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--
-- EXPLAIN
--
-- There are many test cases elsewhere that use EXPLAIN as a vehicle for
-- checking something else (usually planner behavior). This file is
-- concerned with testing EXPLAIN in its own right.
--
-- To produce stable regression test output, it's usually necessary to
-- ignore details such as exact costs or row counts. These filter
-- functions replace changeable output details with fixed strings.
create function explain_filter(text) returns setof text
language plpgsql as
$$
declare
ln text;
begin
for ln in execute $1
loop
-- Replace any numeric word with just 'N'
ln := regexp_replace(ln, '\m\d+\M', 'N', 'g');
-- In sort output, the above won't match units-suffixed numbers
ln := regexp_replace(ln, '\m\d+kB', 'NkB', 'g');
-- Ignore text-mode buffers output because it varies depending
-- on the system state
CONTINUE WHEN (ln ~ ' +Buffers: .*');
-- Ignore text-mode "Planning:" line because whether it's output
-- varies depending on the system state
CONTINUE WHEN (ln = 'Planning:');
return next ln;
end loop;
end;
$$;
-- To produce valid JSON output, replace numbers with "0" or "0.0" not "N"
create function explain_filter_to_json(text) returns jsonb
language plpgsql as
$$
declare
data text := '';
ln text;
begin
for ln in execute $1
loop
-- Replace any numeric word with just '0'
ln := regexp_replace(ln, '\m\d+\M', '0', 'g');
data := data || ln;
end loop;
return data::jsonb;
end;
$$;
-- Simple cases
select explain_filter('explain select * from int8_tbl i8');
select explain_filter('explain (analyze) select * from int8_tbl i8');
select explain_filter('explain (analyze, verbose) select * from int8_tbl i8');
select explain_filter('explain (analyze, buffers, format text) select * from int8_tbl i8');
select explain_filter('explain (analyze, buffers, format json) select * from int8_tbl i8');
select explain_filter('explain (analyze, buffers, format xml) select * from int8_tbl i8');
select explain_filter('explain (analyze, buffers, format yaml) select * from int8_tbl i8');
select explain_filter('explain (buffers, format text) select * from int8_tbl i8');
select explain_filter('explain (buffers, format json) select * from int8_tbl i8');
-- SETTINGS option
-- We have to ignore other settings that might be imposed by the environment,
-- so printing the whole Settings field unfortunately won't do.
begin;
set local plan_cache_mode = force_generic_plan;
select true as "OK"
from explain_filter('explain (settings) select * from int8_tbl i8') ln
where ln ~ '^ *Settings: .*plan_cache_mode = ''force_generic_plan''';
select explain_filter_to_json('explain (settings, format json) select * from int8_tbl i8') #> '{0,Settings,plan_cache_mode}';
rollback;
--
-- Test production of per-worker data
--
-- Unfortunately, because we don't know how many worker processes we'll
-- actually get (maybe none at all), we can't examine the "Workers" output
-- in any detail. We can check that it parses correctly as JSON, and then
-- remove it from the displayed results.
-- Serializable isolation would disable parallel query, so explicitly use an
-- arbitrary other level.
begin isolation level repeatable read;
-- encourage use of parallel plans
set parallel_setup_cost=0;
set parallel_tuple_cost=0;
set min_parallel_table_scan_size=0;
set max_parallel_workers_per_gather=4;
select jsonb_pretty(
explain_filter_to_json('explain (analyze, verbose, buffers, format json)
select * from tenk1 order by tenthous')
-- remove "Workers" node of the Seq Scan plan node
#- '{0,Plan,Plans,0,Plans,0,Workers}'
-- remove "Workers" node of the Sort plan node
#- '{0,Plan,Plans,0,Workers}'
-- Also remove its sort-type fields, as those aren't 100% stable
#- '{0,Plan,Plans,0,Sort Method}'
#- '{0,Plan,Plans,0,Sort Space Type}'
);
rollback;
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