Yann Michel wrote:

On Thu, Jun 09, 2005 at 02:11:22PM +0100, Richard Huxton wrote:

To my question: I found the parameter "stats_reset_on_server_start"
which is set to true by default. Why did you choose this (and not false)
and what are the impacts of changeing it to false? I mean, as long as I
understood it, each query or statements generates some statistic data
which is used by the optimizer (or anything equal) later on. So in my
oppinion, wouldn't it be better so set this parameter to false and to
enable a kind of a "startup reset_stats" option?

This is administrator statistics (e.g. number of disk blocks read from this index) not planner statistics. You're right - it would be foolish to throw away planner stats.

So what is best to set this parameter to and when? As I read this
parameter is documented within the section " Query and Index
Statistics Collector" so I guess it is better to set it to false as
described above. Or am I wrong?

It depends on whether you want to know how much activity your tables/indexes have received *ever* or since you last restarted. If you altered your database schema, added/removed indexes or changed hardware/configuration then you might want to reset the counts to zero to more easily see the effect of the new setup.

  Richard Huxton
  Archonet Ltd

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