MDEV-25872 InnoDB: Assertion failure in row_merge_read_clustered_index upon ALTER on table with indexed virtual columns

- InnoDB fails to check DB_COMPUTE_VALUE_FAILED error in
row_merge_read_clustered_index() and wrongly asserts that
the buffer shouldn't be ran out of memory. Alter table
should give warning when the column value is being
truncated.

mysql-test/suite/gcol/r/gcol_keys_innodb.result

@@ -691,6 +691,8 @@ a	b	c
 1	127	0
 SET STATEMENT sql_mode = 'NO_ENGINE_SUBSTITUTION' FOR
 ALTER TABLE t ADD UNIQUE INDEX (c(1));
+Warnings:
+Warning	1264	Out of range value for column 'b' at row 1
 SELECT * FROM t WHERE c = '0';
 a	b	c
 1	127	0

mysql-test/suite/gcol/r/innodb_virtual_index.result

@@ -266,3 +266,23 @@ CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 DROP TABLE t1;
+#
+# MDEV-25872 InnoDB: Assertion failure in row_merge_read_clustered_index
+#	upon ALTER on table with indexed virtual columns
+#
+CREATE TABLE t1 (
+id BIGINT AUTO_INCREMENT PRIMARY KEY,
+a INT,
+va INT ZEROFILL AS (a) VIRTUAL,
+b TIMESTAMP,
+c CHAR(204),
+vc CHAR(8),
+KEY(vc,c(64),b,va)
+) ENGINE=InnoDB CHARACTER SET utf32;
+INSERT INTO t1 (id) SELECT NULL FROM seq_1_to_75;
+INSERT IGNORE INTO t1 (id, a) VALUES (NULL, -1);
+Warnings:
+Warning	1264	Out of range value for column 'va' at row 1
+ALTER TABLE t1 FORCE;
+ERROR 22003: Out of range value for column 'va' at row 1
+DROP TABLE t1;

mysql-test/suite/gcol/t/innodb_virtual_index.opt

@@ -0,0 +1 @@
+--innodb_sort_buffer_size=64k

mysql-test/suite/gcol/t/innodb_virtual_index.test

@@ -1,4 +1,5 @@
 --source include/have_innodb.inc
+--source include/have_sequence.inc
 
 # Ensure that the history list length will actually be decremented by purge.
 SET @saved_frequency = @@GLOBAL.innodb_purge_rseg_truncate_frequency;
@@ -281,3 +282,23 @@ ROLLBACK;
 SELECT * FROM t1;
 CHECK TABLE t1;
 DROP TABLE t1;
+
+--echo #
+--echo # MDEV-25872 InnoDB: Assertion failure in row_merge_read_clustered_index
+--echo #	upon ALTER on table with indexed virtual columns
+--echo #
+
+CREATE TABLE t1 (
+  id BIGINT AUTO_INCREMENT PRIMARY KEY,
+  a INT,
+  va INT ZEROFILL AS (a) VIRTUAL,
+  b TIMESTAMP,
+  c CHAR(204),
+  vc CHAR(8),
+  KEY(vc,c(64),b,va)
+) ENGINE=InnoDB CHARACTER SET utf32;
+INSERT INTO t1 (id) SELECT NULL FROM seq_1_to_75;
+INSERT IGNORE INTO t1 (id, a) VALUES (NULL, -1);
+--error ER_WARN_DATA_OUT_OF_RANGE
+ALTER TABLE t1 FORCE;
+DROP TABLE t1;

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

@@ -1041,7 +1041,9 @@ CREATE TABLE t1 (a INT NOT NULL DEFAULT 0) ENGINE=InnoDB;
 iNSERT INTO t1 VALUES (10);
 ALTER TABLE t1 ADD b DATE NOT NULL DEFAULT if(unix_timestamp()>1,TIMESTAMP'2001-01-01 10:20:30',0);
 affected rows: 0
-info: Records: 0  Duplicates: 0  Warnings: 0
+info: Records: 0  Duplicates: 0  Warnings: 1
+Warnings:
+Note	1265	Data truncated for column 'b' at row 1
 SELECT * FROM t1;
 a	b
 10	2001-01-01
@@ -1050,7 +1052,9 @@ CREATE TABLE t1 (a INT NOT NULL DEFAULT 0) ENGINE=InnoDB;
 iNSERT INTO t1 VALUES (10);
 ALTER TABLE t1 ADD b TIME NOT NULL DEFAULT if(unix_timestamp()>1,TIMESTAMP'2001-01-01 10:20:30',0);
 affected rows: 0
-info: Records: 0  Duplicates: 0  Warnings: 0
+info: Records: 0  Duplicates: 0  Warnings: 1
+Warnings:
+Note	1265	Data truncated for column 'b' at row 1
 SELECT * FROM t1;
 a	b
 10	10:20:30

sql/sql_table.cc

@@ -9680,9 +9680,17 @@ do_continue:;
     if (use_inplace)
     {
       table->s->frm_image= &frm;
+      enum_check_fields save_count_cuted_fields= thd->count_cuted_fields;
+      /*
+        Set the truncated column values of thd as warning for alter table.
+      */
+      thd->count_cuted_fields= CHECK_FIELD_WARN;
       int res= mysql_inplace_alter_table(thd, table_list, table, altered_table,
                                          &ha_alter_info, inplace_supported,
                                          &target_mdl_request, &alter_ctx);
+
+      thd->count_cuted_fields= save_count_cuted_fields;
+
       my_free(const_cast<uchar*>(frm.str));
 
       if (res)

storage/innobase/row/row0merge.cc

@@ -524,7 +524,9 @@ row_merge_buf_add(
 	DBUG_ENTER("row_merge_buf_add");
 
 	if (buf->n_tuples >= buf->max_tuples) {
-		DBUG_RETURN(0);
+error:
+		n_row_added = 0;
+		goto end;
 	}
 
 	DBUG_EXECUTE_IF(
@@ -845,11 +847,6 @@ end:
         if (vcol_storage.innobase_record)
 		innobase_free_row_for_vcol(&vcol_storage);
 	DBUG_RETURN(n_row_added);
-
-error:
-        if (vcol_storage.innobase_record)
-		innobase_free_row_for_vcol(&vcol_storage);
-        DBUG_RETURN(0);
 }
 
 /*************************************************************//**
@@ -2567,16 +2564,18 @@ write_buffers:
 						new_table, psort_info, row, ext,
 						&doc_id, conv_heap,
 						&err, &v_heap, eval_table, trx)))) {
-					/* An empty buffer should have enough
+                                        /* An empty buffer should have enough
-					room for at least one record. */
+                                        room for at least one record. */
-					ut_error;
+					ut_ad(err == DB_COMPUTE_VALUE_FAILED
+					      || err == DB_OUT_OF_MEMORY
+					      || err == DB_TOO_BIG_RECORD);
+				} else if (err == DB_SUCCESS) {
+					file->n_rec += rows_added;
+					continue;
 				}
 
-				if (err != DB_SUCCESS) {
+				trx->error_key_num = i;
-					break;
+				break;
-				}
-
-				file->n_rec += rows_added;
 			}
 		}