> > I can find very little information on hot updates but I found this: > http://archives.postgresql.org/pgsql-patches/2006-11/msg00059.php > > > > It states, "This design optimizies the updates when none of the index > columns are modified and length of the tuple remains the same after > update." > > > > How can a row's length change? I think it must mean the size (in bytes) > of the row remains the same. > > > > I bet you are looking at an old design. That has undergone many > changes and the current implementation does not have any restriction > about the row length changes. But a necessary condition is to have > enough free space in the block (and of course not changing any index > columns). > > You can find the latest README in the source code under > src/backend/access/heap/README.HOT > I'm using 8.3.1 on Solaris and I just tried this: CREATE TABLE test (a int) WITH (hot_update='true'); It fails with: ERROR: unrecognized parameter "hot_update" Is a hot update automatic in 8.3.x and that is why there isn't any formal documentation other than what is in the source code? Jon
