Michael Glaesemann wrote:


On Jun 26, 2007, at 13:49 , Heikki Linnakangas wrote:

Maximum is 0.9, to leave some headroom for fsync and any other things that need to happen during a checkpoint.

I think it might be more user-friendly to make the maximum 1 (meaning as much smoothing as you could possibly get) and internally reserve a certain amount off for whatever headroom might be required. It's more common for users to see a value range from 0 to 1 rather than 0 to 0.9.

It would then be counter-intuitive if you set it to 1.0, and see that your checkpoints consistently take 90% of the checkpoint interval.

We could just allow any value up to 1.0, and note in the docs that you should leave some headroom, unless you don't mind starting the next checkpoint a bit late. That actually sounds pretty good.

--
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com

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