On 12/08/2013 08:14 PM, Greg Stark wrote:
The whole accounts table is 1.2GB and contains 10 million rows. As expected with rows_per_block set to 1 it reads 240MB of that containing nearly 2 million rows (and takes nearly 20s -- doing a full table scan for select count(*) only takes about 5s):
One simple thing we could do, without or in addition to changing the algorithm, is to issue posix_fadvise() calls for the blocks we're going to read. It should at least be possible to match the speed of a plain sequential scan that way.
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