Hi,
Another "funny" thing: I have a query which runs
on (Linux) PostgreSQL 7.4.x under 10 sec. I tried
to run it on (Windows) PostgreSQL 8.0 yesterday.
It didn't finished at all! (I shoot it down after 10 minutes)
I made various tests and I figured out something interesting:
The same query with:
A, "history.undo_action_id > 0" runs in 10 sec.
B, "history.undo_action_id is not null" runs in 10 sec.
C, "history.undo_action_id is null" runs forever (?!)
I used EXPLAIN but I couldn't figure out what the problem was.
In every explain output are 3 lines:
" -> Index Scan using speed_3 on history (.........)"
" Index Cond: (type_id = 6)"
" Filter: (undo_action_id IS NOT NULL)"
where "speed_3" is a btree index on history.type_id. There is also an index
for history.undo_action_id (btree) but it is not used.
The tables are well indexed, and have about 200.000 records.
The SQL file and the 3 scenarios are in attachment.
Help, anyone?
Vig Sándor
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