> I work at a project related to a possibility to have the index
> statistics auto-updated and humbly I ask your opinion.

m. Th.,

Just a thought, but a pie chart doesn't really tell you much. Everyone
who doesn't understand 100% of the issues is going to click somewhere
between indifferent and very useful.

My (limited) understanding is as follows:

The job of the optimiser is to analyse the query and determine the
least cost method of solving it, making use of any available index.
The usefulness of an index or a combination of indices is determined
by their true selectivity. The statistics tell the optimiser about the
selectivity of the index.

As new records are inserted, and old records are updated and deleted,
the true selectivity of an index may change. Consider an indexed field
with unique values (although not enforced by constraint). If I ran the
query 'update table set field=1;', the true selectivity of the index
would (after garbage collection etc) be poor, but the statistics
provided to the optimiser would indicate it was a good one to use.

Yet there are people selecting that they are against the feature. I
would like to know their reasons? Performance concerns? Something else?

Adam