On 12/10/2012 04:56 PM, Xin Pan wrote:
Assumption: I have enough memory to cache all the database pages.
Goal:
Master never write pages. Slave replays logs from master and writes
pages.
Benefits:
Reduce the page IO overhead at master, save money in EC2 cloud.
I have suggested something similar on table-by-table basis but this has
not yet
generated much traction. I'll come back to this in coming weeks
For whole WAL you can achieve this by putting WAL on a large-enough
ramdrive.
Hannu
Question:
Can you give me some comments on this idea?
And I cannot turn of page writes in Postgresql.
I adjust the following parameters:
shared_buffers = 3GB
bgwriter_delay = 2000ms # 10-10000ms between rounds
bgwriter_lru_maxpages = 0 # 0-1000 max buffers
written/round
bgwriter_lru_multiplier = 0 # 0-10.0 multipler on buffers
scanned/round
checkpoint_segments = 256 # in logfile segments, min 1,
16MB each
checkpoint_timeout = 1h # range 30s-1h
checkpoint_completion_target = 1.0 # checkpoint target duration,
0.0 - 1.0
However, I still witness large amount of page writes.
Can anyone tell where are the page writes come from?
Can I turn off that part of page writes by configuration?
If not, which part of source code should I adjust to achieve my goal
(turn of page writes)?
Thanks!
Xin
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