THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Status
Current state: Under DiscussionAccepted
Discussion thread: https://lists.apache.org/thread/m4r3wrd7p96wdst3nz3ncqzog6kf51cf
JIRA:
here (<- link to Vote thread: https://issueslists.apache.org/thread/jira/browse/FLINK-XXXX)fosvz0zcyfn6bp6vz2oxl45vq9qhkn2v
JIRA:
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Released: <Flink Version>1.18.0
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
The TRUNCATE TABLE statement is a SQL command that allows users to quickly and efficiently delete all rows from a table without dropping the table itself. This statement is commonly used in data warehouse, where large data sets are frequently loaded and unloaded from tables. It can improve performance by reducing the amount of time and resources required to delete large amounts of data.
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Considering the TRUNCATE TABLE statment is useful and widely-used, this FLIP is aimed to support TRUNCATE TABLE statment in Flink. This FLIP will bring Flink the TRUNCATE TABLE syntax and an interface with which the coresponding connectors can implement their own logic for truncating table.
Note: Considering the use cases of truncate table are mainly for batch scenario and the semantic in stream scenario should be discussed separately, this FLIP to to support truncate table in batch only.
Public Interfaces
Syntax
We propose add the following syntax for TRUNCATE TABLE statement.
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TRUNCATE TABLE table_name |
It supports trucate permanent or temporary table, if it's a view table, it should throw TableException with message Truncate a view table is not support .
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Public interfaces Changes
We propose add a inerface for TRUNCATE TABLE statment. The connectors can implement this interface to custom their logic for truncating table.
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/**
* Enables to delete all existing data in a {@link DynamicTableSink} table using {@code TRUNCATE
* TABLE} statement.
*
* <p>For {@code TRUNCATE TABLE} statement, if the corresponding {@link DynamicTableSink} have
* implemented this interface, then the method {@link #truncateTable()} will be invoked in execution
* phase. Otherwise, Flink will throw an exception directly.
*/
@PublicEvolving
public interface SupportsTruncate {
/**
* Execute truncating table.
*
* @return trueNote: please remember to throw exception if truncate the table successfully otherwise falsethe truncation hasn't been executed successfully,
* otherwise it'll be still considered to haven been executed successfully by Flink.
*/
booleanvoid executeTruncation();
} |
Proposed Changes
1: Add a parse rule in parserImpls.ftl to match TRUNCATE TABLE statement and convert it to SqlTruncateTable
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3: TruncateTableOperation should implement ExecutableOperation, and in method get the #execute(Context ctx), it will DynamicTableSink of the table which should implement SupportsTruncate and then call method SupportsTruncate#executeTruncation directly to truncate the table. If the DynamicTableSink doesn't implemente this interface, it should throw TableException('The truncate statement for the table is not supported as it hasn't implemented the interface SupportsTruncate') . For some sinks that doesn't support deleting data, it can also implements this interface but throw more concrete exception like "xxx donesn't support to truncate a table as delete is impossible for xxx".
Compatibility, Deprecation, and Migration Plan
No any compatibility issue.
Test Plan
It'll be covered by UT & IT.
Rejected Alternatives
If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.