On 4/14/14, 4:50 PM, Andres Freund wrote:

On 2014-04-14 14:33:03 -0700, Joe Conway wrote:
checkpoint_segments = 96
checkpoint_timeout = 10min

I realize there are many things that can be done to improve my
specific scenario, e.g. drop indexes before loading, change various
configs, etc. My purpose for this post is to ask if it is really
expected to get over 20 times as much WAL as heap data?

I'd bet a large percentage of this will be full page images of the
index. The values you index are essentially distributed over the whole
index, so you'll modifiy the same indx values repeatedly. But often
enough it won't be in the same checkpoint and thus will create full page

My thought exactly...

ISTM that we should be able to push all the index inserts to the end of the 
transaction. That should greatly reduce the amount of full page writes. That 
would also open the door for doing all the index inserts in parallel.
Jim C. Nasby, Data Architect                       j...@nasby.net
512.569.9461 (cell)                         http://jim.nasby.net

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