Simon Riggs wrote:
One of the major complaints is always "Select count(*) is slow".
Although there seem to have been plenty of ideas on this they all seem
to just provide a solution for the "whole table" case. It might be that
the solution provides other benefits, but for this one case it does seem
like a lot of work.
Might it be possible to apply rule-style rewriting to a clause of an
ordinary select query? That is, is it prohibitively expensive to get PG
to recognise
SELECT count(*) FROM big_table
and replace it with
SELECT sum(summary_count) FROM my_materialised_view
This should allow you to have where-clauses and apply to a range of
cases. What I fear is that checking to see if the rule applies will cost
too much on all those queries where it doesn't apply.
--
Richard Huxton
Archonet Ltd
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