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https://issues.apache.org/jira/browse/CALCITE-7264?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thomas Rebele updated CALCITE-7264:
-----------------------------------
Description:
The SQL standard defines that 1/0 throws an exception. Calcite follows the
standard here. However, some projects that use Calcite (e.g., Hive) define the
result of 1/0 as NULL. This may lead to different results in RexSimplify: E.g.,
IS NULL(1/0) would throw for the SQL standard semantics, but would return TRUE
for the Hive semantics.
RexSimplify handles this with a concept called "safe" defined in
[RexSimplify#isSafeExpression|https://github.com/apache/calcite/blob/34989b0ed7793cedf713c2f159de6247a730458c/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1631].
The safe operators are defined in
[RexSimplify.SafeRexVisitor|https://github.com/apache/calcite/blob/34989b0ed7793cedf713c2f159de6247a730458c/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1490].
The goal of this ticket is to make the behavior configurable. The API would
need to provide a method that accepts at least RexCall nodes. Maybe a more
general approach is favorable, e.g., {{{}isSafeExpression(RexNode r){}}}.
This ticket aims to provide a refinement of
{{{}org.apache.calcite.sql.SqlOperator#isSafeOperator{}}}, which only takes the
operator but not the arguments into account. To be discussed whether the new
API replaces or supplements {{{}SqlOperator#isSafeOperator{}}}.
The safeness information would be useful for other parts of the code as well,
e.g., CALCITE-5315.
See the related discussions:
*
https://issues.apache.org/jira/browse/CALCITE-7145?focusedCommentId=18016030#comment-18016030
* [http://lists.apache.org/thread/cp7h28k1yfxv421q12y1wopbwgrzdzrx]
was:
The SQL standard defines that 1/0 throws an exception. Calcite follows the
standard here. However, some projects that use Calcite (e.g., Hive) define the
result of 1/0 as NULL. This may lead to different results in RexSimplify: E.g.,
IS NULL(1/0) would throw for the SQL standard semantics, but would return TRUE
for the Hive semantics.
RexSimplify handles this with a concept called "safe" defined in
[RexSimplify#isSafeExpression|https://github.com/apache/calcite/blob/34989b0ed7793cedf713c2f159de6247a730458c/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1631].
The safe operators are defined in
[RexSimplify.SafeRexVisitor|https://github.com/apache/calcite/blob/34989b0ed7793cedf713c2f159de6247a730458c/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1490].
The goal of this ticket is to make the behavior configurable. We can continue
to attach the safeness to the operators, so we could move the safeOps set
somewhere else. Here some examples:
* boolean RelDataTypeSystem#canOperatorThrow(SqlKind op)
* boolean RelDataTypeSystem#canOperatorThrow(SqlOperator op)
* boolean RelDataTypeSystem#isNoExceptOperator(...) //noexcept notion borrowed
from C++
* boolean RelDataTypeSystem#isSafeOperator
* Set<SqlKind> RelDataTypeSystem#noexceptOperators()
The safeness information would be useful for other parts of the code as well,
e.g., CALCITE-5315.
See the related discussions:
*
https://issues.apache.org/jira/browse/CALCITE-7145?focusedCommentId=18016030#comment-18016030
* [http://lists.apache.org/thread/cp7h28k1yfxv421q12y1wopbwgrzdzrx]
> New API for determining if an operator may throw
> ------------------------------------------------
>
> Key: CALCITE-7264
> URL: https://issues.apache.org/jira/browse/CALCITE-7264
> Project: Calcite
> Issue Type: New Feature
> Reporter: Thomas Rebele
> Priority: Major
>
> The SQL standard defines that 1/0 throws an exception. Calcite follows the
> standard here. However, some projects that use Calcite (e.g., Hive) define
> the result of 1/0 as NULL. This may lead to different results in RexSimplify:
> E.g., IS NULL(1/0) would throw for the SQL standard semantics, but would
> return TRUE for the Hive semantics.
> RexSimplify handles this with a concept called "safe" defined in
> [RexSimplify#isSafeExpression|https://github.com/apache/calcite/blob/34989b0ed7793cedf713c2f159de6247a730458c/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1631].
> The safe operators are defined in
> [RexSimplify.SafeRexVisitor|https://github.com/apache/calcite/blob/34989b0ed7793cedf713c2f159de6247a730458c/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1490].
> The goal of this ticket is to make the behavior configurable. The API would
> need to provide a method that accepts at least RexCall nodes. Maybe a more
> general approach is favorable, e.g., {{{}isSafeExpression(RexNode r){}}}.
> This ticket aims to provide a refinement of
> {{{}org.apache.calcite.sql.SqlOperator#isSafeOperator{}}}, which only takes
> the operator but not the arguments into account. To be discussed whether the
> new API replaces or supplements {{{}SqlOperator#isSafeOperator{}}}.
> The safeness information would be useful for other parts of the code as well,
> e.g., CALCITE-5315.
> See the related discussions:
> *
> https://issues.apache.org/jira/browse/CALCITE-7145?focusedCommentId=18016030#comment-18016030
> * [http://lists.apache.org/thread/cp7h28k1yfxv421q12y1wopbwgrzdzrx]
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