1125 Fixed space requirements !770 k -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
Re: [DOCS] [ADMIN] shared_buffers and shmmax
I have added this TODO item: Rationalize the discrepancy between settings that use values in bytes and SHOW that returns the object count * http://archives.postgresql.org/pgsql-docs/2008-07/msg7.php --- Greg Sabino Mullane wrote: [ There is text before PGP section. ] > > -BEGIN PGP SIGNED MESSAGE- > Hash: RIPEMD160 > NotDashEscaped: You need GnuPG to verify this message > > > >> shared_buffers is in disk block size, typically 8K > > > The table the OP is looking at (table 17.2 in the 8.3 docs) predates > > the ability to specify shared_buffers in KB or MB instead of > > number-of-buffers. I agree it's not entirely obvious that what it > > means is "multiply your setting in KB/MB by 8400/8192". Anybody have > > an idea how to clarify things? > > Bite the bullet and start showing the buffer settings as a pure number of > bytes > everywhere, and get rid of the confusing '8kB' unit in pg_settings? Things > like > this don't help our cause: > > test=# show shared_buffers; > shared_buffers > > 24MB > (1 row) > > test=# set temp_buffers = '24MB'; > SET > > test=# show temp_buffers; > temp_buffers > -- > 3072 > > test=# select name, setting from pg_settings where name ~ 'buffers'; > name | setting > +- > shared_buffers | 3072 > temp_buffers | 3072 > wal_buffers| 8 > > test=# show wal_buffers; > wal_buffers > - > 64kB > > > -- > Greg Sabino Mullane [email protected] > End Point Corporation > PGP Key: 0x14964AC8 200807241351 > http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 > -BEGIN PGP SIGNATURE- > > iEYEAREDAAYFAkiIwYYACgkQvJuQZxSWSsiY5wCfU/tca+1JakWaMCDDRHEHk/Uj > 1rcAoMi1FNGSpJhyXWde1psygq6v3MlS > =gCPg > -END PGP SIGNATURE- > > > > -- > Sent via pgsql-docs mailing list ([email protected]) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-docs -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. + -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
Re: [DOCS] [ADMIN] shared_buffers and shmmax
Bruce Momjian wrote: > Tom Lane wrote: > > [ redirecting to pgsql-docs ] > > > > Valentin Bogdanov writes: > > >> From: dx k9 > > >> I'm trying to understand what the documentation means > > >> by bytes per increment, what is the increment supposed to > > >> be bytes, MB, or Kb. > > > > > shared_buffers is in disk block size, typically 8K, at least that's what > > > it is on Linux platforms. shmmax is quite simply in bytes. > > > > The table the OP is looking at (table 17.2 in the 8.3 docs) predates > > the ability to specify shared_buffers in KB or MB instead of > > number-of-buffers. I agree it's not entirely obvious that what it > > means is "multiply your setting in KB/MB by 8400/8192". Anybody have > > an idea how to clarify things? > > I have updated the table title to be clearer. I don't find it any clearer ... I think the missing clue is that if you specify shared_buffers values in MB, you must divide the value by block size. > *** > *** 1119,1125 > > > Fixed space requirements > !770 kB > > > > --- 1119,1125 > > > Fixed space requirements > !770 k > > > This change is wrong, why did you do it? -- Alvaro Herrerahttp://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
Re: [DOCS] [ADMIN] shared_buffers and shmmax
Alvaro Herrera wrote: > Bruce Momjian wrote: > > Tom Lane wrote: > > > [ redirecting to pgsql-docs ] > > > > > > Valentin Bogdanov writes: > > > >> From: dx k9 > > > >> I'm trying to understand what the documentation means > > > >> by bytes per increment, what is the increment supposed to > > > >> be bytes, MB, or Kb. > > > > > > > shared_buffers is in disk block size, typically 8K, at least that's > > > > what it is on Linux platforms. shmmax is quite simply in bytes. > > > > > > The table the OP is looking at (table 17.2 in the 8.3 docs) predates > > > the ability to specify shared_buffers in KB or MB instead of > > > number-of-buffers. I agree it's not entirely obvious that what it > > > means is "multiply your setting in KB/MB by 8400/8192". Anybody have > > > an idea how to clarify things? > > > > I have updated the table title to be clearer. > > I don't find it any clearer ... I think the missing clue is that if you > specify shared_buffers values in MB, you must divide the value by block > size. Well, the heading says "object" now so I thought it would suggest we are talking about objects and not bytes. > > *** > > *** 1119,1125 > > > > > > Fixed space requirements > > !770 kB > > > > > > > > --- 1119,1125 > > > > > > Fixed space requirements > > !770 k > > > > > > > > This change is wrong, why did you do it? The heading says "bytes" so having the "B" was unnecessary and possibly confusing. -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. + -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
Re: [DOCS] [ADMIN] shared_buffers and shmmax
Bruce Momjian writes: > Alvaro Herrera wrote: >> I don't find it any clearer ... I think the missing clue is that if you >> specify shared_buffers values in MB, you must divide the value by block >> size. > Well, the heading says "object" now so I thought it would suggest we are > talking about objects and not bytes. I'm with Alvaro: neither of those changes were improvements. regards, tom lane -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
Re: [DOCS] triggers on views?
Tom Lane wrote: > Robert Treat writes: > > We had a doc comment come in noting that the second paragraph seems to be > > incorrect on > > http://www.postgresql.org/docs/8.3/interactive/rules-triggers.html, > > specifically the part that says "On the other hand, a trigger that is fired > > on INSERT on a view can do the same as a rule". > > This was discussed last month: > http://archives.postgresql.org/pgsql-general/2008-06/msg00669.php OK, updated wording applied to CVS HEAD; attached. -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. + Index: doc/src/sgml/rules.sgml === RCS file: /cvsroot/pgsql/doc/src/sgml/rules.sgml,v retrieving revision 1.51 diff -c -c -r1.51 rules.sgml *** doc/src/sgml/rules.sgml 1 Feb 2007 19:10:24 - 1.51 --- doc/src/sgml/rules.sgml 16 Dec 2008 03:10:55 - *** *** 1869,1881 ! On the other hand, a trigger that is fired on ! INSERT on a view can do the same as a rule: put ! the data somewhere else and suppress the insert in the view. But ! it cannot do the same thing on UPDATE or ! DELETE, because there is no real data in the ! view relation that could be scanned, and thus the trigger would ! never get called. Only a rule will help. --- 1869,1877 ! On the other hand, a trigger cannot be created on views because ! there is no real data in a view relation; however INSERT, UPDATE, ! and DELETE rules can be created on views. -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
Re: [DOCS] [ADMIN] shared_buffers and shmmax
Tom Lane wrote: > Bruce Momjian writes: > > Alvaro Herrera wrote: > >> I don't find it any clearer ... I think the missing clue is that if you > >> specify shared_buffers values in MB, you must divide the value by block > >> size. > > > Well, the heading says "object" now so I thought it would suggest we are > > talking about objects and not bytes. > > I'm with Alvaro: neither of those changes were improvements. OK, I never got the change applied because of Alvaro's objection so there is nothing to revert. Alvaro said he has an idea for improved wording; I do not. -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. + -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
