REFRESH EXTERNAL TABLE

Description

Updates Hive and Hudi metadata cached in CelerData. This statement is used in one of 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 CelerData.
• External catalog: When using a Hive catalog or Hudi catalog to query data in Hive or Hudi, you can execute this statement to update the metadata of a Hive table or Hudi table cached in CelerData.

Basic concepts

• Hive external table: is created and stored in CelerData. You can use it to query Hive data.
• Hudi external table: is created and stored in CelerData. 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', ...)]

  Parameter	Required	Description
  table_name	Yes	The name of a Hive external table or Hudi external table.
  partition_name	No	The 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 CelerData.

• External catalog

  REFRESH EXTERNAL TABLE [external_catalog.][db_name.]table_name
  [PARTITION ('partition_name', ...)]

  Parameter	Required	Description
  external_catalog	No	The name of a Hive catalog or Hudi catalog.
  db_name	No	The name of the database where a Hive table or Hudi table resides.
  table_name	Yes	The name of a Hive table or a Hudi table.
  partition_name	No	The 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 CelerData.

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 CelerData.

Examples

Usage examples in different cases are as follows:

External table

Example 1: Update the cached metadata of the corresponding Hive table in CelerData 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 CelerData by specifying the external table hudi1 and the partitions of the corresponding Hudi table.

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

External catalog

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

REFRESH EXTERNAL TABLE hive_catalog.hive_db.hive_table;

Or

USE hive_catalog.hive_db;
REFRESH EXTERNAL TABLE hive_table;

Example 2: Update the cached metadata of the partitions of hudi_table in CelerData.

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