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Minor improvements in Incremental Sort explain

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Some places still used "Maximum" instead of "Peak" when displaying info
about sort space, so fix that. Also, add a comment clarifying why it's
correct to check the number of full/prefix sort groups.

Author: James Coleman
Discussion: https://postgr.es/m/CAPpHfds1waRZ=NOmueYq0sx1ZSCnt+5QJvizT8ndT2=etZEeAQ@mail.gmail.com
This commit is contained in:
Tomas Vondra 2020-04-07 18:03:24 +02:00
parent 4bd0ad9e44
commit d22782a539
3 changed files with 87 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/backend/commands/explain.c
View File

@ -2841,7 +2841,7 @@ show_incremental_sort_group_info(IncrementalSortGroupInfo *groupInfo,
ExplainOpenGroup("Sort Space", memoryName.data, true, es); ExplainOpenGroup("Sort Space", memoryName.data, true, es);
ExplainPropertyInteger("Average Sort Space Used", "kB", avgSpace, es); ExplainPropertyInteger("Average Sort Space Used", "kB", avgSpace, es);
ExplainPropertyInteger("Maximum Sort Space Used", "kB", ExplainPropertyInteger("Peak Sort Space Used", "kB",
groupInfo->maxMemorySpaceUsed, es); groupInfo->maxMemorySpaceUsed, es);
ExplainCloseGroup("Sort Spaces", memoryName.data, true, es); ExplainCloseGroup("Sort Spaces", memoryName.data, true, es);
@ -2858,7 +2858,7 @@ show_incremental_sort_group_info(IncrementalSortGroupInfo *groupInfo,
ExplainOpenGroup("Sort Space", diskName.data, true, es); ExplainOpenGroup("Sort Space", diskName.data, true, es);
ExplainPropertyInteger("Average Sort Space Used", "kB", avgSpace, es); ExplainPropertyInteger("Average Sort Space Used", "kB", avgSpace, es);
ExplainPropertyInteger("Maximum Sort Space Used", "kB", ExplainPropertyInteger("Peak Sort Space Used", "kB",
groupInfo->maxDiskSpaceUsed, es); groupInfo->maxDiskSpaceUsed, es);
ExplainCloseGroup("Sort Spaces", diskName.data, true, es); ExplainCloseGroup("Sort Spaces", diskName.data, true, es);
@ -2883,6 +2883,15 @@ show_incremental_sort_info(IncrementalSortState *incrsortstate,
if (!es->analyze) if (!es->analyze)
return; return;
/*
* Since we never have any prefix groups unless we've first sorted a full
* groups and transitioned modes (copying the tuples into a prefix group),
* we don't need to do anything if there were 0 full groups.
*
* We still have to continue after this block if there are no full groups,
* though, since it's possible that we have workers that did real work even
* if the leader didn't participate.
*/
if (fullsortGroupInfo->groupCount > 0) if (fullsortGroupInfo->groupCount > 0)
{ {
show_incremental_sort_group_info(fullsortGroupInfo, "Full-sort", true, es); show_incremental_sort_group_info(fullsortGroupInfo, "Full-sort", true, es);
@ -2914,6 +2923,13 @@ show_incremental_sort_info(IncrementalSortState *incrsortstate,
*/ */
fullsortGroupInfo = &incsort_info->fullsortGroupInfo; fullsortGroupInfo = &incsort_info->fullsortGroupInfo;
prefixsortGroupInfo = &incsort_info->prefixsortGroupInfo; prefixsortGroupInfo = &incsort_info->prefixsortGroupInfo;
/*
* Since we never have any prefix groups unless we've first sorted
* a full groups and transitioned modes (copying the tuples into a
* prefix group), we don't need to do anything if there were 0 full
* groups.
*/
if (fullsortGroupInfo->groupCount == 0 && if (fullsortGroupInfo->groupCount == 0 &&
prefixsortGroupInfo->groupCount == 0) prefixsortGroupInfo->groupCount == 0)
continue; continue;

134
src/test/regress/expected/incremental_sort.out
View File

@ -109,7 +109,7 @@ begin
for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop
for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop
node := jsonb_set(node, array[group_key, space_key, 'Average Sort Space Used'], '"NN"', false); node := jsonb_set(node, array[group_key, space_key, 'Average Sort Space Used'], '"NN"', false);
node := jsonb_set(node, array[group_key, space_key, 'Maximum Sort Space Used'], '"NN"', false); node := jsonb_set(node, array[group_key, space_key, 'Peak Sort Space Used'], '"NN"', false);
end loop; end loop;
end loop; end loop;
nodes := nodes || node; nodes := nodes || node;
@ -131,7 +131,7 @@ begin
for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop
group_stats := node->group_key; group_stats := node->group_key;
for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop
if (group_stats->space_key->'Maximum Sort Space Used')::bigint < (group_stats->space_key->'Maximum Sort Space Used')::bigint then if (group_stats->space_key->'Peak Sort Space Used')::bigint < (group_stats->space_key->'Peak Sort Space Used')::bigint then
raise exception '% has invalid max space < average space', group_key; raise exception '% has invalid max space < average space', group_key;
end if; end if;
end loop; end loop;
@ -545,34 +545,34 @@ select explain_analyze_without_memory('select * from (select * from t order by a
(9 rows) (9 rows)
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 55')); select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 55'));
jsonb_pretty jsonb_pretty
-------------------------------------------------- -------------------------------------------------
[ + [ +
{ + { +
"Sort Key": [ + "Sort Key": [ +
"t.a", + "t.a", +
"t.b" + "t.b" +
], + ], +
"Node Type": "Incremental Sort", + "Node Type": "Incremental Sort", +
"Actual Rows": 55, + "Actual Rows": 55, +
"Actual Loops": 1, + "Actual Loops": 1, +
"Presorted Key": [ + "Presorted Key": [ +
"t.a" + "t.a" +
], + ], +
"Parallel Aware": false, + "Parallel Aware": false, +
"Full-sort Groups": { + "Full-sort Groups": { +
"Group Count": 2, + "Group Count": 2, +
"Sort Methods Used": [ + "Sort Methods Used": [ +
"top-N heapsort", + "top-N heapsort", +
"quicksort" + "quicksort" +
], + ], +
"Sort Space Memory": { + "Sort Space Memory": { +
"Average Sort Space Used": "NN",+ "Peak Sort Space Used": "NN", +
"Maximum Sort Space Used": "NN" + "Average Sort Space Used": "NN"+
} + } +
}, + }, +
"Parent Relationship": "Outer" + "Parent Relationship": "Outer" +
} + } +
] ]
(1 row) (1 row)
@ -719,43 +719,43 @@ select explain_analyze_without_memory('select * from (select * from t order by a
(9 rows) (9 rows)
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 70')); select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 70'));
jsonb_pretty jsonb_pretty
-------------------------------------------------- -------------------------------------------------
[ + [ +
{ + { +
"Sort Key": [ + "Sort Key": [ +
"t.a", + "t.a", +
"t.b" + "t.b" +
], + ], +
"Node Type": "Incremental Sort", + "Node Type": "Incremental Sort", +
"Actual Rows": 70, + "Actual Rows": 70, +
"Actual Loops": 1, + "Actual Loops": 1, +
"Presorted Key": [ + "Presorted Key": [ +
"t.a" + "t.a" +
], + ], +
"Parallel Aware": false, + "Parallel Aware": false, +
"Full-sort Groups": { + "Full-sort Groups": { +
"Group Count": 1, + "Group Count": 1, +
"Sort Methods Used": [ + "Sort Methods Used": [ +
"quicksort" + "quicksort" +
], + ], +
"Sort Space Memory": { + "Sort Space Memory": { +
"Average Sort Space Used": "NN",+ "Peak Sort Space Used": "NN", +
"Maximum Sort Space Used": "NN" + "Average Sort Space Used": "NN"+
} + } +
}, + }, +
"Presorted Groups": { + "Presorted Groups": { +
"Group Count": 5, + "Group Count": 5, +
"Sort Methods Used": [ + "Sort Methods Used": [ +
"quicksort" + "quicksort" +
], + ], +
"Sort Space Memory": { + "Sort Space Memory": { +
"Average Sort Space Used": "NN",+ "Peak Sort Space Used": "NN", +
"Maximum Sort Space Used": "NN" + "Average Sort Space Used": "NN"+
} + } +
}, + }, +
"Parent Relationship": "Outer" + "Parent Relationship": "Outer" +
} + } +
] ]
(1 row) (1 row)

4
src/test/regress/sql/incremental_sort.sql
View File

@ -85,7 +85,7 @@ begin
for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop
for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop
node := jsonb_set(node, array[group_key, space_key, 'Average Sort Space Used'], '"NN"', false); node := jsonb_set(node, array[group_key, space_key, 'Average Sort Space Used'], '"NN"', false);
node := jsonb_set(node, array[group_key, space_key, 'Maximum Sort Space Used'], '"NN"', false); node := jsonb_set(node, array[group_key, space_key, 'Peak Sort Space Used'], '"NN"', false);
end loop; end loop;
end loop; end loop;
nodes := nodes || node; nodes := nodes || node;
@ -108,7 +108,7 @@ begin
for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop for group_key in select unnest(array['Full-sort Groups', 'Presorted Groups']::text[]) t loop
group_stats := node->group_key; group_stats := node->group_key;
for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop
if (group_stats->space_key->'Maximum Sort Space Used')::bigint < (group_stats->space_key->'Maximum Sort Space Used')::bigint then if (group_stats->space_key->'Peak Sort Space Used')::bigint < (group_stats->space_key->'Peak Sort Space Used')::bigint then
raise exception '% has invalid max space < average space', group_key; raise exception '% has invalid max space < average space', group_key;
end if; end if;
end loop; end loop;