From 01dbcd83720bf7a5e4bd7d80fc755c204b9568b7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=A4kel=C3=A4?= <markus.makela@mariadb.com>
Date: Tue, 14 Dec 2021 13:59:58 +0200
Subject: [PATCH] MXS-3915: Never cache autocommit queries

As both `SET autocommit=1` and `SET autocommit=0` share the same canonical
query form but do not have the same types, they should not be stored in
the cache.
---
 server/core/query_classifier.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/server/core/query_classifier.cc b/server/core/query_classifier.cc
index 924914844..30174cda9 100644
--- a/server/core/query_classifier.cc
+++ b/server/core/query_classifier.cc
@@ -399,7 +399,7 @@ public:
 
     ~QCInfoCacheScope()
     {
-        if (!m_canonical.empty())
+        if (store_in_cache())
         {
             void* pData = gwbuf_get_buffer_object_data(m_pStmt, GWBUF_PARSING_INFO);
             mxb_assert(pData);
@@ -412,6 +412,12 @@ public:
 private:
     GWBUF*      m_pStmt;
     std::string m_canonical;
+
+    bool store_in_cache() const
+    {
+        constexpr const int is_autocommit = QUERY_TYPE_ENABLE_AUTOCOMMIT | QUERY_TYPE_DISABLE_AUTOCOMMIT;
+        return !m_canonical.empty() && (qc_get_type_mask(m_pStmt) & is_autocommit) == 0;
+    }
 };
 }