Session settings

Table of contents

Session settings only apply to the currently connected client session.

Usage

To configure a modifiable session setting, use SET, for example:

SET search_path TO myschema, doc;

To retrieve the current value of a session setting, use SHOW eg:

SHOW search_path;

Besides using SHOW, it is also possible to use the current_setting scalar function.

Supported session settings

search_path
Default: pg_catalog, doc
Modifiable: yes

The list of schemas to be searched when a relation is referenced without a schema.

CrateDB will try to resolve an unqualified relation name against the configured search_path by iterating over the configured schemas in the order they were declared. The first matching relation in the search_path is used. CrateDB will report an error if there is no match.

Note

This setting mirrors the PostgreSQL search_path setting.

Some PostgreSQL clients require access to various tables in the pg_catalog schema. Usually, this is to extract information about built-in data types or functions.

CrateDB implements the system pg_catalog schema and it automatically includes it in the search_path before the configured schemas, unless it is already explicitly in the schema configuration.

enable_hashjoin
Default: true
Modifiable: yes

An experimental setting which enables CrateDB to consider whether a Join operation should be evaluated using the HashJoin implementation instead of the Nested-Loops implementation.

Note

It is not always possible or efficient to use the HashJoin implementation. Having this setting enabled, will only add the option of considering it, it will not guaranty it. See also the available join algorithms for more insights on this topic.

max_index_keys
Default: 32
Modifiable: no

Shows the maximum number of index keys.

Note

The session setting has no effect in CrateDB and exists for compatibility with PostgreSQL.

server_version_num
Default: 100500
Modifiable: no

Shows the emulated PostgreSQL server version.

server_version
Default: 10.5
Modifiable: no

Shows the emulated PostgreSQL server version.

optimizer
Default: true
Modifiable: yes

This setting indicates whether a query optimizer rule is activated. The name of the query optimizer rule has to be provided as a suffix as part of the setting e.g. SET optimizer_rewrite_collect_to_get = false.

Note

The optimizer setting is for advanced use only and can significantly impact the performance behavior of the queries.

Warning

Experimental session settings might be removed in the future even in minor feature releases.