On Tuesday 17 July 2007 17:52:11 you wrote: > mljv@xxxxxxxxxxxx wrote: > > I use int8 types in most PK or FK columns in a pg 8.1 database. > > > > Would int4 instead of int8 speed up creation of an index? > > Almost certainly, but by how much will depend on your hardware and size > of index. > > > int4 will reduze the size of the table, of course. Would this reduce size > > of index, too? By the same amount? > > By four bytes per entry. That's not to say you'll halve the size of your > index - obviously there's overhead for each row. > > > How much speed up will i gain on queries? Postgresql Doc mentions a > > speed-up. Is it more like 0,1%, 1% or 10% speed-up? > > Depends. If your index didn't fit in cache before and does now, the > difference can be startling. > > Here's the question to ask yourself: which columns need a 32-bit > identifier, and which need a 64-bit one? Unless you're planning a > *really* big application, user_id can probably be an int4. thank you very much for your very detailed and helpful answer. int4 is ok for almost all use cases for a long time. As my hardware budget is small, i use small boxes with only 4 GB Ram so if i can reduce the size of database more data fits in ram. so i will take this aproach and use int4 kind regards Janning
