Merge pull request ClickHouse#78720 from azat/system.tables-mutations

azat · web-flow · commit 936bbc737106 · 2025-04-05T16:30:31.000Z
Optimize system.tables for *_mutations access
diff --git a/src/Storages/System/StorageSystemTables.cpp b/src/Storages/System/StorageSystemTables.cpp
@@ -718,7 +718,9 @@ class TablesBlockSource : public ISource
 
                 if (table_merge_tree)
                 {
-                    auto mutation_counters = table_merge_tree->getMutationCounters();
+                    MutationCounters mutation_counters;
+                    if (columns_mask[src_index] || columns_mask[src_index + 1] || columns_mask[src_index + 2])
+                        mutation_counters = table_merge_tree->getMutationCounters();
 
                     if (columns_mask[src_index++])
                         res_columns[res_index++]->insert(mutation_counters.num_data);

Original file line number	Diff line number	Diff line change
`@@ -718,7 +718,9 @@ class TablesBlockSource : public ISource`
`718`	`718`
`719`	`719`	`if (table_merge_tree)`
`720`	`720`	`{`
`721`		`- auto mutation_counters = table_merge_tree->getMutationCounters();`
	`721`	`+ MutationCounters mutation_counters;`
	`722`	`+ if (columns_mask[src_index] \|\| columns_mask[src_index + 1] \|\| columns_mask[src_index + 2])`
	`723`	`+ mutation_counters = table_merge_tree->getMutationCounters();`
`722`	`724`
`723`	`725`	`if (columns_mask[src_index++])`
`724`	`726`	`res_columns[res_index++]->insert(mutation_counters.num_data);`