cdc: EXCHANGE PARTITION dropped the WITHOUT VALIDATION clause

[kennytm]

What did you do?

create a TiDB → TiCDC → TiDB changefeed and execute the following in upstream:

USE test;

CREATE TABLE employees (
    id INT NOT NULL ,
    store_id INT NOT NULL primary key
) PARTITION BY RANGE (store_id) (
    PARTITION p0 VALUES LESS THAN (6),
    PARTITION p1 VALUES LESS THAN (11),
    PARTITION p2 VALUES LESS THAN (16),
    PARTITION p3 VALUES LESS THAN (21)
);

CREATE TABLE employees_temp (
    id INT NOT NULL ,
    store_id INT NOT NULL primary key
);

insert into employees values(1,1);
insert into employees values(8,8);
insert into employees_temp values(16,8);
insert into employees_temp values(17,17);

ALTER TABLE employees EXCHANGE PARTITION p0 WITH TABLE employees_temp without VALIDATION;

What did you expect to see?

The DDL is sync to the downstream TiDB correctly.

What did you see instead?

The changefeed is stuck. TiCDC has rewritten the DDL which stripped out the WITHOUT VALIDATION option

ALTER TABLE `test`.`employees` EXCHANGE PARTITION `p0` WITH TABLE `test`.`employees_temp`

which caused the [ddl:1737]Found a row that does not match the partition unretryable error

Versions of the cluster

Upstream TiDB cluster version (execute SELECT tidb_version(); in a MySQL client):

v6.5.8

Upstream TiKV version (execute tikv-server --version):

v6.5.8

TiCDC version (execute cdc version):

v6.5.8

[kennytm]

The DDL is constructed in:

tiflow/cdc/model/sink.go

Lines 1052 to 1063 in c178273

	case model.ActionExchangeTablePartition:
	// Parse idx of partition name from query.
	upperQuery := strings.ToUpper(job.Query)
	idx1 := strings.Index(upperQuery, "EXCHANGE PARTITION") + len("EXCHANGE PARTITION")
	idx2 := strings.Index(upperQuery, "WITH TABLE")
	// Note that partition name should be parsed from original query, not the upperQuery.
	partName := strings.TrimSpace(job.Query[idx1:idx2])
	// The tableInfo is the partition table, preTableInfo is non partition table.
	d.Query = fmt.Sprintf("ALTER TABLE `%s`.`%s` EXCHANGE PARTITION `%s` WITH TABLE `%s`.`%s`",
	tableInfo.TableName.Schema, tableInfo.TableName.Table, partName,
	preTableInfo.TableName.Schema, preTableInfo.TableName.Table)

which did not check if the query contained the "WITHOUT VALIDATION" clause

I also question the method to extract the part name from the SQL. Because running this:

ALTER TABLE employees EXCHANGE   /*lol*/   PARTITION p0 WITH    /*rofl*/   TABLE employees_temp without VALIDATION;

will immediately crash TiCDC.

[fubinzh]

/severity major

[seiya-annie]

/found customer