Help Center/ Data Lake Insight/ SQL Syntax Reference (Paris Region)/ Spark SQL Syntax Reference/ Backing Up and Restoring Data of Multiple Versions/ Configuring the Trash Bin for Expired Multiversion Data
Updated on 2022-12-07 GMT+08:00
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Configuring the Trash Bin for Expired Multiversion Data

Function

After the multiversion function is enabled, expired backup data will be directly deleted by the system when the insert overwrite or truncate statement is executed. You can configure the trash bin of the OBS parallel file system to accelerate the deletion of expired backup data. To enable the trash bin, add dli.multi.version.trash.dir to the table properties. For details about the syntax for enabling or disabling the multiversion function, see Enabling or Disabling Multiversion Backup.

Currently, the multiversion function supports only OBS tables created using the Hive syntax. For details about the syntax for creating a table, see Creating an OBS Table Using the Hive Syntax.

Syntax

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ALTER TABLE [db_name.]table_name 
SET TBLPROPERTIES ("dli.multi.version.trash.dir"="OBS bucket for expired multiversion backup data");

Keyword

  • TBLPROPERTIES: This keyword is used to add a key/value property to a table.

Parameter

Table 1 Parameter description

Parameter

Description

db_name

Database name, which consists of letters, digits, and underscores (_). The value cannot contain only digits or start with a digit or underscore (_).

table_name

Table name

OBS bucket for expired multiversion backup data

A directory in the bucket where the current OBS table locates. You can change the directory path as needed. For example, if the current OBS table directory is obs://bucketName/filePath and a Trash directory has been created in the OBS table directory, you can set the trash bin directory to obs://bucketName/filePath/Trash.

Precautions

  • Currently, the multiversion function supports only OBS tables created using the Hive syntax. For details about the syntax for creating a table, see Creating an OBS Table Using the Hive Syntax.
  • To automatically empty the trash bin, you need to configure a lifecycle rule for the bucket of the OBS parallel file system. The procedure is as follows:
    1. On the OBS console, choose Parallel File System in the left navigation pane. Click the name of the target file system. The Overview page is displayed.
    2. In the left navigation pane, choose Basic Configurations > Lifecycle Rules to create a lifecycle rule.

Example

Configure the trash bin to accelerate the deletion of expired backup data. The data is dumped to the /.Trash directory in OBS. 
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ALTER TABLE test_table 
SET TBLPROPERTIES ("dli.multi.version.trash.dir"="/.Trash");