[FLINK-20307] Improve the documentation about the temporal table join syntax

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Invalid
• Fix Version/s: 1.12.0
• Component/s: Documentation, Table SQL / Planner
• Labels: pull-request-available
• Assignee: Danny Chen
• Reporter: Dawid Wysakowicz
• Created: 23/Nov/20 18:47
• Updated: 24/Nov/20 10:52
• Resolved: 24/Nov/20 10:52

Description

A query like:

SELECT p.name, p.qty * r.rate AS price, p.`tstamp` FROM Products p JOIN versioned_rates r FOR SYSTEM_TIME AS OF p.`tstamp` ON p.currency = r.currency;

fails with:

[ERROR] Could not execute SQL statement. Reason:
org.apache.flink.sql.parser.impl.ParseException: Encountered "FOR" at line 1, column 108.
Was expecting one of:
    <EOF> 
    "EXCEPT" ...
    "FETCH" ...
    "GROUP" ...
    "HAVING" ...
    "INTERSECT" ...
    "LIMIT" ...
    "OFFSET" ...
    "ON" ...
    "ORDER" ...
    "MINUS" ...
    "TABLESAMPLE" ...
    "UNION" ...
    "USING" ...
    "WHERE" ...
    "WINDOW" ...
    "(" ...
    "NATURAL" ...
    "JOIN" ...
    "INNER" ...
    "LEFT" ...
    "RIGHT" ...
    "FULL" ...
    "CROSS" ...
    "," ...
    "OUTER" ...

When I do not alias the versioned_rates table everything works as expected. Therefore query like just runs:

SELECT p.name, p.qty * versioned_rates.rate AS price, p.`tstamp` FROM Products p JOIN versioned_rates FOR SYSTEM_TIME AS OF p.`tstamp` ON p.currency = versioned_rates.currency;

Issue Links

• relates to: FLINK-20119 Test Temporal Table DDL and Temporal Table Join
• links to: GitHub Pull Request #14193