MemSQL 2.1 Release Notes¶
Distributed Joins Across Foreign Shard Keys¶
MemSQL 2.1 introduces foreign shard keys: a new concept that enables you to efficiently join distributed tables together. The FOREIGN SHARD KEY syntax lets you to define relationships between distributed tables when you create them and then leverage these relationships to join them together.
Non-unique Shard Keys¶
Before version 2.1, MemSQL only supported sharding a distributed table by its primary key. Along with foreign shard keys, MemSQL now also supports non-unique shard keys. See Distributed SQL for details on how to define shard keys and leverage them in your SQL queries.
MemSQL now supports the LOAD DATA command for quickly loading data stored in a text file into a table. You can run this command on a MemSQL aggregator to bulk load data into the cluster. This command supports data stored as CSV, TSV, and several other delimited/escaped data storage formats.
In the past, when a leaf node became unavailable, MemSQL would remove it from the system. MemSQL now tracks failed leaf nodes with states and exposes commands that help you manage these node states. MemSQL also supports recovering data when you bring a leaf node back up via the ATTACH LEAF command. See Administering a Cluster for a step-by-step demonstration of the various states and how to recover the cluster.
Every download of MemSQL now also includes a link to an RPM file that you can use to install MemSQL on RPM-based Linux distributions including CentOS, RedHat, and Amazon’s Linux AMI. The RPM link is part of the download email you receive when you download the software. MemSQL’s RPM supports a standard set of commands (start, stop, restart, and status) as well as a check-system command to validate the underlying system. Furthermore, if you wish to upgrade MemSQL, the RPM will automatically detect and upgrade a previously installed MemSQL, preserving your data and configuration in the process.
To install MemSQL from the RPM file, simply run
$ sudo yum install --nogpgcheck memsql-2.1-1.x86_64.rpm