HeatWave Release Notes
After tables are loaded into HeatWave, data changes are
automatically propagated from InnoDB tables
on the MySQL DB System to their counterpart tables in the
HeatWave Cluster.
DML operations (INSERT,
UPDATE,
DELETE) on the MySQL DB System
do not wait for changes to be propagated to the HeatWave Cluster;
that is, DML operations on the MySQL DB System are not delayed
by HeatWave change propagation.
Data changes on the MySQL DB System node are propagated to HeatWave in batch transactions. Change propagation is initiated as follows:
Every 200ms.
When the change propagation buffer reaches its 64MB capacity.
When data updated by DML operations on the MySQL DB System are read by a subsequent HeatWave query.
A change propagation failure can cause tables in HeatWave to become stale, and queries that access stale tables are not offloaded to HeatWave for processing.
Tables that have become stale due to change propagation failures resulting from out-of-code errors are automatically reloaded. A check for stale tables is performed periodically when the HeatWave Cluster is idle.
If change propagation failure has occurred for some other reason causing a table to become stale, you must unload and reload the table manually to restart change propagation for the table. See Section 2.5.1, “Unloading Tables”, and Section 2.2, “Loading Data to HeatWave”.
To check if change propagation is enabled globally, query the
rapid_change_propagation_status
variable:
mysql> SELECT VARIABLE_VALUE
FROM performance_schema.global_status
WHERE VARIABLE_NAME = 'rapid_change_propagation_status';
+----------------+
| VARIABLE_VALUE |
+----------------+
| ON |
+----------------+
To check if change propagation is enabled for individual
tables, query the POOL_TYPE data in HeatWave
Performance Schema tables.
RAPID_LOAD_POOL_TRANSACTIONAL indicates
that change propagation is enabled for the table.
RAPID_LOAD_POOL_SNAPSHOT indicates that
change propagation is disabled.
mysql> SELECT NAME, POOL_TYPE
FROM rpd_tables,rpd_table_id
WHERE rpd_tables.ID = rpd_table_id.ID AND SCHEMA_NAME LIKE 'tpch';
+---------------+-------------------------------+
| NAME | POOL_TYPE |
+---------------+-------------------------------+
| tpch.orders | RAPID_LOAD_POOL_TRANSACTIONAL |
| tpch.region | RAPID_LOAD_POOL_TRANSACTIONAL |
| tpch.lineitem | RAPID_LOAD_POOL_TRANSACTIONAL |
| tpch.supplier | RAPID_LOAD_POOL_TRANSACTIONAL |
| tpch.partsupp | RAPID_LOAD_POOL_TRANSACTIONAL |
| tpch.part | RAPID_LOAD_POOL_TRANSACTIONAL |
| tpch.customer | RAPID_LOAD_POOL_TRANSACTIONAL |
+---------------+-------------------------------+