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https://issues.apache.org/jira/browse/FLINK-24050?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ingo Bürk updated FLINK-24050:
------------------------------
Description:
Currently, primary keys are required to consist solely of physical columns.
However, there might be scenarios where the actual payload/records do not
contain a suitable primary key, but a unique identifier is available through
metadata. In this case it would make sense to define the primary key on such a
metadata column:
{code:java}
CREATE TABLE T (
uid STRING METADATA,
content STRING
PRIMARY KEY (uid) NOT ENFORCED
) WITH (…)
{code}
A simple example for this would be IMAP: there is nothing unique about any
single email as a record, but each email in a specific folder on an IMAP server
has a unique UID (I'm excluding some irrelevant technical details here).
See FLINK-24512 for another (probably better) use case.
was:
Currently, primary keys are required to consist solely of physical columns.
However, there might be scenarios where the actual payload/records do not
contain a suitable primary key, but a unique identifier is available through
metadata. In this case it would make sense to define the primary key on such a
metadata column:
{code:java}
CREATE TABLE T (
uid STRING METADATA,
content STRING
PRIMARY KEY (uid) NOT ENFORCED
) WITH (…)
{code}
A simple example for this would be IMAP: there is nothing unique about any
single email as a record, but each email in a specific folder on an IMAP server
has a unique UID (I'm excluding some irrelevant technical details here).
> Support primary keys on metadata columns
> ----------------------------------------
>
> Key: FLINK-24050
> URL: https://issues.apache.org/jira/browse/FLINK-24050
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / API
> Reporter: Ingo Bürk
> Priority: Major
>
> Currently, primary keys are required to consist solely of physical columns.
> However, there might be scenarios where the actual payload/records do not
> contain a suitable primary key, but a unique identifier is available through
> metadata. In this case it would make sense to define the primary key on such
> a metadata column:
> {code:java}
> CREATE TABLE T (
> uid STRING METADATA,
> content STRING
> PRIMARY KEY (uid) NOT ENFORCED
> ) WITH (…)
> {code}
> A simple example for this would be IMAP: there is nothing unique about any
> single email as a record, but each email in a specific folder on an IMAP
> server has a unique UID (I'm excluding some irrelevant technical details
> here).
> See FLINK-24512 for another (probably better) use case.
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