Configuration Settings

ZomboDB provides a number of configuration settings that affect how it operates.

postgresql.conf-only settings

The below settings can only be set in postgresql.conf and require a Postgres configuration reload (or server restart) to be changed.

zdb.default_elasticsearch_url

Type: string
Default: null

Defines the default URL for your Elasticsearch cluster so you can elite setting it on every index during CREATE INDEX. The value used must end with a forward slash (/).

Example: zdb.default_elasticsearch_url = 'http://es.cluster.ip:9200/'

zdb.default_replicas

Type: integer
Default: 0

Defines the number of replicas all new indices should have. Changing this value does not propagate to existing indices.

Session-level "GUC" settings

The below settings may be set in postgresql.conf, but they can also be changed per session/transaction using Postgres SET key TO value command;

zdb.default_row_estimate

Type: integer
Default: 2500
Range: [-1, INT_MAX]

ZomboDB needs to provide Postgres with an estimate of the number of rows Elasticsearch will return for any given query. 2500 is a sensible default estimate that generally convinces Postgres to use an IndexScan plan. Setting this to -1 will cause ZomboDB to execute an Elasticsearch _count request for every query to return the exact number.

Also note that you can change this parameter at query-time (see dsl.row_estimate()).

zdb.ignore_visibility

Type: boolean
Default: false

ZomboDB applies MVCC visibility rules to all queries and aggregate functions. Setting this to true instructs ZomboDB to not do that, which means aggregate functions (such as zdb.terms()) will see dead rows, aborted rows, and in-flight rows. Generally, this should only be used for debugging.

zdb.log_level

Type: enum
Default: DEBUG1
Possible Values: DEBUG2, DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1, INFO, NOTICE, WARNING, LOG

The Postgres log level ZomboDB sends all of its log messages.

zdb.enable_search_accelerator

Type: boolean
Default: false

Indicates if you have the ZomboDB Search Accelerator installed on your backing Elasticsearch cluster.

If you do, ZomboDB is able to highly optimize certain queries, especially those that perform cross-index joins.