Hannu Krosing wrote:
Did it fit in shared_buffers, or system cache ?
Database was ~5GB, server has 16GB, shared buffers was set to 1920MB.
I first noticed this several years ago, when doing a COPY to a large
table with indexes took noticably longer (2-3 times longer) when the
indexes were in system cache than when they were in shared_buffers.
I read this as a hint: try increasing shared_buffers. I'll redo the
pgbench run with increased shared_buffers.
so the test is actually how fast the ssd can capture
sequential WAL writes and fsync without barriers, mixed with an
occasional checkpoint with random write IO on another partition). Since
the WAL writing is the same for both block_size setups, I decided to
compare random writes to a file of 5GB with Oracle's Orion tool:
Are you sure that you are not writing full WAL pages ?
I'm not sure I understand this question.
Do you have any stats on how much WAL is written for 8kb and 4kb test
cases ?
Would some iostat -xk 1 for each partition suffice?
And for other disk i/o during the tests ?
Not existent.
regards,
Yeb Havinga
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