Обсуждение: pgsql: Implement lazy XID allocation: transactions that do not modify
pgsql: Implement lazy XID allocation: transactions that do not modify
От
tgl@postgresql.org (Tom Lane)
Дата:
Log Message: ----------- Implement lazy XID allocation: transactions that do not modify any database rows will normally never obtain an XID at all. We already did things this way for subtransactions, but this patch extends the concept to top-level transactions. In applications where there are lots of short read-only transactions, this should improve performance noticeably; not so much from removal of the actual XID-assignments, as from reduction of overhead that's driven by the rate of XID consumption. We add a concept of a "virtual transaction ID" so that active transactions can be uniquely identified even if they don't have a regular XID. This is a much lighter-weight concept: uniqueness of VXIDs is only guaranteed over the short term, and no on-disk record is made about them. Florian Pflug, with some editorialization by Tom. Modified Files: -------------- pgsql/doc/src/sgml: catalogs.sgml (r2.156 -> r2.157) (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/catalogs.sgml?r1=2.156&r2=2.157) config.sgml (r1.141 -> r1.142) (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.141&r2=1.142) pgsql/src/backend/access/heap: heapam.c (r1.237 -> r1.238) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/heap/heapam.c?r1=1.237&r2=1.238) pgsql/src/backend/access/transam: README (r1.6 -> r1.7) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/README?r1=1.6&r2=1.7) clog.c (r1.43 -> r1.44) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/clog.c?r1=1.43&r2=1.44) multixact.c (r1.24 -> r1.25) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/multixact.c?r1=1.24&r2=1.25) twophase.c (r1.32 -> r1.33) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/twophase.c?r1=1.32&r2=1.33) xact.c (r1.247 -> r1.248) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c?r1=1.247&r2=1.248) xlog.c (r1.279 -> r1.280) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.279&r2=1.280) pgsql/src/backend/catalog: system_views.sql (r1.41 -> r1.42) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/system_views.sql?r1=1.41&r2=1.42) pgsql/src/backend/commands: indexcmds.c (r1.162 -> r1.163) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/indexcmds.c?r1=1.162&r2=1.163) sequence.c (r1.143 -> r1.144) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/sequence.c?r1=1.143&r2=1.144) vacuum.c (r1.355 -> r1.356) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuum.c?r1=1.355&r2=1.356) vacuumlazy.c (r1.90 -> r1.91) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuumlazy.c?r1=1.90&r2=1.91) pgsql/src/backend/storage/ipc: procarray.c (r1.28 -> r1.29) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/procarray.c?r1=1.28&r2=1.29) sinvaladt.c (r1.63 -> r1.64) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/sinvaladt.c?r1=1.63&r2=1.64) pgsql/src/backend/storage/lmgr: lmgr.c (r1.92 -> r1.93) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lmgr.c?r1=1.92&r2=1.93) lock.c (r1.177 -> r1.178) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lock.c?r1=1.177&r2=1.178) proc.c (r1.192 -> r1.193) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/proc.c?r1=1.192&r2=1.193) pgsql/src/backend/storage/smgr: smgr.c (r1.105 -> r1.106) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/smgr/smgr.c?r1=1.105&r2=1.106) pgsql/src/backend/utils/adt: lockfuncs.c (r1.28 -> r1.29) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/lockfuncs.c?r1=1.28&r2=1.29) pgsql/src/backend/utils/error: elog.c (r1.195 -> r1.196) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/error/elog.c?r1=1.195&r2=1.196) pgsql/src/backend/utils/misc: postgresql.conf.sample (r1.225 -> r1.226) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/postgresql.conf.sample?r1=1.225&r2=1.226) pgsql/src/include/access: xact.h (r1.88 -> r1.89) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/xact.h?r1=1.88&r2=1.89) xlog.h (r1.82 -> r1.83) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/xlog.h?r1=1.82&r2=1.83) pgsql/src/include: c.h (r1.220 -> r1.221) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/c.h?r1=1.220&r2=1.221) pgsql/src/include/catalog: catversion.h (r1.422 -> r1.423) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.422&r2=1.423) pgsql/src/include/storage: lmgr.h (r1.58 -> r1.59) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/lmgr.h?r1=1.58&r2=1.59) lock.h (r1.106 -> r1.107) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/lock.h?r1=1.106&r2=1.107) proc.h (r1.99 -> r1.100) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/proc.h?r1=1.99&r2=1.100) procarray.h (r1.14 -> r1.15) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/procarray.h?r1=1.14&r2=1.15) sinvaladt.h (r1.42 -> r1.43) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/sinvaladt.h?r1=1.42&r2=1.43) smgr.h (r1.58 -> r1.59) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/smgr.h?r1=1.58&r2=1.59) pgsql/src/test/regress/expected: rules.out (r1.131 -> r1.132) (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/rules.out?r1=1.131&r2=1.132)
On 9/5/2007 2:10 PM, Tom Lane wrote: > Log Message: > ----------- > Implement lazy XID allocation: transactions that do not modify any database > rows will normally never obtain an XID at all. We already did things this way As a side note, this patch is transparent enough that it doesn't seem to affect even Slony replication, which makes excessive use of transaction ID's and snapshot information to decide which log rows to apply together in order to guarantee consistency on subscribers at all times. Good Job! Jan > for subtransactions, but this patch extends the concept to top-level > transactions. In applications where there are lots of short read-only > transactions, this should improve performance noticeably; not so much from > removal of the actual XID-assignments, as from reduction of overhead that's > driven by the rate of XID consumption. We add a concept of a "virtual > transaction ID" so that active transactions can be uniquely identified even > if they don't have a regular XID. This is a much lighter-weight concept: > uniqueness of VXIDs is only guaranteed over the short term, and no on-disk > record is made about them. > > Florian Pflug, with some editorialization by Tom. > > Modified Files: > -------------- > pgsql/doc/src/sgml: > catalogs.sgml (r2.156 -> r2.157) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/catalogs.sgml?r1=2.156&r2=2.157) > config.sgml (r1.141 -> r1.142) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.141&r2=1.142) > pgsql/src/backend/access/heap: > heapam.c (r1.237 -> r1.238) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/heap/heapam.c?r1=1.237&r2=1.238) > pgsql/src/backend/access/transam: > README (r1.6 -> r1.7) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/README?r1=1.6&r2=1.7) > clog.c (r1.43 -> r1.44) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/clog.c?r1=1.43&r2=1.44) > multixact.c (r1.24 -> r1.25) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/multixact.c?r1=1.24&r2=1.25) > twophase.c (r1.32 -> r1.33) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/twophase.c?r1=1.32&r2=1.33) > xact.c (r1.247 -> r1.248) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c?r1=1.247&r2=1.248) > xlog.c (r1.279 -> r1.280) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.279&r2=1.280) > pgsql/src/backend/catalog: > system_views.sql (r1.41 -> r1.42) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/system_views.sql?r1=1.41&r2=1.42) > pgsql/src/backend/commands: > indexcmds.c (r1.162 -> r1.163) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/indexcmds.c?r1=1.162&r2=1.163) > sequence.c (r1.143 -> r1.144) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/sequence.c?r1=1.143&r2=1.144) > vacuum.c (r1.355 -> r1.356) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuum.c?r1=1.355&r2=1.356) > vacuumlazy.c (r1.90 -> r1.91) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuumlazy.c?r1=1.90&r2=1.91) > pgsql/src/backend/storage/ipc: > procarray.c (r1.28 -> r1.29) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/procarray.c?r1=1.28&r2=1.29) > sinvaladt.c (r1.63 -> r1.64) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/sinvaladt.c?r1=1.63&r2=1.64) > pgsql/src/backend/storage/lmgr: > lmgr.c (r1.92 -> r1.93) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lmgr.c?r1=1.92&r2=1.93) > lock.c (r1.177 -> r1.178) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lock.c?r1=1.177&r2=1.178) > proc.c (r1.192 -> r1.193) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/proc.c?r1=1.192&r2=1.193) > pgsql/src/backend/storage/smgr: > smgr.c (r1.105 -> r1.106) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/smgr/smgr.c?r1=1.105&r2=1.106) > pgsql/src/backend/utils/adt: > lockfuncs.c (r1.28 -> r1.29) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/lockfuncs.c?r1=1.28&r2=1.29) > pgsql/src/backend/utils/error: > elog.c (r1.195 -> r1.196) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/error/elog.c?r1=1.195&r2=1.196) > pgsql/src/backend/utils/misc: > postgresql.conf.sample (r1.225 -> r1.226) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/postgresql.conf.sample?r1=1.225&r2=1.226) > pgsql/src/include/access: > xact.h (r1.88 -> r1.89) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/xact.h?r1=1.88&r2=1.89) > xlog.h (r1.82 -> r1.83) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/xlog.h?r1=1.82&r2=1.83) > pgsql/src/include: > c.h (r1.220 -> r1.221) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/c.h?r1=1.220&r2=1.221) > pgsql/src/include/catalog: > catversion.h (r1.422 -> r1.423) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.422&r2=1.423) > pgsql/src/include/storage: > lmgr.h (r1.58 -> r1.59) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/lmgr.h?r1=1.58&r2=1.59) > lock.h (r1.106 -> r1.107) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/lock.h?r1=1.106&r2=1.107) > proc.h (r1.99 -> r1.100) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/proc.h?r1=1.99&r2=1.100) > procarray.h (r1.14 -> r1.15) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/procarray.h?r1=1.14&r2=1.15) > sinvaladt.h (r1.42 -> r1.43) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/sinvaladt.h?r1=1.42&r2=1.43) > smgr.h (r1.58 -> r1.59) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/smgr.h?r1=1.58&r2=1.59) > pgsql/src/test/regress/expected: > rules.out (r1.131 -> r1.132) > (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/rules.out?r1=1.131&r2=1.132) > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck@Yahoo.com #