no need #include "nodes/pg_list.h" since src/include/statistics/statistics.h sub level include "nodes/pg_list.h"
no need #include "utils/palloc.h" sicne #include "postgres.h" already included it.
Noted.
select '[{"6, -32768,,": -11}]'::pg_ndistinct; ERROR: malformed pg_ndistinct: "[{"6, -32768,,": -11}]" LINE 1: select '[{"6, -32768,,": -11}]'::pg_ndistinct; ^ DETAIL: All ndistinct count values are scalar doubles. imho, this errdetail message is not good.
What error message do you think is appropriate in that situation?
select '{}'::pg_ndistinct ; segfault
Mmm, gotta look into that!
select '{"1,":"1"}'::pg_ndistinct ; ERROR: malformed pg_ndistinct: "{"1,":"1"}" LINE 1: select '{"1,":"1"}'::pg_ndistinct ; ^ DETAIL: All ndistinct attnum lists must be a comma separated list of attnums.
imho, this errdetail message is not good. would be better saying that "length of list of attnums must be larger than 1".
That sounds better.
typcategory (Z) marked as Internal-use types. and there is no pg_ndistinct array type, not sure this is fine.
I think it's probably ok for now. The datatype currently has no utility other than extended statistics, and I'm doubtful that it ever will.
