SQL: Fix issue with CAST and NULL checking. #50371
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Previously, during expression optimization, CAST would be considered
nullable if the casted expression resulted to a NULL literal, and would
be always non-nullable otherwise. As a result if CASE was wrapped by a
null check function like `IS NULL` or `IS NOT NULL` it was simplified to
TRUE/FALSE, eliminating the actual casting operation. So in case of an
expression with an erroneous casting like `CAST('foo' AS DATETIME) IS NULL`
it would be simplified to `FALSE` instead of throwing an Exception signifying
the attempt to cast 'foo' to a DATETIME type.
CAST now always returns Nullability.UKNOWN except from the case that
its result evaluated to a constant NULL, so it returns Nullability.TRUE.
Fixes: elastic#50191
|
Pinging @elastic/es-search (:Search/SQL) |
nik9000
approved these changes
Dec 19, 2019
|
I am not sure about the consistency of the behavior here and I'm open for discussing this further. Doing |
|
@astefan added tests to check the thrown exception and added more info in the description to clarify the fix. |
matriv
added a commit
that referenced
this pull request
Dec 20, 2019
Previously, during expression optimisation, CAST would be considered
nullable if the casted expression resulted to a NULL literal, and would
be always non-nullable otherwise. As a result if CASE was wrapped by a
null check function like IS NULL or IS NOT NULL it was simplified to
TRUE/FALSE, eliminating the actual casting operation. So in case of an
expression with an erroneous casting like CAST('foo' AS DATETIME) IS NULL
it would be simplified to FALSE instead of throwing an Exception signifying
the attempt to cast 'foo' to a DATETIME type.
CAST now always returns Nullability.UKNOWN except from the case that
its result evaluated to a constant NULL, where it returns Nullability.TRUE.
This way the IS NULL/IS NOT NULL don't get simplified to FALSE/TRUE
and the CAST actually gets evaluated resulting to a thrown Exception.
Fixes: #50191
(cherry picked from commit 671e07a)
matriv
added a commit
that referenced
this pull request
Dec 20, 2019
Previously, during expression optimisation, CAST would be considered
nullable if the casted expression resulted to a NULL literal, and would
be always non-nullable otherwise. As a result if CASE was wrapped by a
null check function like IS NULL or IS NOT NULL it was simplified to
TRUE/FALSE, eliminating the actual casting operation. So in case of an
expression with an erroneous casting like CAST('foo' AS DATETIME) IS NULL
it would be simplified to FALSE instead of throwing an Exception signifying
the attempt to cast 'foo' to a DATETIME type.
CAST now always returns Nullability.UKNOWN except from the case that
its result evaluated to a constant NULL, where it returns Nullability.TRUE.
This way the IS NULL/IS NOT NULL don't get simplified to FALSE/TRUE
and the CAST actually gets evaluated resulting to a thrown Exception.
Fixes: #50191
(cherry picked from commit 671e07a)
matriv
added a commit
that referenced
this pull request
Dec 20, 2019
Previously, during expression optimisation, CAST would be considered
nullable if the casted expression resulted to a NULL literal, and would
be always non-nullable otherwise. As a result if CASE was wrapped by a
null check function like IS NULL or IS NOT NULL it was simplified to
TRUE/FALSE, eliminating the actual casting operation. So in case of an
expression with an erroneous casting like CAST('foo' AS DATETIME) IS NULL
it would be simplified to FALSE instead of throwing an Exception signifying
the attempt to cast 'foo' to a DATETIME type.
CAST now always returns Nullability.UKNOWN except from the case that
its result evaluated to a constant NULL, where it returns Nullability.TRUE.
This way the IS NULL/IS NOT NULL don't get simplified to FALSE/TRUE
and the CAST actually gets evaluated resulting to a thrown Exception.
Fixes: #50191
(cherry picked from commit 671e07a)
SivagurunathanV
pushed a commit
to SivagurunathanV/elasticsearch
that referenced
this pull request
Jan 23, 2020
Previously, during expression optimisation, CAST would be considered
nullable if the casted expression resulted to a NULL literal, and would
be always non-nullable otherwise. As a result if CASE was wrapped by a
null check function like IS NULL or IS NOT NULL it was simplified to
TRUE/FALSE, eliminating the actual casting operation. So in case of an
expression with an erroneous casting like CAST('foo' AS DATETIME) IS NULL
it would be simplified to FALSE instead of throwing an Exception signifying
the attempt to cast 'foo' to a DATETIME type.
CAST now always returns Nullability.UKNOWN except from the case that
its result evaluated to a constant NULL, where it returns Nullability.TRUE.
This way the IS NULL/IS NOT NULL don't get simplified to FALSE/TRUE
and the CAST actually gets evaluated resulting to a thrown Exception.
Fixes: elastic#50191
This was referenced Feb 3, 2020
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Previously, during expression optimisation, CAST would be considered
nullable if the casted expression resulted to a NULL literal, and would
be always non-nullable otherwise. As a result if CASE was wrapped by a
null check function like
IS NULLorIS NOT NULLit was simplified toTRUE/FALSE, eliminating the actual casting operation. So in case of an
expression with an erroneous casting like
CAST('foo' AS DATETIME) IS NULLit would be simplified to
FALSEinstead of throwing an Exception signifyingthe attempt to cast 'foo' to a DATETIME type.
CAST now always returns Nullability.UKNOWN except from the case that
its result evaluated to a constant NULL, where it returns Nullability.TRUE.
This way the IS NULL/IS NOT NULL don't get simplified to FALSE/TRUE
and the CAST actually gets evaluated resulting to a thrown Exception.
Fixes: #50191