Don't try to EXPLAIN select_db calls

2 files changed, 6 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/explain_subscriber.rb b/activerecord/lib/active_record/explain_subscriber.rb
index a3bc56d600..6a49936644 100644
--- a/activerecord/lib/active_record/explain_subscriber.rb
+++ b/activerecord/lib/active_record/explain_subscriber.rb
@@ -19,7 +19,7 @@ module ActiveRecord
     # On the other hand, we want to monitor the performance of our real database
     # queries, not the performance of the access to the query cache.
     IGNORED_PAYLOADS = %w(SCHEMA EXPLAIN CACHE)
-    EXPLAINED_SQLS = /\A\s*(select|update|delete|insert)/i
+    EXPLAINED_SQLS = /\A\s*(select|update|delete|insert)\b/i
     def ignore_payload?(payload)
       payload[:exception] || IGNORED_PAYLOADS.include?(payload[:name]) || payload[:sql] !~ EXPLAINED_SQLS
     end
diff --git a/activerecord/test/cases/explain_subscriber_test.rb b/activerecord/test/cases/explain_subscriber_test.rb
index fb53a92c89..b00e2744b9 100644
--- a/activerecord/test/cases/explain_subscriber_test.rb
+++ b/activerecord/test/cases/explain_subscriber_test.rb
@@ -43,6 +43,11 @@ if ActiveRecord::Base.connection.supports_explain?
       assert queries.empty?
     end
 
+    def test_collects_nothing_if_the_statement_is_only_partially_matched
+      SUBSCRIBER.finish(nil, nil, name: 'SQL', sql: 'select_db yo_mama')
+      assert queries.empty?
+    end
+
     def teardown
       ActiveRecord::ExplainRegistry.reset
     end