PolarDB:Usage

Create a DLM policy

In the following example, a partitioned table named sales is created. The table uses the order_time column as the partition key and adopts interval partitioning. An interval policy and a DLM policy are defined for the table.

• Interval policy: When data inserted into the table falls outside the partitioning interval of one year, a new partition is automatically created.

• DLM policy: When the number of partitions in the table exceeds 3, the DLM policy is executed to transfer previous partitions to OSS.

1. Create a table named sales.

   CREATE TABLE `sales` (
     `id` int DEFAULT NULL,
     `name` varchar(20) DEFAULT NULL,
     `order_time` datetime NOT NULL,
      PRIMARY KEY (`order_time`)
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
   PARTITION BY RANGE  COLUMNS(order_time) INTERVAL(YEAR, 1)
   (PARTITION p20200101000000 VALUES LESS THAN ('2020-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION p20210101000000 VALUES LESS THAN ('2021-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION p20220101000000 VALUES LESS THAN ('2022-01-01 00:00:00') ENGINE = InnoDB)
   DLM ADD POLICY policy_part2part TIER TO PARTITION ENGINE=CSV STORAGE=OSS READ ONLY ON (PARTITIONS OVER 3);

   The DLM policy of the table is named policy_part2part. When the number of partitions in the table exceeds 3, previous partitions are transferred to OSS.

2. View DLM policies in the mysql.dlm_policies table.

   SELECT * FROM mysql.dlm_policies\G

   Sample result:

   *************************** 1. row ***************************
                      Id: 2
            Table_schema: test
              Table_name: sales
             Policy_name: policy_part2part
             Policy_type: PARTITION
            Archive_type: PARTITION COUNT
            Storage_mode: READ ONLY
          Storage_engine: CSV
           Storage_media: OSS
     Storage_schema_name: NULL
      Storage_table_name: NULL
         Data_compressed: OFF
    Compressed_algorithm: NULL
                 Enabled: ENABLED
         Priority_number: 10300
   Tier_partition_number: 3
          Tier_condition: NULL
              Extra_info: null
                 Comment: NULL
   1 row in set (0.03 sec)

3. Use the proc_batch_insert stored procedure to insert test data into the sales table and trigger the interval policy to create new partitions.

   CALL proc_batch_insert(1, 3000, 'sales');

   The following results indicate that the data is inserted:

   Query OK, 1 row affected, 1 warning (0.99 sec)

4. To view the schema of the sales table, execute the following statement:

   SHOW CREATE TABLE sales \G

   Sample result:

   *************************** 1. row ***************************
          Table: sales
   Create Table: CREATE TABLE `sales` (
     `id` int(11) DEFAULT NULL,
     `name` varchar(20) DEFAULT NULL,
     `order_time` datetime DEFAULT NULL,
      PRIMARY KEY (`order_time`)
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
   /*!50500 PARTITION BY RANGE  COLUMNS(order_time) */ /*!99990 800020200 INTERVAL(YEAR, 1) */
   /*!50500 (PARTITION p20200101000000 VALUES LESS THAN ('2020-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION p20210101000000 VALUES LESS THAN ('2021-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION p20220101000000 VALUES LESS THAN ('2022-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20230101000000 VALUES LESS THAN ('2023-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20240101000000 VALUES LESS THAN ('2024-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20250101000000 VALUES LESS THAN ('2025-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20260101000000 VALUES LESS THAN ('2026-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20270101000000 VALUES LESS THAN ('2027-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20280101000000 VALUES LESS THAN ('2028-01-01 00:00:00') ENGINE = InnoDB) */
   1 row in set (0.03 sec)

Execute the DLM policy

1. Execute the following statement to execute the DLM policy:

   CALL dbms_dlm.execute_all_dlm_policies();

2. View the execution records of the DLM policy in the mysql.dlm_progress table.

   SELECT * FROM mysql.dlm_progress \G

   Sample result:

   *************************** 1. row ***************************
                     Id: 4
           Table_schema: test
             Table_name: sales
            Policy_name: policy_part2part
            Policy_type: PARTITION
         Archive_option: PARTITIONS OVER 3
         Storage_engine: CSV
          Storage_media: OSS
        Data_compressed: OFF
   Compressed_algorithm: NULL
     Archive_partitions: p20200101000000, p20210101000000, p20220101000000, _p20230101000000, _p20240101000000, _p20250101000000
          Archive_stage: ARCHIVE_COMPLETE
     Archive_percentage: 100
     Archived_file_info: null
             Start_time: 2023-09-11 18:04:39
               End_time: 2023-09-11 18:04:40
             Extra_info: null
   1 row in set (0.02 sec)

3. To view the schema of the sales table, execute the following statement:

   SHOW CREATE TABLE sales \G

   Sample result:

   *************************** 1. row ***************************
          Table: sales
   Create Table: CREATE TABLE `sales` (
     `id` int(11) DEFAULT NULL,
     `name` varchar(20) DEFAULT NULL,
     `order_time` datetime DEFAULT NULL,
      PRIMARY KEY (`order_time`)
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci CONNECTION='default_oss_server'
   /*!99990 800020205 PARTITION BY RANGE  COLUMNS(order_time) */ /*!99990 800020200 INTERVAL(YEAR, 1) */
   /*!99990 800020205 (PARTITION p20200101000000 VALUES LESS THAN ('2020-01-01 00:00:00') ENGINE = CSV,
    PARTITION p20210101000000 VALUES LESS THAN ('2021-01-01 00:00:00') ENGINE = CSV,
    PARTITION p20220101000000 VALUES LESS THAN ('2022-01-01 00:00:00') ENGINE = CSV,
    PARTITION _p20230101000000 VALUES LESS THAN ('2023-01-01 00:00:00') ENGINE = CSV,
    PARTITION _p20240101000000 VALUES LESS THAN ('2024-01-01 00:00:00') ENGINE = CSV,
    PARTITION _p20250101000000 VALUES LESS THAN ('2025-01-01 00:00:00') ENGINE = CSV,
    PARTITION _p20260101000000 VALUES LESS THAN ('2026-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20270101000000 VALUES LESS THAN ('2027-01-01 00:00:00') ENGINE = InnoDB,
    PARTITION _p20280101000000 VALUES LESS THAN ('2028-01-01 00:00:00') ENGINE = InnoDB) */
   1 row in set (0.03 sec)

   The preceding results show that the p20200101000000, p20210101000000, p20220101000000, _p20230101000000, _p20240101000000, and _p20250101000000 partitions in the sales table are transferred to OSS. Only the _p20260101000000, _p20270101000000, and _p20280101000000 partitions that store hot data in the table are retained in InnoDB. The sales table becomes a hybrid partitioned table. For information about how to query data in a hybrid partitioned table, see Query data in a hybrid partitioned table.