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extend column limit with blocksize does not work 2+ messages / 2 participants [nested] [flat]
* extend column limit with blocksize does not work @ 2012-01-26 12:32 Yannick Monclin <yannick.monclin@univ-reims.fr> 2012-01-26 15:39 ` Re: extend column limit with blocksize does not work Tom Lane <tgl@sss.pgh.pa.us> 0 siblings, 1 reply; 2+ messages in thread From: Yannick Monclin @ 2012-01-26 12:32 UTC (permalink / raw) To: pgsql-admin Hi, I use the query survey software "Limesurvey", when this sofware build some complex survey, it's necessary to have more than 1600 columns in one table. So, i have used this parameter (configure --with-blocksize=32) to build my last postgresql (9.1.2). Compilation process succeed. I create a DB with initdb (i change posgresql.conf.sample --> shared_buffers = 32MB in order to have no errors when initdb create the database, default value was not set and initdb stop). I create an user and a test database, with no problem. In order to testing, i have a batch with a loop to alter table and add many columns... my batch stops at 1600 columns wtih this error : ERROR: tables can have at most 1600 columns I don't understand why, it's seems me all is ok, did you have an idea ? Can i have more than 1600 columns ? According to the documentation, default limit with blocksize 8kb are 250 to 1600, but with a blocksize to 32Kk limits are quadrupled, it's right ? Thanks in advance, Yannick Platform : Linux debian 64b pg_controldata output : pg_control version number: 903 Catalog version number: 201105231 Database system identifier: 5701891827790346600 Database cluster state: shut down pg_control last modified: Thu 26 Jan 2012 11:52:25 AM CET Latest checkpoint location: 0/188EA08 Prior checkpoint location: 0/188E730 Latest checkpoint's REDO location: 0/188EA08 Latest checkpoint's TimeLineID: 1 Latest checkpoint's NextXID: 0/678 Latest checkpoint's NextOID: 11868 Latest checkpoint's NextMultiXactId: 1 Latest checkpoint's NextMultiOffset: 0 Latest checkpoint's oldestXID: 668 Latest checkpoint's oldestXID's DB: 1 Latest checkpoint's oldestActiveXID: 0 Time of latest checkpoint: Thu 26 Jan 2012 11:52:25 AM CET Minimum recovery ending location: 0/0 Backup start location: 0/0 Current wal_level setting: minimal Current max_connections setting: 50 Current max_prepared_xacts setting: 0 Current max_locks_per_xact setting: 64 Maximum data alignment: 8 Database block size: 32768 Blocks per segment of large relation: 32768 WAL block size: 8192 Bytes per WAL segment: 16777216 Maximum length of identifiers: 64 Maximum columns in an index: 32 Maximum size of a TOAST chunk: 8140 Date/time type storage: 64-bit integers Float4 argument passing: by value Float8 argument passing: by value -- Yannick Monclin Université de Reims Champagne Ardenne ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: extend column limit with blocksize does not work 2012-01-26 12:32 extend column limit with blocksize does not work Yannick Monclin <yannick.monclin@univ-reims.fr> @ 2012-01-26 15:39 ` Tom Lane <tgl@sss.pgh.pa.us> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2012-01-26 15:39 UTC (permalink / raw) To: Yannick Monclin <yannick.monclin@univ-reims.fr>; +Cc: pgsql-admin Yannick Monclin <yannick.monclin@univ-reims.fr> writes: > I use the query survey software "Limesurvey", when this sofware build > some complex survey, it's necessary to have more than 1600 columns in > one table. I'd suggest rethinking the database schema. Even if you could get that to work, it's likely to perform pretty horridly. > So, i have used this parameter (configure > --with-blocksize=32) to build my last postgresql (9.1.2). BLCKSZ is not the limiting factor here --- it's the tuple header format, specifically the width of t_hoff. You might care to look at the first few comments in src/include/access/htup.h. regards, tom lane ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2012-01-26 15:39 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2012-01-26 12:32 extend column limit with blocksize does not work Yannick Monclin <yannick.monclin@univ-reims.fr> 2012-01-26 15:39 ` Tom Lane <tgl@sss.pgh.pa.us>
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