Merge pull request #3633 from BrentOzarULTD/3632_sp_BlitzCache_readable_secondaries

#3632 sp_BlitzCache readable replicas

Author: BrentOzar

README.md

@@ -180,6 +180,7 @@ Other common parameters include:
 * @ExportToExcel = 1 - turn this on, and it doesn't return XML fields that would hinder you from copy/pasting the data into Excel.
 * @ExpertMode = 1 - turn this on, and you get more columns with more data. Doesn't take longer to run though.
 * @IgnoreSystemDBs = 0 - if you want to show queries in master/model/msdb. By default we hide these. Additionally hides queries from databases named `dbadmin`, `dbmaintenance`, and `dbatools`.
+* @IgnoreReadableReplicaDBs = 0 - if you want to analyze the plan cache on an Availability Group readable replica. You will also have to connect to the replica using ApplicationIntent = ReadOnly, since SQL Server itself will abort queries that try to do work in readable secondaries.
 * @MinimumExecutionCount = 0 - in servers like data warehouses where lots of queries only run a few times, you can set a floor number for examination.
 
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sp_BlitzCache.sql

@@ -256,6 +256,7 @@ ALTER PROCEDURE dbo.sp_BlitzCache
     @DurationFilter DECIMAL(38,4) = NULL ,
     @HideSummary BIT = 0 ,
     @IgnoreSystemDBs BIT = 1 ,
+    @IgnoreReadableReplicaDBs BIT = 1 ,
     @OnlyQueryHashes VARCHAR(MAX) = NULL ,
     @IgnoreQueryHashes VARCHAR(MAX) = NULL ,
     @OnlySqlHandles VARCHAR(MAX) = NULL ,
@@ -1405,7 +1406,7 @@ CREATE TABLE #plan_usage
 );
 
 
-IF EXISTS (SELECT * FROM sys.all_objects o WHERE o.name = 'dm_hadr_database_replica_states')
+IF @IgnoreReadableReplicaDBs = 1 AND EXISTS (SELECT * FROM sys.all_objects o WHERE o.name = 'dm_hadr_database_replica_states')
 BEGIN
 	RAISERROR('Checking for Read intent databases to exclude',0,0) WITH NOWAIT;
 
@@ -1824,7 +1825,7 @@ IF @VersionShowsAirQuoteActualPlans = 1
 
 SET @body += N'        WHERE  1 = 1 ' +  @nl ;
 
-	IF EXISTS (SELECT * FROM sys.all_objects o WHERE o.name = 'dm_hadr_database_replica_states')
+	IF @IgnoreReadableReplicaDBs = 1 AND EXISTS (SELECT * FROM sys.all_objects o WHERE o.name = 'dm_hadr_database_replica_states')
     BEGIN
     RAISERROR(N'Ignoring readable secondaries databases by default', 0, 1) WITH NOWAIT;
     SET @body += N'               AND CAST(xpa.value AS INT) NOT IN (SELECT database_id FROM #ReadableDBs)' + @nl ;