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REFRESH EXTERNAL TABLE

Description​

Updates metadata cached in StarRocks. The metadata is from tables in data lakes. This statement is used in the following scenarios:

  • External table: When using a Hive external table or Hudi external table to query data in Apache Hive™ or Apache Hudi, you can execute this statement to update the metadata of a Hive table or Hudi table cached in StarRocks.
  • External catalog: When using a Hive catalog, Hudi catalog, or Delta Lake catalog to query data in the corresponding data source, you can execute this statement to update the metadata cached in StarRocks.

Basic concepts​

  • Hive external table: is created and stored in StarRocks. You can use it to query Hive data.
  • Hudi external table: is created and stored in StarRocks. You can use it to query Hudi data.
  • Hive table: is created and stored in Hive.
  • Hudi table: is created and stored in Hudi.

Syntaxes and parameters​

The following describes the syntaxes and parameters based on different cases:

  • External table

    REFRESH EXTERNAL TABLE table_name 
    [PARTITION ('partition_name', ...)]
    ParameterRequiredDescription
    table_nameYesThe name of a Hive external table or Hudi external table.
    partition_nameNoThe names of the partitions of a Hive table or Hudi table. Specifying this parameter updates the metadata of the partitions of the Hive table and Hudi table cached in StarRocks.

  • External catalog

    REFRESH EXTERNAL TABLE [external_catalog.][db_name.]table_name
    [PARTITION ('partition_name', ...)]
    ParameterRequiredDescription
    external_catalogNoThe name of the external catalog, which supports Hive, Hudi, Delta Lake catalogs.
    db_nameNoThe name of the database where the destination table resides.
    table_nameYesThe name of the table.
    partition_nameNoThe names of the partitions. Specifying this parameter updates the metadata of the partitions of the destination table cached in StarRocks.

Usage notes​

Only users who have the ALTER_PRIV privilege can execute this statement to update the metadata of Hive tables and Hudi tables cached in StarRocks.

Examples​

Usage examples in different cases are as follows:

External table​

Example 1: Update the cached metadata of the corresponding Hive table in StarRocks by specifying the external table hive1.

REFRESH EXTERNAL TABLE hive1;

Example 2: Update the cached metadata of the partitions of the corresponding Hudi table in StarRocks by specifying the external table hudi1 and the partitions in that table.

REFRESH EXTERNAL TABLE hudi1
PARTITION ('date=2022-12-20', 'date=2022-12-21');

External catalog​

Example 1: Update the metadata of hive_table cached in StarRocks.

REFRESH EXTERNAL TABLE hive_catalog.hive_db.hive_table;

Or

USE hive_catalog.hive_db;
REFRESH EXTERNAL TABLE hive_table;

Example 2: Update the metadata of the second-level partition p2 in hive_table cached in StarRocks.

USE hive_catalog.hive_db;
REFRESH EXTERNAL TABLE hive_table PARTITION ('p1=${date}/p2=${hour}');

Example 3: Update the metadata of the partitions of hudi_table cached in StarRocks.

REFRESH EXTERNAL TABLE hudi_catalog.hudi_db.hudi_table
PARTITION ('date=2022-12-20', 'date=2022-12-21');