Re: multivariate statistics (v19)

On Fri, Sep 30, 2016 at 8:10 PM, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
> This patch set is in pretty good shape, the only problem is that it's so big
> that no-one seems to have the time or courage to do the final touches and
> commit it.

Did you see my suggestions about simplifying its SQL structure? You
could shave some code without impacting the base set of features.

> I fear that using "statistics" as the name of the new object might get a bit
> awkward. "statistics" is a plural, but we use it as the name of a single
> object, like "pants" or "scissors". Not sure I have any better ideas though.
> "estimator"? "statistics collection"? Or perhaps it should be singular,
> "statistic". I note that you actually called the system table
> "pg_mv_statistic", in singular.
>
> I'm not a big fan of storing the stats as just a bytea blob, and having to
> use special functions to interpret it. By looking at the patch, it's not
> clear to me what we actually store for functional dependencies. A list of
> attribute numbers? Could we store them simply as an int[]? (I'm not a big
> fan of the hack in pg_statistic, that allows storing arrays of any data type
> in the same column, though. But for functional dependencies, I don't think
> we need that.)

I am marking this patch as returned with feedback for now.

> Overall, this is going to be a great feature!

+1.
--
Michael