Closes BrentOzarULTD#678

Closes BrentOzarULTD#678

Author: BlitzErik

sp_BlitzCache.sql

@@ -195,6 +195,7 @@ CREATE TABLE ##bou_BlitzCacheProcs (
 		index_ops AS (index_insert_count + index_update_count + index_delete_count + 
 					  cx_insert_count + cx_update_count + cx_delete_count +
 					  table_insert_count + table_update_count + table_delete_count),
+		is_large_scan BIT,
         SetOptions VARCHAR(MAX),
         Warnings VARCHAR(MAX)
     );
@@ -830,6 +831,7 @@ BEGIN
 		index_ops AS (index_insert_count + index_update_count + index_delete_count + 
 			  cx_insert_count + cx_update_count + cx_delete_count +
 			  table_insert_count + table_update_count + table_delete_count),
+		is_large_scan BIT,
         SetOptions VARCHAR(MAX),
         Warnings VARCHAR(MAX)
     );
@@ -2229,6 +2231,37 @@ BEGIN
 	OPTION (RECOMPILE) ;
 END ;
 
+IF (@v = 13 AND @build >= 4001)
+BEGIN
+	RAISERROR(N'Using 2016 SP1 estimated rows read to detect inefficient scans', 0, 1) WITH NOWAIT;
+	
+	WITH XMLNAMESPACES('http://schemas.microsoft.com/sqlserver/2004/07/showplan' AS p),
+	er AS (
+		SELECT 
+		r.SqlHandle, 
+		c.n.value('@EstimateRows', 'FLOAT') AS estimated_rows,
+		c.n.value('@EstimatedRowsRead', 'FLOAT') AS estimated_rows_read
+		FROM #relop AS r
+		CROSS APPLY r.relop.nodes('//p:RelOp') c(n) 
+		WHERE c.n.exist('@EstimatedRowsRead') = 1
+	), er2 AS (
+		SELECT *, 
+			CASE WHEN er.estimated_rows_read >= 100000
+					  AND er.estimated_rows * 10 < er.estimated_rows_read
+				 THEN 1
+				 ELSE 0
+			END AS is_large_scan
+		FROM er
+	)
+	UPDATE b
+	SET b.is_large_scan = er2.is_large_scan
+	FROM ##bou_BlitzCacheProcs b
+	JOIN er2 
+	ON b.SqlHandle = er2.SqlHandle 
+	WHERE er2.is_large_scan = 1
+	OPTION (RECOMPILE);
+END
+
 /* END Testing using XML nodes to speed up processing */
 RAISERROR(N'Gathering additional plan level information', 0, 1) WITH NOWAIT;
 WITH XMLNAMESPACES('http://schemas.microsoft.com/sqlserver/2004/07/showplan' AS p)
@@ -2516,7 +2549,8 @@ SET    Warnings = CASE WHEN QueryPlan IS NULL THEN 'We couldn''t find a plan for
 				  CASE WHEN is_computed_scalar = 1 THEN ', Computed Column UDF ' ELSE '' END  +
 				  CASE WHEN is_sort_expensive = 1 THEN ', Expensive Sort' ELSE '' END +
 				  CASE WHEN is_computed_filter = 1 THEN ', Filter UDF' ELSE '' END +
-				  CASE WHEN index_ops >= 5 THEN ', ' + CONVERT(VARCHAR(10), index_ops) + ' Indexes Modified' ELSE '' END 
+				  CASE WHEN index_ops >= 5 THEN ', ' + CONVERT(VARCHAR(10), index_ops) + ' Indexes Modified' ELSE '' END +
+				  CASE WHEN is_large_scan = 1 THEN ', Inefficient Scan' ELSE '' END
                   , 2, 200000) 
 				  END
 WHERE SPID = @@SPID
@@ -2844,7 +2878,8 @@ BEGIN
 				  CASE WHEN is_computed_scalar = 1 THEN '', 42 '' ELSE '' END +
 				  CASE WHEN is_sort_expensive = 1 THEN '', 43'' ELSE '''' END +
 				  CASE WHEN is_computed_filter = 1 THEN '', 44'' ELSE '''' END + 
-				  CASE WHEN index_ops >= 5 THEN  '', 45'' ELSE '''' END 
+				  CASE WHEN index_ops >= 5 THEN  '', 45'' ELSE '''' END +
+				  CASE WHEN is_large_scan = 1 THEN '', 46'' ELSE '''' END + 
 				  , 2, 200000) END AS opserver_warning , ' + @nl ;
     END
 
@@ -3489,7 +3524,20 @@ BEGIN
                      'Write Queries Are Hitting >= 5 Indexes',
                      'No URL yet',
                      'This can cause lots of hidden I/O -- Run sp_BLitzIndex for more information.') ;
-
+ 
+        IF EXISTS (SELECT 1/0
+                    FROM   ##bou_BlitzCacheProcs p
+                    WHERE  p.is_large_scan = 1
+  					AND SPID = @@SPID)
+             INSERT INTO ##bou_BlitzCacheResults (SPID, CheckID, Priority, FindingsGroup, Finding, URL, Details)
+             VALUES (@@SPID,
+                     46,
+                     100,
+                     'Inefficient Scan',
+                     'More than 10x rows read than returned',
+                     'No URL yet',
+                     'This looks for scans of >100k rows where the output is < 10x the scan.') ;
+ 
         IF EXISTS (SELECT 1/0
                    FROM   #plan_creation p
                    WHERE (p.percent_24 > 0 OR p.percent_4 > 0)