Bug #27753193 ASSERTION `PREBUILT->TRX->ERROR_KEY_NUM <

HA_ALTER_INFO->KEY_COUNT'

Problem:
During OPTIMIZE TABLE operation, Simultaneously INSERT duplicate
entry into the table, then alter operation corresponds to optimize
table catches duplicate entry error while applying row logs.
If the table holds innodb generated GEN_CLUST_INDEX and the
duplicate entry error is on last unique column then
ha_innobase::inplace_alter_table() hits assert on
(m_prebuilt->trx->error_key_num < ha_alter_info->key_count).

Fix:
Added a check inside ha_innobase::inplace_alter_table(). If there
is innodb generated GEN_CLUST_INDEX in the table then
m_prebuilt->trx->error_key_num  and ha_alter_info->key_count could
be equal.

RB: 20081
Reviewed by : jimmy.yang@oracle.com

mysql-test/suite/innodb/r/innodb-alter-debug.result

@@ -52,3 +52,23 @@ SET DEBUG_SYNC = 'now SIGNAL s2';
 /* reap */ alter table t1 add b int, ALGORITHM=inplace;
 ERROR 23000: Duplicate entry '1' for key 'uk'
 drop table t1;
+#
+# Bug #27753193  ASSERTION `PREBUILT->TRX->ERROR_KEY_NUM <
+#                HA_ALTER_INFO->KEY_COUNT'
+CREATE TABLE t1 (a INT, UNIQUE KEY(a));
+INSERT INTO t1 VALUES (1);
+SET DEBUG_SYNC = 'row_log_table_apply1_before signal S1 WAIT_FOR S2';
+OPTIMIZE TABLE t1;;
+SET DEBUG_SYNC = 'now WAIT_FOR S1';
+INSERT INTO t1 VALUES (1);
+ERROR 23000: Duplicate entry '1' for key 'a'
+SET DEBUG_SYNC = 'now SIGNAL S2';
+/* reap */ OPTIMIZE TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	optimize	note	Table does not support optimize, doing recreate + analyze instead
+test.t1	optimize	error	Duplicate entry '1' for key 'a'
+test.t1	optimize	status	Operation failed
+Warnings:
+Error	1062	Duplicate entry '1' for key 'a'
+SET DEBUG_SYNC='RESET';
+DROP TABLE t1;

mysql-test/suite/innodb/t/innodb-alter-debug.test

@@ -75,3 +75,31 @@ drop table t1;
 
 # Wait till all disconnects are completed
 --source include/wait_until_count_sessions.inc
+
+--echo #
+--echo # Bug #27753193  ASSERTION `PREBUILT->TRX->ERROR_KEY_NUM <
+--echo #                HA_ALTER_INFO->KEY_COUNT'
+
+CREATE TABLE t1 (a INT, UNIQUE KEY(a));
+INSERT INTO t1 VALUES (1);
+
+SET DEBUG_SYNC = 'row_log_table_apply1_before signal S1 WAIT_FOR S2';
+--send OPTIMIZE TABLE t1;
+
+CONNECT (con1,localhost,root,,);
+CONNECTION con1;
+SET DEBUG_SYNC = 'now WAIT_FOR S1';
+--error ER_DUP_ENTRY
+INSERT INTO t1 VALUES (1);
+SET DEBUG_SYNC = 'now SIGNAL S2';
+
+CONNECTION default;
+--echo /* reap */ OPTIMIZE TABLE t1;
+--reap
+DISCONNECT con1;
+SET DEBUG_SYNC='RESET';
+
+DROP TABLE t1;
+
+# Wait till all disconnects are completed
+--source include/wait_until_count_sessions.inc

storage/innobase/handler/handler0alter.cc

@@ -4014,10 +4014,19 @@ ha_innobase::inplace_alter_table(
 			reporting a bogus duplicate key error. */
 			dup_key = NULL;
 		} else {
-			DBUG_ASSERT(prebuilt->trx->error_key_num
-				    < ha_alter_info->key_count);
-			dup_key = &ha_alter_info->key_info_buffer[
-				prebuilt->trx->error_key_num];
+			/* Check if there is generated cluster index column */
+			if (ctx->num_to_add_index > ha_alter_info->key_count) {
+				DBUG_ASSERT(prebuilt->trx->error_key_num
+					    <= ha_alter_info->key_count);
+				dup_key = &ha_alter_info->key_info_buffer[
+					prebuilt->trx->error_key_num - 1];
+			}
+			else {
+				DBUG_ASSERT(prebuilt->trx->error_key_num
+					    < ha_alter_info->key_count);
+				dup_key = &ha_alter_info->key_info_buffer[
+					prebuilt->trx->error_key_num];
+			}
 		}
 		print_keydup_error(altered_table, dup_key, MYF(0));
 		break;
@@ -4938,11 +4947,20 @@ commit_try_rebuild(
 				FTS_DOC_ID. */
 				dup_key = NULL;
 			} else {
-				DBUG_ASSERT(err_key <
-					    ha_alter_info->key_count);
-				dup_key = &ha_alter_info
-					->key_info_buffer[err_key];
+				if (ctx->num_to_add_index > ha_alter_info->key_count) {
+					DBUG_ASSERT(err_key <=
+						    ha_alter_info->key_count);
+					dup_key = &ha_alter_info
+						->key_info_buffer[err_key - 1];
+				}
+				else {
+					DBUG_ASSERT(err_key <
+						    ha_alter_info->key_count);
+					dup_key = &ha_alter_info
+						->key_info_buffer[err_key];
+				}
 			}
+
 			print_keydup_error(altered_table, dup_key, MYF(0));
 			DBUG_RETURN(true);
 		case DB_ONLINE_LOG_TOO_BIG: