rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Rework EXPLAIN format for incremental sort 

The explain format used by incremental sort was somewhat inconsistent
with other nodes, making it harder to parse and understand. This commit
addresses that by

 - adding an extra space to better separate groups of values

 - using colons instead of equal signs to separate key/value

 - properly capitalizing first letter of a key

 - using separate lines for full and pre-sorted groups

These changes were proposed by Justin Pryzby and mostly copy the final
explain format used to report WAL usage.

Author: Justin Pryzby
Reviewed-by: James Coleman
Discussion: https://postgr.es/m/20200419023625.GP26953@telsasoft.com
This commit is contained in:
Tomas Vondra 2020-05-12 20:04:39 +02:00
parent 1a40d37a9f
commit 6a918c3ac8
3 changed files with 22 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/backend/commands/explain.c
View File

@ -2778,7 +2778,7 @@ show_incremental_sort_group_info(IncrementalSortGroupInfo *groupInfo,
{
if (indent)
appendStringInfoSpaces(es->str, es->indent * 2);
appendStringInfo(es->str, "%s Groups: " INT64_FORMAT " Sort Method", groupLabel,
appendStringInfo(es->str, "%s Groups: " INT64_FORMAT " Sort Method", groupLabel,
groupInfo->groupCount);
/* plural/singular based on methodNames size */
if (list_length(methodNames) > 1)
@ -2798,9 +2798,9 @@ show_incremental_sort_group_info(IncrementalSortGroupInfo *groupInfo,
const char *spaceTypeName;
spaceTypeName = tuplesort_space_type_name(SORT_SPACE_TYPE_MEMORY);
appendStringInfo(es->str, " %s: avg=%ldkB peak=%ldkB",
appendStringInfo(es->str, " Average %s: %ldkB Peak %s: %ldkB",
spaceTypeName, avgSpace,
groupInfo->maxMemorySpaceUsed);
spaceTypeName, groupInfo->maxMemorySpaceUsed);
}
if (groupInfo->maxDiskSpaceUsed > 0)
@ -2810,12 +2810,9 @@ show_incremental_sort_group_info(IncrementalSortGroupInfo *groupInfo,
const char *spaceTypeName;
spaceTypeName = tuplesort_space_type_name(SORT_SPACE_TYPE_DISK);
/* Add a semicolon separator only if memory stats were printed. */
if (groupInfo->maxMemorySpaceUsed > 0)
appendStringInfo(es->str, ";");
appendStringInfo(es->str, " %s: avg=%ldkB peak=%ldkB",
appendStringInfo(es->str, " Average %s: %ldkB Peak %s: %ldkB",
spaceTypeName, avgSpace,
groupInfo->maxDiskSpaceUsed);
spaceTypeName, groupInfo->maxDiskSpaceUsed);
}
}
else
@ -2899,8 +2896,8 @@ show_incremental_sort_info(IncrementalSortState *incrsortstate,
if (prefixsortGroupInfo->groupCount > 0)
{
if (es->format == EXPLAIN_FORMAT_TEXT)
appendStringInfo(es->str, " ");
show_incremental_sort_group_info(prefixsortGroupInfo, "Presorted", false, es);
appendStringInfo(es->str, "\n");
show_incremental_sort_group_info(prefixsortGroupInfo, "Pre-sorted", true, es);
}
if (es->format == EXPLAIN_FORMAT_TEXT)
appendStringInfo(es->str, "\n");
@ -2942,8 +2939,8 @@ show_incremental_sort_info(IncrementalSortState *incrsortstate,
if (prefixsortGroupInfo->groupCount > 0)
{
if (es->format == EXPLAIN_FORMAT_TEXT)
appendStringInfo(es->str, " ");
show_incremental_sort_group_info(prefixsortGroupInfo, "Presorted", false, es);
appendStringInfo(es->str, "\n");
show_incremental_sort_group_info(prefixsortGroupInfo, "Pre-sorted", true, es);
}
if (es->format == EXPLAIN_FORMAT_TEXT)
appendStringInfo(es->str, "\n");

21
src/test/regress/expected/incremental_sort.out
View File

@ -106,7 +106,7 @@ declare
space_key text;
begin
for node in select * from jsonb_array_elements(explain_analyze_inc_sort_nodes(query)) t loop
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', 'Pre-sorted Groups']::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, 'Peak Sort Space Used'], '"NN"', false);
@ -128,7 +128,7 @@ declare
space_key text;
begin
for node in select * from jsonb_array_elements(explain_analyze_inc_sort_nodes(query)) t loop
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', 'Pre-sorted Groups']::text[]) t loop
group_stats := node->group_key;
for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop
if (group_stats->space_key->'Peak Sort Space Used')::bigint < (group_stats->space_key->'Peak Sort Space Used')::bigint then
@ -533,13 +533,13 @@ select * from (select * from t order by a) s order by a, b limit 55;
-- Test EXPLAIN ANALYZE with only a fullsort group.
select explain_analyze_without_memory('select * from (select * from t order by a) s order by a, b limit 55');
explain_analyze_without_memory
------------------------------------------------------------------------------------------------
explain_analyze_without_memory
---------------------------------------------------------------------------------------------------------------
Limit (actual rows=55 loops=1)
-> Incremental Sort (actual rows=55 loops=1)
Sort Key: t.a, t.b
Presorted Key: t.a
Full-sort Groups: 2 Sort Methods: top-N heapsort, quicksort Memory: avg=NNkB peak=NNkB
Full-sort Groups: 2 Sort Methods: top-N heapsort, quicksort Average Memory: NNkB Peak Memory: NNkB
-> Sort (actual rows=101 loops=1)
Sort Key: t.a
Sort Method: quicksort Memory: NNkB
@ -708,18 +708,19 @@ select * from t left join (select * from (select * from t order by a) v order by
rollback;
-- Test EXPLAIN ANALYZE with both fullsort and presorted groups.
select explain_analyze_without_memory('select * from (select * from t order by a) s order by a, b limit 70');
explain_analyze_without_memory
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
explain_analyze_without_memory
----------------------------------------------------------------------------------------------------------------
Limit (actual rows=70 loops=1)
-> Incremental Sort (actual rows=70 loops=1)
Sort Key: t.a, t.b
Presorted Key: t.a
Full-sort Groups: 1 Sort Method: quicksort Memory: avg=NNkB peak=NNkB Presorted Groups: 5 Sort Methods: top-N heapsort, quicksort Memory: avg=NNkB peak=NNkB
Full-sort Groups: 1 Sort Method: quicksort Average Memory: NNkB Peak Memory: NNkB
Pre-sorted Groups: 5 Sort Methods: top-N heapsort, quicksort Average Memory: NNkB Peak Memory: NNkB
-> Sort (actual rows=1000 loops=1)
Sort Key: t.a
Sort Method: quicksort Memory: NNkB
-> Seq Scan on t (actual rows=1000 loops=1)
(9 rows)
(10 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'));
jsonb_pretty
@ -747,7 +748,7 @@ select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from
"Average Sort Space Used": "NN"+
} +
}, +
"Presorted Groups": { +
"Pre-sorted Groups": { +
"Group Count": 5, +
"Sort Methods Used": [ +
"top-N heapsort", +

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

@ -82,7 +82,7 @@ declare
space_key text;
begin
for node in select * from jsonb_array_elements(explain_analyze_inc_sort_nodes(query)) t loop
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', 'Pre-sorted Groups']::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, 'Peak Sort Space Used'], '"NN"', false);
@ -105,7 +105,7 @@ declare
space_key text;
begin
for node in select * from jsonb_array_elements(explain_analyze_inc_sort_nodes(query)) t loop
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', 'Pre-sorted Groups']::text[]) t loop
group_stats := node->group_key;
for space_key in select unnest(array['Sort Space Memory', 'Sort Space Disk']::text[]) t loop
if (group_stats->space_key->'Peak Sort Space Used')::bigint < (group_stats->space_key->'Peak Sort Space Used')::bigint then