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Re: Work Mem Allocation Questions

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In response to Brad Nicholson <bnichols@xxxxxxxxxxxxxxx>:

> 1: Is the default work_mem pre-allocated to the Postgres processes - or
> does it get allocated when needed?  Say I have work_mem at 30MB - will
> Postgres allocate that 30MB on connection, or only when it needed by a
> query?

It's allocated on demand and freed when no longer needed.

> 2: If work_mem is, say,  30MB, and my query needs 10MB - will Postgres
> allocate all 30MB, or just the 10MB I need?

Same answer.

Keep in mind that work_mem is not an upper cap, it is a per-sort limit.
Thus a query with 5 sorts could allocate 5 * work_mem.  The docs have
a little more detail on this.

-- 
Bill Moran
http://www.potentialtech.com
http://people.collaborativefusion.com/~wmoran/

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