While the following mechanisms work automatically without your intervention, it might be interesting to know what the Exasol database does for you under the hood.

Optimizer Statistics Gathering

The Exasol optimizer works cost based using statistics that inform it about object attributes like size and number of rows. These statistics are automatically gathered after each DML statement without any administrative effort.

Index Creation, Maintenance, and Deletion

Indexes that are required for JOIN operations are automatically created and subsequently maintained upon DML that modifies indexed tables. If indexes are not used for more than five weeks, they are automatically dropped.

Table Reorganization

A DELETE operation will initially just mark rows as deleted within a table until more than 25% of rows are marked as deleted. Then the table is automatically reorganized while indexes on that table are rebuilt automatically as well.

More information about automation can be found in Technical Whitepaper A Drill-Down into Exasol.

Query Cache

Exasol uses a Query Cache to store the result of statements in memory. If a statement runs repeatedly and produces deterministic results, Exasol shows the cached result again instead of accessing data blocks to fetch the result.

The feature is enabled by default. However, you can disable the feature using ALTER SESSION or ALTER SYSTEM statements. For example, ALTER SESSION SET query_cache='OFF';