Subject Re: [firebird-support] Basic tests shows very poor performance
Author Pavel Cisar

1) Select count(*) can't use index, it does full table scan. What
performance other than pure I/O measure do you expect? Use some filter
clause. But take the 3) into account!

2) You have deleted all data, so your table s full of garbage that have
to be purged by GC. Your next table-scan query does that. Run this same
query immediately again and it should be fast as hell. But if you do a
filtered query, take the 3) into account!

3) You have changed (inserted) a lot of data. Your index statistics are
way out of date, not to mention index structure efficiency. Use ALTER
INDEX ... INACTIVE & ACTIVE to rebuild indices and recompute statistics.
It should make a difference.

best regards
Pavel Cisar