how can i prove that the xid had been increased by 1? i do a test, step 1. SELECT datname, age(datfrozenxid) FROM pg_database; --> mydb age:33183 step 2. SELECT datname, age(datfrozenxid) FROM pg_database; --> mydb age:33188 step 3. SELECT datname, age(datfrozenxid) FROM pg_database; --> mydb age:33193 why always increased by 5? Postgresql Ver:8.1.3 using pgAdminIII Query window Andrew Sullivan wrote: > > On Wed, Dec 26, 2007 at 05:48:14PM -0800, ivan.hou wrote: >> >> XID is transcation ID? > > Yes. > >> so, "select * from mydb" is a transcation? > > Yes. > >> if i executed "select * from mydb" twice, the XID wil be increased by 2 > > Yep. Whereas if you did > > BEGIN; > SELECT 1; > SELECT 1; > COMMIT; > > the xid would be increased by 1. > > A > > ---------------------------(end of broadcast)--------------------------- > TIP 7: You can help support the PostgreSQL project by donating at > > http://www.postgresql.org/about/donate > > -- View this message in context: http://www.nabble.com/What%27s-the-XID--tp14508639p14573789.html Sent from the PostgreSQL - admin mailing list archive at Nabble.com. ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
