In-memory indexes for pg_class

[zachmu]

See dolthub/go-mysql-server#3190

This is a proof of concept for pg_class. Other pg_catalog tables are next.

[github-actions]

	Main	PR
covering_index_scan_postgres	328.10/s	344.37/s	+4.9%
index_join_postgres	152.54/s	154.12/s	+1.0%
index_join_scan_postgres	194.46/s	192.40/s	-1.1%
index_scan_postgres	12.31/s	12.34/s	+0.2%
oltp_point_select	2513.69/s	2493.15/s	-0.9%
oltp_read_only	1816.71/s	1787.21/s	-1.7%
select_random_points	117.50/s	118.81/s	+1.1%
select_random_ranges	129.83/s	132.11/s	+1.7%
table_scan_postgres	11.61/s	11.58/s	-0.3%
types_table_scan_postgres	5.38/s	5.44/s	+1.1%

[Hydrocharged]

LGTM! No real comments on the content, really just nitpicking

[github-actions]

	Main	PR
Total	42090	42090
Successful	16828	16832
Failures	25262	25258
Partial Successes1	5552	5553

	Main	PR
Successful	39.9810%	39.9905%
Failures	60.0190%	60.0095%

${\color{red}Regressions (1)}$

rules

QUERY:          update t1 set a = 4 where a = 5;
RECEIVED ERROR: duplicate primary key given: [4] (errno 1062) (sqlstate HY000)

${\color{lightgreen}Progressions (5)}$

indexing

QUERY: select relhassubclass from pg_class where relname = 'idxpart_idx';

QUERY: select relhassubclass from pg_class where relname = 'idxpart_idx';

join

QUERY: select * from
  zt2 left join zt3 on (f2 = f3)
      left join zt1 on (f3 = f1)
where f2 = 53;

QUERY: select * from int4_tbl a full join int4_tbl b on true;

select_having

QUERY: SELECT a FROM test_having HAVING min(a) < max(a);

Footnotes

1. These are tests that we're marking as Successful, however they do not match the expected output in some way. This is due to small differences, such as different wording on the error messages, or the column names being incorrect while the data itself is correct. ↩