On 10/04/2016 10:49 AM, Dean Rasheed wrote:
On 30 September 2016 at 12:10, Heikki Linnakangas <hlinn...@iki.fi> wrote:
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 think it's OK. The functional dependency is a single statistic, but
MCV lists and histograms are multiple statistics (multiple facts about
the data sampled), so in general when you create one of these new
objects, you are creating multiple statistics about the data.
Ok. I don't really have any better ideas, was just hoping that someone
Also I find "CREATE STATISTIC" just sounds a bit clumsy compared to
The convention for naming system catalogs seems to be to use the
singular for tables and plural for views, so I guess we should stick
However, for tables and views, each object you store in those views is a
"table" or "view", but with this thing, the object you store is
"statistics". Would you have a catalog table called "pg_scissor"?
We call the current system table "pg_statistic", though. I agree we
should call it pg_mv_statistic, in singular, to follow the example of
Of course, the user-friendly system view on top of that is called
"pg_stats", just to confuse things more :-).
It doesn't seem like the end of the world that it doesn't
match the user-facing syntax. A bigger concern is the use of "mv" in
the name, because as has already been pointed out, this table may also
in the future be used to store univariate expression and partial
statistics, so I think we should drop the "mv" and go with something
like pg_statistic_ext, or some other more general name.
Also, "mv" makes me think of materialized views, which is completely
unrelated to this.
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