Merge #98248

98248: opt: enable optimizer_always_use_histograms by default r=rytaft a=rytaft This commit enables the new session setting, `optimizer_always_use_histograms`, by default. This ensures that the optimizer always uses histograms when available to calculate the statistics of every plan that it explores. Enabling this setting can prevent the optimizer from choosing a suboptimal index when statistics for a table are stale. Informs #64570 Release note: None Co-authored-by: Rebecca Taft <[email protected]>
cockroachdb · Mar 9, 2023 · 721dcb2 · 721dcb2
2 parents 9b05952 + c0e4fc3
commit 721dcb2
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Showing 4 changed files with 5 additions and 5 deletions.
diff --git a/pkg/sql/logictest/testdata/logic_test/information_schema b/pkg/sql/logictest/testdata/logic_test/information_schema
@@ -5016,7 +5016,7 @@ null_ordered_last                                     off
 on_update_rehome_row_enabled                          on
 opt_split_scan_limit                                  2048
 optimizer                                             on
-optimizer_always_use_histograms                       off
+optimizer_always_use_histograms                       on
 optimizer_use_forecasts                               on
 optimizer_use_histograms                              on
 optimizer_use_improved_disjunction_stats              on

diff --git a/pkg/sql/logictest/testdata/logic_test/pg_catalog b/pkg/sql/logictest/testdata/logic_test/pg_catalog
@@ -2647,7 +2647,7 @@ node_id                                               1                   NULL
 null_ordered_last                                     off                 NULL      NULL        NULL        string
 on_update_rehome_row_enabled                          on                  NULL      NULL        NULL        string
 opt_split_scan_limit                                  2048                NULL      NULL        NULL        string
-optimizer_always_use_histograms                       off                 NULL      NULL        NULL        string
+optimizer_always_use_histograms                       on                  NULL      NULL        NULL        string
 optimizer_use_forecasts                               on                  NULL      NULL        NULL        string
 optimizer_use_histograms                              on                  NULL      NULL        NULL        string
 optimizer_use_improved_disjunction_stats              on                  NULL      NULL        NULL        string
@@ -2795,7 +2795,7 @@ node_id                                               1                   NULL
 null_ordered_last                                     off                 NULL  user     NULL      off                 off
 on_update_rehome_row_enabled                          on                  NULL  user     NULL      on                  on
 opt_split_scan_limit                                  2048                NULL  user     NULL      2048                2048
-optimizer_always_use_histograms                       off                 NULL  user     NULL      off                 off
+optimizer_always_use_histograms                       on                  NULL  user     NULL      on                  on
 optimizer_use_forecasts                               on                  NULL  user     NULL      on                  on
 optimizer_use_histograms                              on                  NULL  user     NULL      on                  on
 optimizer_use_improved_disjunction_stats              on                  NULL  user     NULL      on                  on

diff --git a/pkg/sql/logictest/testdata/logic_test/show_source b/pkg/sql/logictest/testdata/logic_test/show_source
@@ -109,7 +109,7 @@ node_id                                               1
 null_ordered_last                                     off
 on_update_rehome_row_enabled                          on
 opt_split_scan_limit                                  2048
-optimizer_always_use_histograms                       off
+optimizer_always_use_histograms                       on
 optimizer_use_forecasts                               on
 optimizer_use_histograms                              on
 optimizer_use_improved_disjunction_stats              on

diff --git a/pkg/sql/vars.go b/pkg/sql/vars.go
@@ -2530,7 +2530,7 @@ var varGen = map[string]sessionVar{
 		Get: func(evalCtx *extendedEvalContext, _ *kv.Txn) (string, error) {
 			return formatBoolAsPostgresSetting(evalCtx.SessionData().OptimizerAlwaysUseHistograms), nil
 		},
-		GlobalDefault: globalFalse,
+		GlobalDefault: globalTrue,
 	},
 }