From bf4d701cee0b4c96dc693eb9085a9a5d474a1afb Mon Sep 17 00:00:00 2001
From: hcduan <hcduan@tencent.com>
Date: Tue, 24 May 2022 13:32:14 +0800
Subject: [PATCH] [bugfix]#842 Bug#107366 REPLICATION ERROR WITH HASH_SCAN ROW
 SEARCH ALGORITHM FOR FUNCTIONAL INDEXES

Description
-----------
HASH_SCAN builds a hash of changes, scans the target table or
index, and applies any matching change for current entry. In the
build phase, it uses only the before-image, and skips any
after-image to avoid loose ends. However, previous implementation
(since WL#1075) computed generated columns for the skipped
after-image, thus causing replication error in some cases.

Analysis
--------
Rows_log_event::unpack_current_row() is used to unpack or skip a
row event. In the latter case, computing generated columns is
meaningless and sometimes harmful.

Fix
---
Never compute any generated columns for only-seek calls.
---
 .../suite/rpl/r/rpl_functional_index.result   | 19 ++++++++++++++
 .../suite/rpl/t/rpl_functional_index.test     | 25 +++++++++++++++++++
 sql/log_event.cc                              | 12 ++++-----
 3 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/mysql-test/suite/rpl/r/rpl_functional_index.result b/mysql-test/suite/rpl/r/rpl_functional_index.result
index 83efc20c8..87384703f 100644
--- a/mysql-test/suite/rpl/r/rpl_functional_index.result
+++ b/mysql-test/suite/rpl/r/rpl_functional_index.result
@@ -205,4 +205,23 @@ INSERT INTO t VALUES (1, 2);
 include/sync_slave_sql_with_master.inc
 include/diff_tables.inc [master:test.t,slave:test.t]
 DROP TABLE t;
+#
+# Bug#107366 REPLICATION ERROR WITH HASH_SCAN ROW SEARCH ALGORITHM FOR
+#            FUNCTIONAL INDEXES
+CREATE TABLE t1 (
+id int,
+c1 json NOT NULL,
+c2 int,
+KEY comp ((cast(c1 as unsigned array)))
+) ENGINE=InnoDB;
+insert into t1 values(1,'[1046, 2995]',1);
+update t1 set c2=2;
+select * from t1;
+id	c1	c2
+1	[1046, 2995]	2
+include/sync_slave_sql_with_master.inc
+select * from t1;
+id	c1	c2
+1	[1046, 2995]	2
+DROP TABLE t1;
 include/rpl_end.inc
diff --git a/mysql-test/suite/rpl/t/rpl_functional_index.test b/mysql-test/suite/rpl/t/rpl_functional_index.test
index 038955384..7425ebb2e 100644
--- a/mysql-test/suite/rpl/t/rpl_functional_index.test
+++ b/mysql-test/suite/rpl/t/rpl_functional_index.test
@@ -183,4 +183,29 @@ INSERT INTO t VALUES (1, 2);
 --connection master
 DROP TABLE t;
 
+--echo #
+--echo # Bug#107366 REPLICATION ERROR WITH HASH_SCAN ROW SEARCH ALGORITHM FOR
+--echo #            FUNCTIONAL INDEXES
+--connection master
+
+CREATE TABLE t1 (
+  id int,
+  c1 json NOT NULL,
+  c2 int,
+  KEY comp ((cast(c1 as unsigned array)))
+) ENGINE=InnoDB;
+
+insert into t1 values(1,'[1046, 2995]',1);
+
+update t1 set c2=2;
+
+select * from t1;
+
+--source include/sync_slave_sql_with_master.inc
+
+select * from t1;
+
+--connection master
+DROP TABLE t1;
+
 --source include/rpl_end.inc
diff --git a/sql/log_event.cc b/sql/log_event.cc
index 64f93d089..faa0f3b03 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -8174,12 +8174,12 @@ int Rows_log_event::unpack_current_row(const Relay_log_info *const rli,
               updatable_columns_view.get_included_fields_bitmap())) {
         return thd->get_stmt_da()->mysql_errno(); /* purecov: deadcode */
       }
-    }
-    if (is_after_image &&
-        !bitmap_is_clear_all(&this->m_table->fields_for_functional_indexes)) {
-      if (this->update_generated_columns(
-              this->m_table->fields_for_functional_indexes))
-        return thd->get_stmt_da()->mysql_errno(); /* purecov: deadcode */
+      if (is_after_image &&
+          !bitmap_is_clear_all(&this->m_table->fields_for_functional_indexes)) {
+        if (this->update_generated_columns(
+                this->m_table->fields_for_functional_indexes))
+          return thd->get_stmt_da()->mysql_errno(); /* purecov: deadcode */
+      }
     }
   }
 
-- 
2.32.0