Re: Statistics Import and Export

>
> pg_dump --dbname=src2 --table=tenk1 --statistics-only --verbose > x.sql
> there no pg_restore_attribute_stats, pg_restore_relation_stats there
> for table tenk1.
> There aren't any statistics, should there be?
>

pg_restore_relation_stats: yes. looking into that.
pg_restore_attribute_stats: yes IF the table had been analyzed, no
otherwise.

> also should
> pg_dump --dbname=src2 --no-data --no-schema --table=tenk1
> dump the statistics? currently seems no.
>

> in doc/src/sgml/ref/pg_dump.sgml
> there are six options to control the main output now.
> --schema-only, --statistics-only, --data-only,
> --no-schema, --no-data, --no-statistics
> maybe we need spare one paragraph to explain the default behavior,
> and also have an example on it?
>

+1

> pg_dump --dbname=src2 --table=tenk1 --verbose > 1.sql
> seems the statistics dump (pg_restore_attribute_stats) is ordered by
> attribute name.
> should it make more sense to order by attnum?
>

For security reasons, we pull attribute statistics from pg_stats (
https://www.postgresql.org/docs/current/view-pg-stats.html) which does not
have attnum. The only reason we order the list is to ensure that dump
comparison tests match.

> getRelationStatistics
> typedef struct _relStatsInfo
> {
> DumpableObject dobj;
> char relkind; /* 'r', 'v', 'c', etc */
> bool postponed_def;
> } RelStatsInfo;
> comment /* 'r', 'v', 'c', etc */
> Is it wrong? there is no relkind='c'.
>

Yeah, I think 'c' should be an 'm' there.

> field postponed_def really deserves a comment.
>

Can do.

>
>
> we also need change
> enum dbObjectTypePriorities
> static const int dbObjectTypePriority[]
> ?
>

We'd need two entries, because that enum includes PRIO_PRE_DATA_BOUNDARY
and PRIO_POST_DATA_BOUNDARY, and statistics can either be in DATA or
POST_DATA.

>
>
> in dumpRelationStats, we can add Assert on it.
> if (!fout->dopt->dumpStatistics)
> return;
> Assert(dobj->dump & DUMP_COMPONENT_STATISTICS);
>
>
> I found out the owner's info is missing in the dumped content.
> for example, the line "Name: STATISTICS DATA tenk1_pkey;" missing owner
> info.
> not sure this is intended?

Good question. I'm not sure if we need it or not. If stats had an owner,
it'd be the owner of the relation.