Temporal tables should be row partitioned to improve query performance. Partitioning can logically group the table rows into current and history, open and closed rows. For bitemporal tables, queries of current and open rows are directed automatically to the partition containing these rows.
Example: Row Partitioning an ANSI Valid-Time Table
To row partition a valid-time table, use the following PARTITION BY clause.
CREATE MULTISET TABLE employee_bitemp (
eid INTEGER NOT NULL,
ename VARCHAR(5),
deptno INTEGER NOT NULL,
terms VARCHAR(5),
job_start DATE NOT NULL,
job_end DATE NOT NULL,
PERIOD FOR job_dur (job_start,job_end) AS VALIDTIME,
sys_start TIMESTAMP(6) WITH TIME ZONE NOT NULL
GENERATED ALWAYS AS ROW START,
sys_end TIMESTAMP(6) WITH TIME ZONE NOT NULL
GENERATED ALWAYS AS ROW END,
PERIOD FOR SYSTEM_TIME(sys_start,sys_end)
)
PRIMARY INDEX (eid)
PARTITION BY CASE_N (
(END(job_dur) >= CURRENT_DATE AT INTERVAL -'12:59' HOUR TO MINUTE)
AND END(SYSTEM_TIME) >= CURRENT_TIMESTAMP,
END(job_dur) < CURRENT_DATE AT INTERVAL -'12:59' HOUR TO MINUTE
AND END(SYSTEM_TIME) >= CURRENT_TIMESTAMP,
END(SYSTEM_TIME) < CURRENT_TIMESTAMP
)
WITH SYSTEM VERSIONING;
Notes
- The partitioning expression could have used sys_end instead of END(SYSTEM_TIME) and job_end instead of END(job_dur).
- WITH SYSTEM VERSIONING must be the last clause in the CREATE TABLE statement.
Maintaining a Current Partition
As time passes, and current rows become history rows, you should periodically use the ALTER TABLE TO CURRENT statement to transition history rows out of the current partition into the history partition. ALTER TABLE TO CURRENT resolves the partitioning expressions again, transitioning rows to their appropriate partitions per the updated partitioning expressions. For example:
ALTER TABLE temporal_table_name TO CURRENT;
This statement also updates any system-defined join indexes that were automatically created for primary key and unique constraints defined on the table.