Chalk SQL Statements

Chalk SQL supports a focused set of SQL statements built around reading and introspecting data across your Chalk environment. Each page in this section documents one statement in detail, including its clauses, restrictions, and examples.

Statement	Description
SELECT	Query data from data sources, the offline store, and the Chalk catalog
DESCRIBE / SHOW	Inspect the schema of a table or query, or list available tables
EXPLAIN	Show the physical plan for a statement, optionally with execution statistics
COPY ... TO	Write the result of a query to Parquet, CSV, or Iceberg files

The Chalk SQL function reference documents the scalar functions available in Chalk SQL expressions. For the complete inventory, including aggregate and table-valued functions, query "chalk.information_schema.functions", whose is_aggregate and is_table_valued columns say which kind each name is.

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General rules

• One statement per query. Each Chalk SQL request executes exactly one statement. Submitting multiple ;-separated statements returns an error.
• Read-only. Chalk SQL is a read-only interface over the Chalk catalog and your configured data sources. The one statement that produces output outside of the query response is COPY ... TO, which exports query results to files without modifying any source.
• Supported syntax. Each statement page documents the syntax and restrictions that Chalk SQL supports. For expression syntax, see the Chalk SQL function reference.
• Fully qualify catalog tables. Tables in the Chalk catalog and in configured data sources are referenced by a quoted, fully-qualified "catalog.schema.table" name, for example SELECT * FROM "chalk.online_store.keys". See Referencing the Chalk Catalog.