Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Tom, let me know what caches you want on pg_statistics, or if you would
> prefer to do it yourself, instructions are at the top of syscache.c.
AFAIK the only index we need is one on starelid + staattnum. If you
have the time, please put it in and teach getattstatistics() in
backend/utils/adt/selfuncs.c to use it. That seems to be the only
place that reads pg_statistic.
If you wanted to include staop as a third column, then the index could
be UNIQUE. (We don't actually use staop at the moment, but I think it
should be left in place for possible future use.)
vacuum.c may also need to be taught to fill the index...
regards, tom lane