Rob Schall wrote:
Question for anyone...
I have to queries. One runs in about 2 seconds. The other takes upwards
of 2 minutes. I have a temp table that is created with 2 columns. This
table is joined with the larger database of call detail records.
However, these 2 queries are handled very differently.
1. They're different queries - the second is expecting 10 times as many
rows as the first.
2. Can't tell if that is accurate - you need to supply EXPLAIN ANALYSE
output instead of EXPLAIN, so we can see what actually happened.
calldetail=> EXPLAIN SELECT current.* FROM current JOIN anitmp ON
current.destnum=anitmp.ani AND istf=true;
QUERY PLAN
--------------------------------------------------------------------------------------
Nested Loop (cost=0.00..2026113.09 rows=500908 width=108)
calldetail=> EXPLAIN SELECT current.* FROM current JOIN anitmp ON
current.orignum=anitmp.ani AND istf=false;
---------------------------------------------------------------------------
Hash Join (cost=35.99..3402035.53 rows=5381529 width=108)
--
Richard Huxton
Archonet Ltd
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TIP 6: explain analyze is your friend
