From d74ed48bdfdc394d41101cfe7126c6c26c37324c Mon Sep 17 00:00:00 2001
From: Vitaly Bruk <vitaly@madeiradata.com>
Date: Mon, 23 Dec 2024 16:28:33 +0200
Subject: [PATCH] Create Detecting Failed Forced Plans in Query Store.sql

This script identifies queries with forced plans that have failed with GENERAL_FAILURE in Query Store.
---
 ...ing Failed Forced Plans in Query Store.sql | 137 ++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 Query Store/Detecting Failed Forced Plans in Query Store.sql

diff --git a/Query Store/Detecting Failed Forced Plans in Query Store.sql b/Query Store/Detecting Failed Forced Plans in Query Store.sql
new file mode 100644
index 0000000..0e97f2c
--- /dev/null
+++ b/Query Store/Detecting Failed Forced Plans in Query Store.sql	
@@ -0,0 +1,137 @@
+/*
+	Created: Vitaly Bruk / MadeiraData
+	Date:	2024-12-23
+	
+	Description:
+		Query plans that have been forced in Query Store may end up with the forcing in a “failed” state for a variety of reasons.
+		Sometimes this might be that a structure in the forced plan is no longer valid - maybe an index that had been selected in the plan has been dropped or its definition has changed.
+		This script identifies queries with forced plans that have failed with GENERAL_FAILURE in Query Store.
+
+*/
+
+
+SET NOCOUNT ON;
+SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
+
+DECLARE
+	@WhatIf			BIT				= 0,		-- Set to 1 to only print the commands but not run them.
+	@database_name	SYSNAME			= NULL,		-- Leave NULL to check all databases or choose specific one
+	@sql			NVARCHAR(MAX);
+
+IF OBJECT_ID('tempdb.dbo.#FailedForcedPlans', 'U') IS NOT NULL
+BEGIN
+	DROP TABLE #FailedForcedPlans;
+END
+
+-- Temporary table to collect failed forced plans across databases
+CREATE TABLE #FailedForcedPlans
+							(
+								[database_name]			SYSNAME,
+								query_id				INT,
+								plan_id					INT,
+								failure_reason			NVARCHAR(128),
+								query_sql_text			NVARCHAR(MAX),
+								force_failure_count		INT
+							);
+
+-- Cursor to loop through all user databases
+DECLARE db_cursor CURSOR LOCAL FAST_FORWARD FOR
+
+	SELECT 
+		[name]
+	FROM 
+		sys.databases
+	WHERE
+		state_desc = 'ONLINE'						-- databases in online state only
+		AND user_access = 0							-- accessable databases only
+		AND is_query_store_on = 1					-- databases with QS enabled only
+		AND database_id > 4							-- exclude system databases
+		AND [name] != 'rdsadmin'					-- exclude AWS RDS system database
+		AND
+			(
+				@database_name IS NULL 
+				OR [name] = @database_name			-- specific databases only
+			);
+
+OPEN db_cursor;
+FETCH NEXT FROM db_cursor INTO @database_name;
+
+WHILE @@FETCH_STATUS = 0
+BEGIN
+	BEGIN TRY
+		SET @sql = '
+			SELECT 
+				DB_NAME(),
+				qsqp.query_id,
+				qsqp.plan_id,
+				qsqp.last_force_failure_reason_desc,
+				qsqt.query_sql_text,
+				qsqp.force_failure_count
+			FROM 
+				' + QUOTENAME(@database_name) + '.sys.query_store_plan AS qsqp
+				LEFT JOIN ' + QUOTENAME(@database_name) + '.sys.query_store_query AS qsq ON qsqp.query_id = qsq.query_id
+				LEFT JOIN ' + QUOTENAME(@database_name) + '.sys.query_store_query_text AS qsqt ON qsq.query_text_id = qsqt.query_text_id
+			WHERE 
+				qsqp.is_forced_plan = 1
+				AND qsqp.force_failure_count > 0
+				AND qsqp.last_force_failure_reason_desc = ''GENERAL_FAILURE''
+			OPTION (RECOMPILE);
+		';
+
+		IF @WhatIf != 0
+		BEGIN
+			PRINT @sql
+		END
+		ELSE
+		BEGIN
+            -- Execute dynamic SQL inside TRY block
+			BEGIN TRY
+                INSERT INTO #FailedForcedPlans ([database_name], query_id, plan_id, failure_reason, query_sql_text, force_failure_count)
+                EXEC sp_executesql @sql;
+            END TRY
+            BEGIN CATCH
+                PRINT 'Error executing dynamic SQL for database ' + @database_name + ': ' + ERROR_MESSAGE();
+            END CATCH;
+        END
+
+    END TRY
+    BEGIN CATCH
+        PRINT 'Error processing database ' + @database_name + ': ' + ERROR_MESSAGE();
+    END CATCH;
+
+    FETCH NEXT FROM db_cursor INTO @database_name;
+END;
+
+CLOSE db_cursor;
+DEALLOCATE db_cursor;
+
+IF @WhatIf = 0
+BEGIN
+	-- Output results
+	SELECT
+		[database_name],
+		query_id,
+		plan_id,
+		failure_reason,
+		query_sql_text,
+		force_failure_count,
+		CONCAT	(
+					CASE	
+						WHEN CAST (SERVERPROPERTY('EngineEdition') AS NVARCHAR(128)) BETWEEN 1 AND 4	-- SQL Server
+							OR CAST (SERVERPROPERTY('EngineEdition') AS NVARCHAR(128)) = 8				-- Azure SQL Managed Instance
+								THEN CONCAT('USE ', QUOTENAME ([database_name]), '; ')
+						WHEN CAST (SERVERPROPERTY('EngineEdition') AS NVARCHAR(128)) = 5				-- Azure SQL Database
+								THEN ''
+					END,
+					'EXEC sp_query_store_unforce_plan @query_id = ', query_id, ', @plan_id = ', plan_id, '; '
+				)	AS Script
+	FROM
+		#FailedForcedPlans
+	ORDER BY
+		[database_name],
+		query_id;
+
+END
+
+-- Cleanup
+DROP TABLE #FailedForcedPlans;