Re: Avoid overhead open-close indexes (catalog updates)

Em ter., 15 de nov. de 2022 às 04:02, Michael Paquier <michael@paquier.xyz>
escreveu:

> On Tue, Nov 15, 2022 at 09:57:26AM +0900, Michael Paquier wrote:
> > Anyway, multi-inserts are going to be solution better than
> > CatalogTupleInsertWithInfo() in some cases, because we would just
> > generate one WAL record of N inserts rather than N records with one
> > INSERT each.
>
> Something that you did not consider in the initial patch is that we
> may finish by opening catalog indexes even in cases where this would
> not have happened on HEAD, as we may finish by doing nothing when
> copying the stats or updating them during an analyze, and that's not
> fine IMO.  However it is easy enough to minimize the cost: just do a
> CatalogOpenIndexes() when absolutely required, and close things only
> if the indexes have been opened.
>
I find it very difficult not to have some tuple to be updated,
once inside CopyStatistics and the branch cost can get in the way,
but I don't object with your solution.


>
> Then, there are the cases where it is worth switching to a
> multi-insert logic as these are going to manipulate more than 2
> entries all the time: enum list addition and two code paths of
> tsearchcmds.c (where up to 16 entries can be lined up).  This is a
> case-by-case analysis.  For example, in the case of the enums, the
> number of elements is known in advance so it is possible to know the
> number of slots that would be used and initialize them.  But that's
> not something you would do for the first tsearch bits where the data
> is built upon a scan so the slot init should be delayed.  The second
> tsearch one can use a predictible approach, like the enums based on
> the number of known elements to insert.
>
Makes sense.


>
> So I've given a try at all that, and finished with the attached.  This
> patch finishes with a list of bullet points, so this had better be
> split into different commits, I guess.
> Thoughts?
>
Missed AddRoleMems?
Could you continue with CatalogTupleInsertWithInfo, what do you think?

regards,
Ranier Vilela