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

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 06f4414109c0cc8ec911f5780441819418fc3f6d..05f4d4c2c2bb72391a18cb1100eed0ae20db4a5e 100644 (file)
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -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");

diff --git a/src/test/regress/expected/incremental_sort.out b/src/test/regress/expected/incremental_sort.out
index 21d2d8b5fd80bada09dd2843d7e11d66aad3fa3c..53accd0df97d1d0e493f43f1e92bc8fcf989fddc 100644 (file)
--- a/src/test/regress/expected/incremental_sort.out
+++ b/src/test/regress/expected/incremental_sort.out
@@ -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",              +

diff --git a/src/test/regress/sql/incremental_sort.sql b/src/test/regress/sql/incremental_sort.sql
index fa2e320e9ae50d4cc818418227c6e8d8f2cafc87..373e62ac13a19e60f40a8ecabfd448ab49de59f8 100644 (file)
--- a/src/test/regress/sql/incremental_sort.sql
+++ b/src/test/regress/sql/incremental_sort.sql
@@ -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