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[FLINK-12254][table] Update cast() and TypeLiteralExpression to new type system #8510

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twalthr wants to merge 2 commits into from
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[FLINK-12254][table] Update cast() and TypeLiteralExpression to new type system #8510

twalthr wants to merge 2 commits into from

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@twalthr twalthr commented May 22, 2019

What is the purpose of the change

This PR updates ImplicitExpressionOperations#cast and TypeLiteralExpression. The Java expression API remains untouched for now.

This PR builds on top of #8500.

Brief change log

  • Deprecate old cast()
  • Update TypeLiteralExpression
  • Use legacy conversion where applicable

Verifying this change

This change is already covered by existing tests.

Does this pull request potentially affect one of the following parts:

  • Dependencies (does it add or upgrade a dependency): no
  • The public API, i.e., is any changed class annotated with @Public(Evolving): yes
  • The serializers: no
  • The runtime per-record code paths (performance sensitive): no
  • Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: no
  • The S3 file system connector: no

Documentation

  • Does this pull request introduce a new feature? no
  • If yes, how is the feature documented? JavaDocs

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flinkbot commented May 22, 2019 •
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@twalthr twalthr force-pushed the FLINK-12254_CAST branch from dbce146 to 00a2f44 Compare May 23, 2019 08:11
dawidwys
dawidwys approved these changes May 27, 2019
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Generally +1. Before merging I would only slightly improve the deprecation note on expressionDsl#cast

...ink-table-common/src/main/java/org/apache/flink/table/expressions/TypeLiteralExpression.java

/**
* Expression that wraps {@link TypeInformation} as a literal.
* Expression that wraps {@link DataType} as a literal.
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nit: How about we add a note why do we need it? That this is primarily used for casts.

...able/flink-table-planner/src/main/scala/org/apache/flink/table/api/scala/expressionDsl.scala Outdated
call(CAST, expr, typeLiteral(toType))

/**
* @deprecated Use [[cast(DataType)]] instead.
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nit: Could we add a bit longer note that it might be unsafe to mix the DataType and TypeInformation stacks?

...link-table-api-java/src/main/java/org/apache/flink/table/expressions/ApiExpressionUtils.java
// check for constant
return ExpressionUtils.extractValue(e, BasicTypeInfo.INT_TYPE_INFO)
.map((v) -> (Expression) valueLiteral(v * multiplier, TimeIntervalTypeInfo.INTERVAL_MONTHS))
.orElse(
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This changes the behavior of this method right? Previously e.g. (1 + 3).toMonthInterval or even (1 + f0).toMonthInterval was possible right? (Even though e.g. the window aggregation did not accept it)

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@twalthr twalthr May 27, 2019

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Yes, that's right but this behavior was not even tested somewhere and for simplification of the design I think it is ok to limit the values to constants. What do you think?

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I agree, just wanted to double check.

@twalthr twalthr force-pushed the FLINK-12254_CAST branch from 00a2f44 to 9490e4b Compare May 27, 2019 09:21
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twalthr commented May 27, 2019

Thanks for the feedback @dawidwys. I updated the PR. Will merge this once Travis is green.

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dawidwys commented May 27, 2019

@flinkbot approve all

@asfgit asfgit closed this in b336b6d May 27, 2019
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