EXPLAIN

Returns a formatted description of the Vertica optimizer's plan for executing the specified statement. For detailed information, see EXPLAIN Output Options in the Administrator's Guide.

Syntax

EXPLAIN [/*+ ALLNODES */] [ VERBOSE ] [ JSON ] [ LOCAL ] sql-statement

Parameters

/*+ALLNODES*/	Specifies to create a query plan that assumes all nodes are active.
VERBOSE	Increases the level of detail in the rendered query plan.
JSON	Renders the query plan in JSON format.
LOCAL	On a multi-node database, shows the local query plans assigned to each node, which together comprise the total (global) query plan. If you omit this option, Vertica shows only the global query plan. Local query plan are shown only in DOT language source, which can be rendered in Graphviz.
sql‑statement	A query (SELECT) statement or DML statement—for example, INSERT, UPDATE, COPY, and MERGE.

Privileges

The same privileges required by the specified statement.

Requirements

The following requirements apply to EXPLAIN's ability to produce useful information:

• Reasonably representative statistics of your data must be available. See Collecting Statistics in the Administrator's Guide for details.
• EXPLAIN produces useful output only if projections are available for the queried tables.