Persistent Queries¶

Persistent Queries (per PersistentQueryType) can be the following queries:

• CREATE_SOURCE
• CREATE STREAM AS SELECT
• CREATE TABLE AS SELECT
• INSERT INTO

When Analyzer is requested to analyze a query it creates a Visitor with a flag to indicate whether the sink is defined or not for persistent queries.

CREATE_SOURCE¶

CREATE_SOURCEs don't write to a topic (so EngineExecutor does not have to check for read-only topics the other query types could attempt to write to).

It is forbidden to terminate CREATE_SOURCE queries when linked to a source table (and ValidatedCommandFactory throws a KsqlStatementException):

Cannot terminate query '[queryId]' because it is linked to a source table.

EngineExecutor will not execute CREATE_SOURCE plans when ksql.source.table.materialization.enabled is disabled and prints out the following INFO message to the logs instead:

Source table query '[statementText]' won't be materialized because 'ksql.source.table.materialization.enabled' is disabled.

CREATE_SOURCE is used when:

• KsqlPlanV1 is requested for the getPersistentQueryType (with the queryPlan and the ddlCommand specified as a source CreateTableCommand)
• QueryBuilder is requested to buildPersistentQueryInDedicatedRuntime and buildPersistentQueryInSharedRuntime
• QueryRegistryImpl is requested to registerPersistentQuery and unregisterQuery