--
-- Test assorted system views
--
-- This test is mainly meant to provide some code coverage for the
-- set-returning functions that underlie certain system views.
-- The output of most of these functions is very environment-dependent,
-- so our ability to test with fixed expected output is pretty limited;
-- but even a trivial check of count(*) will exercise the normal code path
-- through the SRF.
select count(*) >= 0 as ok from pg_available_extension_versions;
 ok 
----
 t
(1 row)

select count(*) >= 0 as ok from pg_available_extensions;
 ok 
----
 t
(1 row)

-- The entire output of pg_backend_memory_contexts is not stable,
-- we test only the existence and basic condition of TopMemoryContext.
select name, ident, parent, level, total_bytes >= free_bytes
  from pg_backend_memory_contexts where level = 0;
       name       | ident | parent | level | ?column? 
------------------+-------+--------+-------+----------
 TopMemoryContext |       |        |     0 | t
(1 row)

-- At introduction, pg_config had 23 entries; it may grow
select count(*) > 20 as ok from pg_config;
 ok 
----
 t
(1 row)

-- We expect no cursors in this test; see also portals.sql
select count(*) = 0 as ok from pg_cursors;
 ok 
----
 t
(1 row)

select count(*) >= 0 as ok from pg_file_settings;
 ok 
----
 t
(1 row)

-- There will surely be at least one rule, with no errors.
select count(*) > 0 as ok, count(*) FILTER (WHERE error IS NOT NULL) = 0 AS no_err
  from pg_hba_file_rules;
 ok | no_err 
----+--------
 t  | t
(1 row)

-- There may be no rules, and there should be no errors.
select count(*) >= 0 as ok, count(*) FILTER (WHERE error IS NOT NULL) = 0 AS no_err
  from pg_ident_file_mappings;
 ok | no_err 
----+--------
 t  | t
(1 row)

-- There will surely be at least one active lock
select count(*) > 0 as ok from pg_locks;
 ok 
----
 t
(1 row)

-- We expect no prepared statements in this test; see also prepare.sql
select count(*) = 0 as ok from pg_prepared_statements;
 ok 
----
 t
(1 row)

-- See also prepared_xacts.sql
select count(*) >= 0 as ok from pg_prepared_xacts;
 ok 
----
 t
(1 row)

-- There will surely be at least one SLRU cache
select count(*) > 0 as ok from pg_stat_slru;
 ok 
----
 t
(1 row)

-- There must be only one record
select count(*) = 1 as ok from pg_stat_wal;
 ok 
----
 t
(1 row)

-- We expect no walreceiver running in this test
select count(*) = 0 as ok from pg_stat_wal_receiver;
 ok 
----
 t
(1 row)

-- This is to record the prevailing planner enable_foo settings during
-- a regression test run.
select name, setting from pg_settings where name like 'enable%';
              name              | setting 
--------------------------------+---------
 enable_async_append            | on
 enable_bitmapscan              | on
 enable_gathermerge             | on
 enable_hashagg                 | on
 enable_hashjoin                | on
 enable_incremental_sort        | on
 enable_indexonlyscan           | on
 enable_indexscan               | on
 enable_material                | on
 enable_memoize                 | on
 enable_mergejoin               | on
 enable_nestloop                | on
 enable_parallel_append         | on
 enable_parallel_hash           | on
 enable_partition_pruning       | on
 enable_partitionwise_aggregate | off
 enable_partitionwise_join      | off
 enable_seqscan                 | on
 enable_sort                    | on
 enable_tidscan                 | on
(20 rows)

-- Test that the pg_timezone_names and pg_timezone_abbrevs views are
-- more-or-less working.  We can't test their contents in any great detail
-- without the outputs changing anytime IANA updates the underlying data,
-- but it seems reasonable to expect at least one entry per major meridian.
-- (At the time of writing, the actual counts are around 38 because of
-- zones using fractional GMT offsets, so this is a pretty loose test.)
select count(distinct utc_offset) >= 24 as ok from pg_timezone_names;
 ok 
----
 t
(1 row)

select count(distinct utc_offset) >= 24 as ok from pg_timezone_abbrevs;
 ok 
----
 t
(1 row)

-- Let's check the non-default timezone abbreviation sets, too
set timezone_abbreviations = 'Australia';
select count(distinct utc_offset) >= 24 as ok from pg_timezone_abbrevs;
 ok 
----
 t
(1 row)

set timezone_abbreviations = 'India';
select count(distinct utc_offset) >= 24 as ok from pg_timezone_abbrevs;
 ok 
----
 t
(1 row)