Simon Riggs wrote:
On Tue, 2007-03-20 at 14:14 +1200, Mark Kirkwood wrote:
Jeff Davis wrote:
I know we can't keep stats on every combination of columns. My initial
idea would be to only keep stats about a multi-column index (and
probably optional for those, too).

Maybe you would want to keep single column indexes too, so that (more) accurate estimates for bitmap-and type plans are possible.

We should allow the DBA to specify which groups of cols to keep
statistics on, if there is no index on that group.

That solves the combinatorial explosion problem.

This is one hint I think everyone can agree on. Being able to say that values in different columns are related just gives the planner more information to work with.

  Richard Huxton
  Archonet Ltd

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