Backport ClickHouse#84026 to 25.6: Disable query condition cache for recursive CTEs

Author: robot-clickhouse

src/Processors/Sources/RecursiveCTESource.cpp

@@ -26,6 +26,7 @@ namespace DB
 namespace Setting
 {
     extern const SettingsUInt64 max_recursive_cte_evaluation_depth;
+    extern const SettingsBool use_query_condition_cache;
 }
 
 namespace ErrorCodes
@@ -176,6 +177,10 @@ class RecursiveCTEChunkGenerator
                 recursive_subquery_settings[Setting::max_recursive_cte_evaluation_depth].value,
                 recursive_cte_union_node->formatASTForErrorMessage());
 
+        /// Workaround for issue 84026: Usage of the query condition cache with recursive CTEs caused wrong results
+        if (recursive_step > 0 && recursive_subquery_settings[Setting::use_query_condition_cache])
+            recursive_query_context->setSetting("use_query_condition_cache", false);
+
         auto & query_to_execute = recursive_step > 0 ? recursive_query : non_recursive_query;
         ++recursive_step;
 

src/Storages/MergeTree/MergeTreeSelectProcessor.cpp

@@ -196,7 +196,7 @@ ChunkAndProgress MergeTreeSelectProcessor::read()
                                 part_name,
                                 output->getHash(),
                                 reader_settings.query_condition_cache_store_conditions_as_plaintext
-                                    ? prewhere_info->prewhere_actions.getNames()[0]
+                                    ? output->result_name
                                     : "",
                                 task->getPrewhereUnmatchedMarks(),
                                 data_part->index_granularity->getMarksCount(),

tests/queries/0_stateless/03229_query_condition_cache_recursive_cte.reference

@@ -0,0 +1,9 @@
+-- Prepare data
+-- First run
+uuid2
+uuid3
+uuid4
+-- Second run
+uuid2
+uuid3
+uuid4

tests/queries/0_stateless/03229_query_condition_cache_recursive_cte.sql

@@ -0,0 +1,62 @@
+-- Tags: no-parallel
+-- Tag no-parallel: Messes with internal cache
+
+-- Test for issue #81506 (recursive CTEs return wrong results if the query condition cache is on)
+
+SET allow_experimental_analyzer = 1; -- needed by recursive CTEs
+
+-- Start from a clean query condition cache
+SYSTEM DROP QUERY CONDITION CACHE;
+
+SELECT '-- Prepare data';
+
+DROP TABLE IF EXISTS tab;
+CREATE TABLE tab
+(
+    id String,
+    parent String,
+)
+ENGINE = MergeTree
+ORDER BY tuple();
+
+INSERT INTO tab (id, parent) VALUES
+  ('uuid1', 'uuid2'),
+  ('uuid3', 'uuid4'),
+  ('uuid4', 'uuid2'),
+  ('uuid2', 'empty'),
+  ('uuid5', 'uuid2'),
+  ('uuid6', 'uuid4');
+
+SELECT '-- First run';
+
+WITH RECURSIVE
+        recursive AS (
+                SELECT id FROM tab WHERE id = 'uuid3'
+            UNION ALL
+                SELECT parent AS id
+                FROM tab
+                WHERE tab.id IN recursive AND parent != 'empty'
+                GROUP BY parent
+        )
+SELECT *
+FROM recursive
+GROUP BY id
+ORDER BY id;
+
+SELECT '-- Second run'; -- same query
+
+WITH RECURSIVE
+        recursive AS (
+                SELECT id FROM tab WHERE id = 'uuid3'
+            UNION ALL
+                SELECT parent AS id
+                FROM tab
+                WHERE tab.id IN recursive AND parent != 'empty'
+                GROUP BY parent
+        )
+SELECT *
+FROM recursive
+GROUP BY id
+ORDER BY id;
+
+DROP TABLE tab;