What is a smart table replication and how can the replication border be modified?
General information on smart table replication
Replicates are used "on-the-fly" for local joins if a table is "small" regarding the threshold.
A replicated table accesses data directly from other nodes' database memories and keeps a local copy in its own DBRAM.
If a replicated table is modified, only changed data is reloaded into database memories of other nodes.
Modified tables and subselects cannot be used with smart table replication. Table replication border does not apply to those.
💡 Using large replicated tables might cause decreased performance. Queries with expensive table scans (filter expressions) or between / cross joins may fall into this category.
Soft replication border
A table will be replicated if none of the thresholds below are reached. The table size threshold refers to the RAW_OBJECT_SIZE like in EXA_*_OBJECT_SIZES. The replication borders can be modified throughextra database parametersin the web interface:
-soft_replicationborder_in_numrows=<numrows> [default is 100000 rows]
-soft_replicationborder_in_kb=<kb> [default is 1000000 -> 1GB]