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https://issues.apache.org/jira/browse/FLINK-14297?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Timo Walther updated FLINK-14297:
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Component/s: (was: Table SQL / Legacy Planner)
> Temporal Table Function Build Side does not accept a constant key
> -----------------------------------------------------------------
>
> Key: FLINK-14297
> URL: https://issues.apache.org/jira/browse/FLINK-14297
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / Planner
> Affects Versions: 1.9.0
> Environment: Java 1.8, Scala 2.11, Flink 1.9 (pom.xml file attached)
> Reporter: Benoît Paris
> Priority: Minor
> Labels: auto-deprioritized-major
> Attachments: flink-test-temporal-constant-key-build-side.zip
>
>
> When defining a table that will be used as the build side on a Temporal Table
> Function, a constant key will not be accepted:
> In:
> {code:java}
> Table ratesHistory = tEnv.sqlQuery(sql);
> TemporalTableFunction rates =
> ratesHistory.createTemporalTableFunction("r_proctime", "r_currency");
> {code}
> This crashes:
> {code:java}
> SELECT
> 'Eur1' AS r_currency,
> r_amount,
> r_proctime
> FROM RatesHistory{code}
> Making a type verification in Calcite fail:
> RelOptUtil.verifyTypeEquivalence, when trying to join the Lateral Table
> Function. It seems like this is a corner case in nullability, the error is:
> {code:java}
> (Blink)
> Apply rule [LogicalCorrelateToJoinFromTemporalTableFunctionRule] [...]
> (old planner)
> Apply rule [LogicalCorrelateToTemporalTableJoinRule] [...]
> Exception in thread "main" java.lang.AssertionError: Cannot add expression of
> different type to set:
> set type is RecordType(
> [...] VARCHAR(65536) CHARACTER SET "UTF-16LE" r_currency,
> [...]) NOT NULL
> expression type is RecordType(
> [...] CHAR(4) CHARACTER SET "UTF-16LE" NOT NULL r_currency,
> [...]) NOT NULL{code}
> (formatting and commenting mine)
> No problem in VARCHAR vs CHAR, as using the following works:
> {code:java}
> SELECT
> COALESCE('Eur1', r_currency) AS r_currency,
> r_amount,
> r_proctime
> FROM RatesHistory{code}
> The problem is coming from nullable vs NOT NULL
> Attached is Java reproduction code, pom.xml, and both blink and old planner
> logs and stacktraces.
> ----
> My speculations on this is that an earlier transformation infers and
> normalizes the key type (or maybe gets it from the query side?), but the
> decorrelation and special temporal table function case happens later.
> Reordering the rules could help? Maybe way too heavy handed.
> Or do this
> [rexBuilder.makeInputRef|https://github.com/apache/flink/blob/master/flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/planner/plan/rules/logical/LogicalCorrelateToJoinFromTemporalTableFunctionRule.scala#L145]
> in a type-compatible way.
> ----
> This seems to be related to another issue:
> https://issues.apache.org/jira/browse/FLINK-14173
> Where careful support of the the nullability of the build side key in a LEFT
> JOIN will take part in the output.
> ----
> This might seem like a useless use case, but a constant key is the only way
> to access in SQL a Temporal Table Function for a global value (like querying
> a global current number)
>
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