Greg Stark escribió:
> There is another use case which perhaps needs to be addressed: if the
> user has some queries which are very latency sensitive and others
> which are not latency sensitive. In that case it might be very
> important to keep the pages of data used by the high priority queries
> in the cache. That's something we should have a high level abstract
> interface for, not depend on low level system features.
Yeah.
I wonder if the right thing for this is to mark the objects (pages), or
the queries, as needing special attention. If you mark the queries,
then perhaps they could behave slightly differently like adding +2 or so
to buffer usage count instead of +1, so that they take longer than a
normal buffer in getting evicted. This way you don't force the admin to
figure out what's the right size ratio for different named caches, etc.
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Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.