It's been bugging me for a while now that we don't have a prewarming utility, for a couple of reasons, including:
1. Our customers look at me funny when I suggest that they use pg_relation_filepath() and /bin/dd for this purpose. 2. Sometimes when I'm benchmarking stuff, I want to get all the data cached in shared_buffers. This is surprisingly hard to do if the size of any relation involved is >=1/4 of shared buffers, because the BAS_BULKREAD stuff kicks in. You can do it by repeatedly seq-scanning the relation - eventually all the blocks trickle in - but it takes a long time, and that's annoying. So I wrote a prewarming utility. Patch is attached. You can prewarm either the OS cache or PostgreSQL's cache, and there are two options for prewarming the OS cache to meet different needs. By passing the correct arguments to the function, you can prewarm an entire relation or just the blocks you choose; prewarming of blocks from alternate relation forks is also supported, for completeness. Hope you like it. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
pg_prewarm_v1.patch
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