Re: bitmap scans, btree scans, and tid order
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Jeffrey W. Baker" <jwbaker@acm.org>
Cc: pgsql-hackers@postgresql.org
Date: 2005-05-16T04:58:52Z
Lists: pgsql-hackers
"Jeffrey W. Baker" <jwbaker@acm.org> writes: > I see that Tom has already done the infrastructure work by adding > getmulti, but getmulti isn't used by nodeIndexscan.c, only > nodeBitmapIndexscan.c. Will btree index scans be executed by creating > in-memory bitmaps in 8.1, or will some scans still be executed the usual > way? We aren't going to remove the existing indexscan behavior, because bitmap scans lose the ordering of the underlying index. There are many situations where that ordering is important. (See for instance the recent changes to make MAX/MIN use that behavior.) regards, tom lane