|PostgreSQL Improves Declarative Partitioning
|Written by Kay Ewbank
|Monday, 02 October 2017
The first release candidate of PostgreSQL 10.0 is now available, with improvements including logical replication and improved query parallelism.
PostgreSQL is an open source database system that was originally created at the University of California, Berkeley. It is now maintained and developed by the PostgreSQL Global Development Group, a coalition of many companies and individual contributors.
The improvements to the new version start with support for logical replication using publish/subscribe. The addition is designed to let you replicate only part of the primary server or write to the secondary if there's a need. The way it works is that on the primary, you create a publication of the tables you want to replicate. On the secondary, you create tables identical to those you're replicating, then set up a subscription to the original tables.
The next improvement is support for declarative table partitioning. This adds commands to create range and list *partitioned* tables and their partitions, though you can't create indexes, row-level triggers, etc. on the partitioned parent table.
The improvements to the parallel query facilities start with the addition of support for parallel merge joins. In the previous release, only hash joins and nested loops can be performed in the parallel portion of a plan. In PostgreSQL 10, merge joins can also be performed in the parallel portion of the plan.
A parallel bitmap heat scan has been added where one process scans the index and builds a data structure in shared memory indicating all of the heap pages that need to be scanned, and then all cooperating processes can perform the heap scan in parallel.
You can now carry out parallel index scans and index-only scans, and a table with an uncorrelated subplan can appear in the parallel portion of the plan.
Other improvements include what the developers say are 'significant' general performance improvements; stronger password authentication based on SCRAM-SHA-256; and improved monitoring and control.
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|Last Updated ( Monday, 02 October 2017 )