On Thu, 2007-05-03 at 22:32 +0200, Alexander Staubo wrote: > On 5/3/07, Matthew Hixson <hixson@xxxxxxxxxxxxxxxx> wrote: > > Is there a significant performance difference between using int > > primary keys and string primary keys in Postgres? > > PostgreSQL uses B-trees for its indexes, insertion time is logarithmic > regardless of the type of the key, but strings have a larger overhead > since they involve character comparisons; (i - j) is a lot faster than > strcmp(i, j). If you do go for strings, I would suggest that the If you're using a non-C locale, it's slower than strcmp() too. PostgreSQL has to do an extra memcpy() in order to use strcoll(), because strings in postgresql aren't necessarily NULL-terminated and there's no such thing as strncoll(), unfortunately (a comment in the code points this out). This mostly matters in sorting. If your B-tree is in memory and you do a simple lookup (what else would you do with UUIDs?), it's unlikely to take very long at all. Regards, Jeff Davis
