Help Center/ GaussDB/ Feature Guide(Distributed_3.x)/ Partitioned Table/ Partitioned Table O&M Management/ ALTER TABLE ENABLE/DISABLE ROW MOVEMENT
Updated on 2024-05-20 GMT+08:00
View PDF
Share

ALTER TABLE ENABLE/DISABLE ROW MOVEMENT

You can run this command to enable or disable row movement for a partitioned table.

When row migration is enabled, data in a partition can be migrated to another partition through an UPDATE operation. When row migration is disabled, if such an UPDATE operation occurs, a service error is reported.

If you are not allowed to update the column where the partition key is located, you are advised to disable row migration.

For example, if you create a list partitioned table and enable row migration, you can update the column where the partition key is located across partitions. If you disable row migration, an error is reported when you update the column where the partition key is located across partitions. 
CREATE TABLE list_sales
(
    product_id     INT4 NOT NULL,
    customer_id    INT4 PRIMARY KEY,
    time_id        DATE,
    channel_id     CHAR(1),
    type_id        INT4,
    quantity_sold  NUMERIC(3),
    amount_sold    NUMERIC(10,2)
)
PARTITION BY LIST (channel_id)
(
    PARTITION channel1 VALUES ('0', '1', '2'),
    PARTITION channel2 VALUES ('3', '4', '5'),
    PARTITION channel3 VALUES ('6', '7'),
    PARTITION channel4 VALUES ('8', '9')
) ENABLE ROW MOVEMENT;
INSERT INTO list_sales VALUES (153241,65143129,'2021-05-07','0',864134,89,34);
-- The cross-partition update is successful, and data is migrated from partition channel1 to partition channel2.
UPDATE list_sales SET channel_id = '3' WHERE channel_id = '0';
-- Disable row migration for the partitioned table.
ALTER TABLE list_sales DISABLE ROW MOVEMENT;
-- The cross-partition update fails, and an error is reported: fail to update partitioned table "list_sales".
UPDATE list_sales SET channel_id = '0' WHERE channel_id = '3';
-- The update in the partition is still successful.
UPDATE list_sales SET channel_id = '4' WHERE channel_id = '3';