EXPLAIN MATERIALIZED VIEW

Applies to: Databricks SQL Databricks Runtime

Provides information about whether a query can be incrementalized when being refreshed for a materialized view.

To learn about materialized view incrementalization, see Incremental refresh for materialized views.

重要

EXPLAIN MATERIALIZED VIEW confirms structural eligibility for incrementalization. It does not guarantee an incremental refresh will be executed when using the AUTO policy. In that mode, the cost model still chooses a full recompute at runtime if factors like changeset size make a full refresh cheaper. The REFRESH POLICY INCREMENTAL and REFRESH POLICY INCREMENTAL STRICT policies override this cost model decision.

Syntax

EXPLAIN MATERIALIZED VIEW FOR query

Parameters

• query

  A SQL query for a materialized view to be explained.

Examples

SQL

EXPLAIN MATERIALIZED VIEW FOR select k, sum(v) from source.src_schema.table group by k;

+----------------------------------------------------+
|                                                plan|
+----------------------------------------------------+
| == Physical Plan ==
 *(2) HashAggregate(keys=[k#33], functions=[sum(cast(v#34 as bigint))])
 +- Exchange hashpartitioning(k#33, 200), true, [id=#59]
    +- *(1) HashAggregate(keys=[k#33], functions=[partial_sum(cast(v#34 as bigint))])
       +- *(1) LocalTableScan [k#33, v#34]
|
+----------------------------------------------------