Hi Aaron, > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of > Aaron Werman > Sent: vrijdag 2 april 2004 13:57 > > > another thing that I have all over the place is a hierarchy: > index on grandfather_table(grandfather) > index on father_table(grandfather, father) > index on son_table(grandfather, father, son) >
It depends on your data-distribution, but I find that in almost all cases it's beneficial to have your indexes the other way round in such cases: index on grandfather_table(grandfather) index on father_table(father, grandfather) index on son_table(son, father, grandfather) That usually gives a less common, more selective value at the start of the index, making the initial selection in the index smaller. And AFAIK I don't have to rewrite my queries for that; the planner doesn't care about the order of expressions in the query that are on the same level. That said, I tend to use 'surrogate keys'; keys generated from sequences or auto-number columns for my tables. It makes the tables less readable, but the indexes remain smaller. Greetings, --Tim ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
