[FLINK-13461] Distinguish between temporary tables and persisted tables

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Fix Version/s: 1.10.0
• Component/s: Table SQL / API
• Assignee: Dawid Wysakowicz
• Reporter: Dawid Wysakowicz
• Created: 29/Jul/19 08:18
• Updated: 08/Nov/19 12:52
• Resolved: 08/Nov/19 12:52

Description

Currently, there is no difference between temporary tables that are only available to the current session and tables that need to be persisted in a catalog. FLINK-13279 is an example for this shortcoming. Because we introduce the first real catalog support in Flink 1.9, the difference becomes more important to users.

A user must be able to express whether a table is just temporary or get an exception if it can not be persisted as desired. Currently, non-persisted tables are silently stored in a separate volatile data structure.

This issue might touch API, DDL, and SQL Client. We should discuss how we approach this issue for the 1.9 release.

Some background information for people that would like to join the discussion:

MySQL:
https://dev.mysql.com/doc/refman/8.0/en/create-temporary-table.html
http://www.mysqltutorial.org/mysql-temporary-table/

Spark:
https://spark.apache.org/docs/latest/sql-getting-started.html#global-temporary-view

SQL Server:
https://docs.microsoft.com/en-us/sql/t-sql/statements/create-table-transact-sql?view=sql-server-2017
https://docs.microsoft.com/de-de/sql/relational-databases/databases/tempdb-database?view=sql-server-2017

Issue Links

• is a clone of: FLINK-13350 Mark useCatalog & useDatabase as Experimental for 1.9 release
• is duplicated by: FLINK-14485 Support for Temporary Objects in Table module
• relates to: FLINK-13279 not able to query table registered in catalogs in SQL CLI

Sub-Tasks

• Mark useCatalog & useDatabase as Experimental for 1.9 release: Closed