Jan de Visser wrote:
Hello,
After fixing the hanging problems I reported here earlier (by uninstalling
W2K3 SP1), I'm running into another weird one.
After doing a +/- 8hr cycle of updates and inserts (what we call a 'batch'),
the first 'reporting' type query on tables involved in that write cycle is
very slow. As an example, I have a query which according to EXPLAIN ANALYZE
takes about 1.1s taking 46s. After this one hit, everything is back to
normal, and subsequent executions of the same query are in fact subsecond.
Restarting the appserver and pgsql does not make the slowness re-appear, only
running another batch will.
During the 'write'/batch cycle, a large number of rows in various tables are
inserted and subsequently (repeatedly) updated. The reporting type queries
after that are basically searches on those tables.
After a large batch you need to run 'analyze' over the tables involved
to get postgresql to update it's statistics so it can work out which
indexes etc it should use.
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