When we create a materialized view for multiple tables, users may not figure out the partition rule for the materialized view, because the query result can be too complex. If the query result doesn't match one of the partition rules, the insertion will fail.
We can resolve this issue by mapping the partition rule of base table to the materialized view. As a result, users don't need specify the partition rules and query results are all valid because they are retrieved from the partitions of the base table.
## Use case
mysql> CREATE TABLE t1 (pk INT NOT NULL, v1 INT SUM) PARTITION BY RANGE(pk) (
-> PARTITION p1 VALUES LESS THAN ('10'),
-> PARTITION p2 VALUES LESS THAN ('90')
-> )
-> DISTRIBUTED BY HASH(pk)
-> PROPERTIES ('replication_num' = '1');
Query OK, 0 rows affected (0.04 sec)
mysql> CREATE TABLE t2 (pk INT NOT NULL, v2 INT SUM) PARTITION BY LIST(pk) (
-> PARTITION odd VALUES IN ('10', '30', '50', '70', '90'),
-> PARTITION even VALUES IN ('20', '40', '60', '80')
-> )
-> DISTRIBUTED BY HASH(pk)
-> PROPERTIES ('replication_num' = '1');
Query OK, 0 rows affected (0.02 sec)
mysql> CREATE MATERIALIZED VIEW mv BUILD IMMEDIATE REFRESH COMPLETE
-> KEY (mpk) PARTITION BY (t1.pk) DISTRIBUTED BY HASH(mpk) PROPERTIES ('replication_num' = '1')
-> AS SELECT t1.pk AS mpk, v1, v2 FROM t1, t2 WHERE t1.pk = t2.pk;
Query OK, 0 rows affected (0.10 sec)
mysql> SHOW CREATE TABLE mv;
+-------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Materialized View | Create Materialized View |
+-------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| mv | CREATE MATERIALIZED VIEW `mv`
BUILD IMMEDIATE REFRESH COMPLETE ON DEMAND
KEY(`mpk`)
PARTITION BY RANGE(`mpk`)
(PARTITION p1 VALUES [("-2147483648"), ("10")),
PARTITION p2 VALUES [("10"), ("90")))
DISTRIBUTED BY HASH(`mpk`) BUCKETS 10
PROPERTIES (
"replication_allocation" = "tag.location.default: 1",
"in_memory" = "false",
"storage_format" = "V2",
"disable_auto_compaction" = "false"
)
AS SELECT `t1`.`pk` AS `mpk`, `v1` AS `v1`, `v2` AS `v2` FROM `default_cluster:dev`.`t1` , `default_cluster:dev`.`t2` WHERE `t1`.`pk` = `t2`.`pk`; |
+-------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
ef1bb9819a