![]() ![]() In the hash partitioned case, the hash of each column value that is part of the partition key is individually calculated and then combined to get a single 64-bit hash value. Note that if any of the partition key column values is NULL then it can only be routed to the default partition if it exists else it throws an error. On the same grounds, rows with value (100, 50) or (101, 10) will not be accepted in the said partition. The partition key value (100, 49) would also be accepted because the first column value is equal to the upper bound specified and so the second column is considered here and it satisfies the restriction 0 to 50. This would accept a row with the partition key value (0, 100) because the value of the first column satisfies the partition bound of the first column which is 0 to 100 and in this case the second column is not considered. If the partition key value is equal to the upper bound of that column then the next column will be considered.Ĭonsider a partition with bound (0,0) to (100, 50). In a single partitioned table with bound of 0 to 100, rows with partition key value 0 will be permitted in the partition but rows with value 100 will not.įor a multi-column range partition, the row comparison operator is used for tuple routing which means the columns are compared left-to-right, stopping at first unequal value pair. In the range partitioned table, the lower bound is included in the table but the upper bound is excluded. This section explains how the tuple routing takes place for the range and hash multi-column partition key. The partitioned parent table will not store any rows but routes all the inserted rows to one of the partitions based on the value of the partition key. Or ALTER TABLE tbl_hash ATTACH PARTITION h1įOR VALUES FROM (WITH (MODULUS 100, REMAINDER 20) CREATE TABLE p1 PARTITION OF tbl_hashįOR VALUES WITH (MODULUS 100, REMAINDER 20) When we mention the partition bounds for a partition of a multicolumn hash partitioned table, we need to specify only one bound irrespective of the number of columns used. CREATE TABLE r2 PARTITION OF tbl_rangeįOR VALUES FROM (900, MINVALUE, MINVALUE) TO (1020, 200, 200) ĪLTER TABLE tbl_range ATTACH PARTITION r3įOR VALUES FROM (1, 110, 50) TO (MAXVALUE, MAXVALUE, MAXVALUE) Please note that if the unbounded value - MINVALUE or MAXVALUE - is used for one of the columns, then all the subsequent columns should also use the same unbounded value. The tuple routing section explains how these bounds work for the partition. Or ALTER TABLE tbl_range ATTACH PARTITION r1 CREATE TABLE p1 PARTITION OF tbl_rangeįOR VALUES FROM (1, 110, 50) TO (20, 200, 200) When we mention the partition bounds for a partition of a multicolumn range partitioned table, we need to specify the bound for each of the columns of the partition key in the CREATE TABLE. CREATE TABLE tbl_range (id int, col1 int, col2 int, col3 int)ĬREATE TABLE tbl_hash (id int, col1 int, col2 int, col3 int) ![]() To create a multi-column partition, when defining the partition key in the CREATE TABLE command, state the columns as a comma-separated list. Range partitioning was introduced in PostgreSQL10 and hash partitioning was added in PostgreSQL 11. ![]() Currently multi-column partitioning is possible only for range and hash type. ![]() Multi-column partitioning allows us to specify more than one column as a partition key. This article covers how to create a multi-column partitioned table and how pruning occurs in such cases. ![]()
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