Release Notes for MariaDB Xpand 6.0.1


MariaDB Xpand is a distributed SQL database that is part of MariaDB Enterprise. This is the first release in the MariaDB Xpand 6 series.

MariaDB Xpand 6.0.1 was released on 2021-08-26.

This release note pertains to MariaDB Xpand version 6.0.1 and the Xpand Storage Engine packaged with MariaDB Enterprise Server 10.6.4-1.

This release is a Technical Preview. Software in technical preview should not be used for production workloads.

Notable Changes

  • Columnar indexes

    • MariaDB Xpand 6 adds support for Columnar indexes. A single Columnar index can be created on each table, though the index can contain multiple columns.

    • Columnar indexes are best suited for queries that "scan" much or all of a table. This includes queries that perform aggregations on large amounts of data, queries that select a subset of columns from large tables, and queries that perform a full table scan of a fact table. Queries tend to match this pattern in analytical, online-analytical processing (OLAP), and data warehousing workloads.

    • With composite (multi-column) Columnar indexes, filtration is not dependent on column order. If a Columnar index is defined with COLUMNAR INDEX (a, b, c), and the query filters with WHERE b = 1 AND c = 2, the Columnar index can be used to filter the results.

    • To add a Columnar index to an existing table:

      ALTER TABLE hq_sales.invoices
         ADD COLUMNAR INDEX cols (invoice_date, invoice_total);
    • For best performance, MariaDB recommends loading data into the table prior to adding a Columnar index.

    • The cost_read_column system variable is used for costing columnar reads. The default value of cost_read_column in Xpand 5.3 was 0. For deployments upgrading to Xpand 6 from previous versions, the value of cost_read_column should be set to 1.

    • For additional information, see "MariaDB Xpand Columnar Indexes".

  • Ability to statically collect PDs (Probability Distributions)

    • Probability Distributions (PDs) are statistics on data distribution used to generate optimal query execution plans.

    • Prior to this release, all Probability Distributions were dynamic.

    • With this release, Static PDs allow statistics to be gathered on-demand, removing the overhead of continual statistics collection. With Static PDs, statistics can be collected off-peak and persisted indefinitely.

  • Syntax support for ENGINE=XPAND

    • When using the Xpand Storage Engine Topology, CREATE TABLE .. ENGINE=XPAND is specified to select Xpand rather than the default storage engine.

    • With this release, when using the Xpand Performance Topology, CREATE TABLE .. ENGINE=XPAND and ALTER TABLE .. ENGINE=XPAND are accepted syntax.

    • Prior to this release, when using the Xpand Performance Topology, CREATE TABLE .. ENGINE=XPAND and ALTER TABLE .. ENGINE=XPAND generate a syntax error.

  • Support for sha256_password without TLS using sha256_password_private_key_path and sha256_password_public_key_path.

  • Path changes

    • /etc/xpand replaces /etc/clustrix

    • /etc/xpand/xpdnode.conf replaces clxnode.conf

    • uninstall_xpand replaces uninstall_clustrix

    • Alerter config moves to /etc/xpand

    • Upgrade messages now reference Xpand

  • Updated list of recommended Amazon AWS EC2 instance types

  • OOM protection applies only when running as root

  • clx_import will not re-slice ALLNODES tables

  • clx_import can prompt for password

    • Prior to this release, clx_import required password to be specified on the command-line.

    • With this release, clx_import prompts for password when not specified on the command-line.