* Robert Haas (robertmh...@gmail.com) wrote: > I dunno what a typical checkpoint size is but I don't think you'll be > exaggerating much if you imagine that everything that could possibly > be dirty is.
This is not uncommon for us, at least: checkpoint complete: wrote 425844 buffers (20.3%); 0 transaction log file(s) added, 0 removed, 249 recycled; write=175.535 s, sync=17.428 s, total=196.357 s; sync files=1011, longest=2.675 s, average=0.017 s That's a checkpoint writing out 20% of 16GB, or over 3GB, and that's just from one of the four postmasters running- we get this kind of checkpointing happening on all of them. All told, it's easy for us to want to write over 12GB during a single checkpoint period on this box. (checkpoint_timeout is 5m, checkpoint_target is 0.9). Thankfully, the box has 256G of RAM and so the shared buffers only use up 25% of the RAM in the box. :) I'm sure others could post larger numbers. Thanks, Stephen
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