|Partitioning Tables / Creating Partitioned Tables|
Use the REDUNDANCY clause to specify a number of redundant copies of a table for each partition to maintain.
CREATE TABLE COUNTRIES ( COUNTRY VARCHAR(26) NOT NULL, COUNTRY_ISO_CODE CHAR(2) NOT PRIMARY KEY, REGION VARCHAR(26), ) REDUNDANCY 1
GemFire XD attempts to place copies of the same bucket onto hosts that have different IP addresses if possible, to protect against machine failure. However, if there is only one machine available GemFire XD places multiple copies on that machine. Setting the enforce-unique-host boot property prevents GemFire XD from ever placing multiple copies on the same machine.
Set the redundancy-zone boot property to ensure that GemFire XD places redundant copies on specific zones that you define. For example, to ensure that redundant copies are placed on different racks, set the redundancy-zone for each machine to the logical name of the rack on which the machine runs.
If the primary and secondary buckets for a partition are unavailable, then queries to the table can fail. For a persistent table, queries involving missing buckets fail with a PartitionOfflineException. Queries across the entire table would also fail. Queries to non-persistent tables with missing partitions can return empty results.