sql: Define more columns in pg_catalog.pg_statistic_ext

[e-mbrown]

Epic: CRDB-23454
Fixes: #88108
Fixes: #93430

This commit makes sure the stxnamespace, stxkind and stxstattarget columns are defined in pg_statistics_ext.

Release note: The stxnamespace, stxkind and
stxstattarget columns are now defined in
pg_statistics_ext. Also pg_statistics_ext
no longer crashes when stxname is null.

[cockroach-teamcity]

This change is 

[knz]

pls also take a review from @rafiss

Reviewed 2 of 2 files at r1.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @e-mbrown)

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-- commits line 7 at r1:
looks to me like a bug fix worthy of a release note.

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pkg/sql/pg_catalog.go line 3465 at r1 (raw file):

		for _, row := range rows {
			tableID := tree.MustBeDInt(row[0])
			name := tree.MustBeDString(row[1])

Using MustBeDString for the name forces a heap allocation when you convert it back to a Datum below.
You could simply refer to row[1] in the addRow call below instead.

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pkg/sql/pg_catalog.go line 3488 at r1 (raw file):

				schemaOid(statSchema),        // stxnamespace
				tree.DNull,                   // stxowner
				tree.NewDInt(-1),             // stxstattarget

You can allocate this DInt just once out of the loop.

[e-mbrown]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @knz and @rafiss)

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-- commits line 7 at r1:

Previously, knz (Raphael 'kena' Poss) wrote…

looks to me like a bug fix worthy of a release note.

Done.

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pkg/sql/pg_catalog.go line 3465 at r1 (raw file):

Previously, knz (Raphael 'kena' Poss) wrote…

Using MustBeDString for the name forces a heap allocation when you convert it back to a Datum below.
You could simply refer to row[1] in the addRow call below instead.

Done.

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pkg/sql/pg_catalog.go line 3488 at r1 (raw file):

Previously, knz (Raphael 'kena' Poss) wrote…

You can allocate this DInt just once out of the loop.

Done.

[rafiss]

lgtm, with one nit!

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @e-mbrown and @knz)

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pkg/sql/pg_catalog.go line 3453 at r2 (raw file):

	schema: vtable.PgCatalogStatisticExt,
	populate: func(ctx context.Context, p *planner, db catalog.DatabaseDescriptor, addRow func(...tree.Datum) error) error {
		query := `SELECT "tableID", name, "columnIDs", "statisticID", '{d}'::CHAR[] FROM system.table_statistics;`

nit: the {d} value should be cast to "char"[]

also, can you add a comment explaining what d means here (based on the PG docs)

[jordanlewis]

Hey @e-mbrown, coincidentally (unrelated to this PR!) I noticed this issue: #93430. Would you mind adding a fix for it while you're editing pg_statistic_ext?

Thanks!

[rafiss]

nice fix! i'm adding a backport label as well

Reviewed 1 of 2 files at r3, 1 of 1 files at r4, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @e-mbrown and @knz)

[e-mbrown]

bors r=rafiss

[craig]

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[craig]

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[craig]

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