mcsRebuildEM for MariaDB Enterprise ColumnStore
This page is part of MariaDB's Documentation.
The parent of this page is: Command-Line Interfaces for MariaDB Enterprise ColumnStore
Topics on this page:
Overview
MariaDB Enterprise ColumnStore includes the mcsRebuildEM utility, which rebuilds the Extent Map from the contents of the database file system.
Reference material is available for MariaDB Enterprise ColumnStore.
MariaDB Enterprise ColumnStore is included with MariaDB Enterprise Server.
USAGE
The mcsRebuildEM utility should be run from the primary node and requires root or sudo or another user with sufficient privileges for /var/lib/columnstore/* .
The syntax for the mcsRebuildEM utility is:
mcsRebuildEM [OPTIONS]
DETAILS
The mcsRebuildEM utility rebuilds or displays the contents of the Extent Map.
MariaDB Enterprise ColumnStore uses the Extent Map to store metadata about the data stored in each extent. There are certain situations when metadata in the Extent Map can become inconsistent with the extents. In these situations, the Extent Map should be rebuilt.
When no options are provided, the mcsRebuildEM utility rebuilds the Extent Map. It does not check whether the Extent Map is already consistent with the extents. It rebuilds the Extent Map even if the Extent Map is already consistent.
When the -d option is provided, the mcsRebuildEM utility displays what changes it would make to the Extent Map and exits. This option can be used to test the operation without writing changes to disk.
When the -s option is provided, the mcsRebuildEM utility displays the current contents of the Extent Map and exits.
The -h option can be used to view the mcsRebuildEM utility's help output.
The mcsRebuildEM utility is not supported when MariaDB Enterprise ColumnStore is configured to use Object Storage.
Single-Node ColumnStore using Local Storage
With single-node ColumnStore using Local Storage, the mcsRebuildEM utility has the following requirements:
The DB Root directory must be available.
mcsRebuildEM Options by MariaDB Enterprise ColumnStore Version
Choose a version of MariaDB Enterprise ColumnStore to see the options supported by that version: