From 99d7f5d8f34f6b0e77a7f6b371f9e4414dd9c1a1 Mon Sep 17 00:00:00 2001
From: Erik Darling <2136037+erikdarlingdata@users.noreply.github.com>
Date: Fri, 27 Feb 2026 06:59:16 -0500
Subject: [PATCH] Skip non-readable AG secondary databases in cross-database
 collectors (#325)

Collectors that iterate databases and USE/query into them now exclude
AG secondary replicas configured with READ_ONLY connections, which
reject non-read-intent sessions with "not accessible for queries" errors.

Filter uses sys.availability_replicas.secondary_role_allow_connections_desc
to identify secondaries that won't accept our connection type. Databases
on primaries, non-AG databases, and secondaries with ALL connections
continue to be collected normally.

Changed locations:
- install/39_collect_database_configuration.sql (scoped config cursor)
- install/09_collect_query_store.sql (QS discovery cursor)
- Lite/RemoteCollectorService.ServerConfig.cs (scoped config db list)
- Lite/RemoteCollectorService.QueryStore.cs (QS discovery cursor)

Clean install verified on sql2016 with zero errors.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 .../RemoteCollectorService.QueryStore.cs        | 17 +++++++++++++++++
 .../RemoteCollectorService.ServerConfig.cs      | 17 +++++++++++++++++
 install/09_collect_query_store.sql              | 17 +++++++++++++++++
 install/39_collect_database_configuration.sql   | 17 +++++++++++++++++
 4 files changed, 68 insertions(+)

diff --git a/Lite/Services/RemoteCollectorService.QueryStore.cs b/Lite/Services/RemoteCollectorService.QueryStore.cs
index 737dd7f..53f8162 100644
--- a/Lite/Services/RemoteCollectorService.QueryStore.cs
+++ b/Lite/Services/RemoteCollectorService.QueryStore.cs
@@ -48,6 +48,23 @@ WHERE d.database_id > 4
     AND   d.database_id < 32761
     AND   d.state_desc = N'ONLINE'
     AND   d.name <> N'PerformanceMonitor'
+    AND   d.database_id NOT IN
+          (
+              SELECT
+                  d2.database_id
+              FROM sys.databases AS d2
+              JOIN sys.availability_replicas AS r
+                ON d2.replica_id = r.replica_id
+              WHERE NOT EXISTS
+                    (
+                        SELECT
+                            1/0
+                        FROM sys.dm_hadr_availability_group_states AS s
+                        WHERE s.primary_replica = r.replica_server_name
+                    )
+              AND   r.secondary_role_allow_connections_desc = N'READ_ONLY'
+              AND   r.replica_server_name = @@SERVERNAME
+          )
     OPTION(RECOMPILE);
 
 OPEN db_check;
diff --git a/Lite/Services/RemoteCollectorService.ServerConfig.cs b/Lite/Services/RemoteCollectorService.ServerConfig.cs
index 9adad48..b0f325f 100644
--- a/Lite/Services/RemoteCollectorService.ServerConfig.cs
+++ b/Lite/Services/RemoteCollectorService.ServerConfig.cs
@@ -336,6 +336,23 @@ FROM sys.databases AS d
 AND   d.database_id < 32761
 AND   d.name <> N'PerformanceMonitor'
 AND   d.state_desc = N'ONLINE'
+AND   d.database_id NOT IN
+      (
+          SELECT
+              d2.database_id
+          FROM sys.databases AS d2
+          JOIN sys.availability_replicas AS r
+            ON d2.replica_id = r.replica_id
+          WHERE NOT EXISTS
+                (
+                    SELECT
+                        1/0
+                    FROM sys.dm_hadr_availability_group_states AS s
+                    WHERE s.primary_replica = r.replica_server_name
+                )
+          AND   r.secondary_role_allow_connections_desc = N'READ_ONLY'
+          AND   r.replica_server_name = @@SERVERNAME
+      )
 ORDER BY d.name
 OPTION(RECOMPILE);";
 
diff --git a/install/09_collect_query_store.sql b/install/09_collect_query_store.sql
index a1cac83..7505695 100644
--- a/install/09_collect_query_store.sql
+++ b/install/09_collect_query_store.sql
@@ -291,6 +291,23 @@ BEGIN
             AND   d.is_read_only = 0
             AND   d.name <> N'PerformanceMonitor'
             AND   d.database_id < 32761 /*exclude contained AG system databases*/
+            AND   d.database_id NOT IN
+                  (
+                      SELECT
+                          d2.database_id
+                      FROM sys.databases AS d2
+                      JOIN sys.availability_replicas AS r
+                        ON d2.replica_id = r.replica_id
+                      WHERE NOT EXISTS
+                            (
+                                SELECT
+                                    1/0
+                                FROM sys.dm_hadr_availability_group_states AS s
+                                WHERE s.primary_replica = r.replica_server_name
+                            )
+                      AND   r.secondary_role_allow_connections_desc = N'READ_ONLY'
+                      AND   r.replica_server_name = @@SERVERNAME
+                  )
             OPTION(RECOMPILE);
 
         OPEN @db_check_cursor;
diff --git a/install/39_collect_database_configuration.sql b/install/39_collect_database_configuration.sql
index 199f155..1bac443 100644
--- a/install/39_collect_database_configuration.sql
+++ b/install/39_collect_database_configuration.sql
@@ -165,6 +165,23 @@ BEGIN
             AND   d.name != DB_NAME()
             AND   d.state_desc = N'ONLINE'
             AND   d.database_id < 32761 /*exclude contained AG system databases*/
+            AND   d.database_id NOT IN
+                  (
+                      SELECT
+                          d2.database_id
+                      FROM sys.databases AS d2
+                      JOIN sys.availability_replicas AS r
+                        ON d2.replica_id = r.replica_id
+                      WHERE NOT EXISTS
+                            (
+                                SELECT
+                                    1/0
+                                FROM sys.dm_hadr_availability_group_states AS s
+                                WHERE s.primary_replica = r.replica_server_name
+                            )
+                      AND   r.secondary_role_allow_connections_desc = N'READ_ONLY'
+                      AND   r.replica_server_name = @@SERVERNAME
+                  )
             ORDER BY
                 d.name
             OPTION (RECOMPILE);