On 7/9/2004 10:16 AM, Merlin Moncure wrote:
What is it about the buffer cache that makes it so unhappy being abletohold everything? I don't want to be seen as a cache hit fascist, butisn'tit just better if the data is just *there*, available in thepostmaster'sto doaddress space ready for each backend process to access it, rather than expecting the Linux cache mechanism, optimised as it may be, to havethe caching?
The disk cache on most operating systems is optimized. Plus, keeping shared buffers low gives you more room to bump up the sort memory, which will make your big queries run faster.
Plus, the situation will change dramatically with 7.5 where the disk cache will have less information than the PG shared buffers, which will become sequential scan resistant and will know that a block was pulled in on behalf of vacuum and not because the regular database access pattern required it.
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