"Rigmor Ukuhe" <[EMAIL PROTECTED]> writes: > query: select "NP_ID" from a WHERE "NP_ID" > '0' [is slow] > > query: select "NP_ID" from a WHERE "NP_ID" > '1' [is fast] > > There are about 37K rows and only about 100 of then are not "NP_ID" = 0
Yeah, it's scanning over all the zero values when you say "> 0" :-( This is fixed for 7.5: 2003-12-20 20:23 tgl * src/: backend/access/nbtree/nbtinsert.c, backend/access/nbtree/nbtpage.c, backend/access/nbtree/nbtsearch.c, include/access/nbtree.h: Improve btree's initial-positioning-strategy code so that we never need to step more than one entry after descending the search tree to arrive at the correct place to start the scan. This can improve the behavior substantially when there are many entries equal to the chosen boundary value. Per suggestion from Dmitry Tkach, 14-Jul-03. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend