26.07.10 12:15, Craig Ringer написав(ла):
On 26/07/10 16:35, Piotr Gasidło wrote:
Hello,
I've found strange problem in my database (8.4.4, but also 9.0beta3,
default postgresql.conf, shared_buffers raised to 256MB).
EXPLAIN ANALYZE SELECT ...
Total runtime: 4.782 ms
Time: 25,970 ms
SELECT ...
...
(21 rows)
Time: 23,042 ms
Test done in psql connected by socket to server (same host, using
\timing to get runtime).
Does big difference in "Total runtime" and "Time" is normal?
Given that EXPLAIN ANALYZE doesn't transfer large rowsets to the client,
it can't really be time taken to transfer the data, which is the usual
difference between 'explain analyze' timings and psql client-side timings.
Given that, I'm wondering if the difference in this case is planning
time. I can't really imagine the query planner taking 20 seconds (!!) to
run, though, no matter how horrifyingly complicated the query and table
structure were, unless there was something going wrong.
Actually it's 20ms, so I suspect your point about planning time is correct.
Piotr: You can try preparing your statement and then analyzing execute
time to check if this is planning time.
Best regards, Vitalii Tymchyshyn
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