Dnia 2003-12-22 11:39, Użytkownik Ryszard Lach napisał:

Hi.

I have a table with 24k records and btree index on column 'id'. Is this
normal, that 'select max(id)' or 'select count(id)' causes a sequential
scan? It takes over 24 seconds (on a pretty fast machine):

'select count(id)'
Yes, this is normal. Because of MVCC all rows must be checked and Postgres doesn't cache count(*) like Mysql.


'select max(id)'
This is also normal, but try to change this query into:
select id from some_table order by id desc limit 1;

What is your Postgresql version?

Regards,
Tomasz Myrta


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