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[GitHub] [spark] gengliangwang opened a new pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
gengliangwang opened a new pull request #35478:
URL: https://github.com/apache/spark/pull/35478
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Compared to the default behavior, the current ANSI type coercion rules don't allow the following cases:
- comparing String with other simple types, e.g. date/timestamp/int ...
- arithmetic operation containing String and other simple types
- Union/Intersect/Except containing String and other simple types
- SQL function expects non-string types but got string input
- other SQL operators..
This PR is to remove the limitation. After changes, the String type can be implicit cast as Long/Double/Date/Timestamp/Boolean/Binary/Interval.
Note that Byte/Short/Int is not on the precedent list of String: `str_col > 1` will become `cast(str_col as long) > 1L`. So that we can avoid string parsing error if the string is out of the range of Byte/Short/Int in comparison/arithmetic/union operations.
The design applies to Float/Decimal (especially Decimal), for SQL operators containing Float/Decimal and String, the type coercion system will convert both as Double.
### Why are the changes needed?
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The purpose of the current limitation is to prevent potential String parsing errors under ANSI mode. However, after doing research among real-world Spark SQL queries, I find that many users are actually using String as Date/Timestamp/Numeric in their queries. For example, the purpose of query `where date_col > '2022-01-01'` is quite obvious, but users have to rewrite it as `where date_col > date'2022-01-01'` under ANSI mode.
To make the migration to ANSI mode easier, I suggest removing this limitation. Let's treat it as an extension in our SQL dialect.
### Does this PR introduce _any_ user-facing change?
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Yes, allow implicitly casting String to other simple types under ANSI mode
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Unit tests
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[GitHub] [spark] gengliangwang closed pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
Posted by GitBox <gi...@apache.org>.
gengliangwang closed pull request #35478:
URL: https://github.com/apache/spark/pull/35478
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[GitHub] [spark] cloud-fan commented on a change in pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
Posted by GitBox <gi...@apache.org>.
cloud-fan commented on a change in pull request #35478:
URL: https://github.com/apache/spark/pull/35478#discussion_r803710809
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/AnsiTypeCoercion.scala
##########
@@ -171,17 +183,23 @@ object AnsiTypeCoercion extends TypeCoercionBase {
// This type coercion system will allow implicit converting String type literals as other
// primitive types, in case of breaking too many existing Spark SQL queries.
- case (StringType, a: AtomicType) if isInputFoldable =>
+ case (StringType, a: AtomicType) =>
Some(a)
// If the target type is any Numeric type, convert the String type literal as Double type.
- case (StringType, NumericType) if isInputFoldable =>
+ case (StringType, NumericType) =>
Some(DoubleType)
- // If the target type is any Decimal type, convert the String type literal as Double type.
- case (StringType, DecimalType) if isInputFoldable =>
+ // If the target type is any Decimal type, convert the String type literal as the default
Review comment:
please update other similar comments in this file.
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[GitHub] [spark] gengliangwang commented on pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
Posted by GitBox <gi...@apache.org>.
gengliangwang commented on pull request #35478:
URL: https://github.com/apache/spark/pull/35478#issuecomment-1034910692
cc @cloud-fan @entong @allisonwang-db
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[GitHub] [spark] cloud-fan commented on a change in pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
Posted by GitBox <gi...@apache.org>.
cloud-fan commented on a change in pull request #35478:
URL: https://github.com/apache/spark/pull/35478#discussion_r803711080
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/AnsiTypeCoercion.scala
##########
@@ -171,17 +183,23 @@ object AnsiTypeCoercion extends TypeCoercionBase {
// This type coercion system will allow implicit converting String type literals as other
// primitive types, in case of breaking too many existing Spark SQL queries.
- case (StringType, a: AtomicType) if isInputFoldable =>
+ case (StringType, a: AtomicType) =>
Some(a)
// If the target type is any Numeric type, convert the String type literal as Double type.
- case (StringType, NumericType) if isInputFoldable =>
+ case (StringType, NumericType) =>
Some(DoubleType)
- // If the target type is any Decimal type, convert the String type literal as Double type.
- case (StringType, DecimalType) if isInputFoldable =>
+ // If the target type is any Decimal type, convert the String type literal as the default
+ // Decimal type.
+ case (StringType, DecimalType) =>
Some(DecimalType.SYSTEM_DEFAULT)
+ // If the target type is any Decimal type, convert the String type literal as the default
Review comment:
```suggestion
// If the target type is any timestamp type, convert the String type literal as the default
```
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[GitHub] [spark] cloud-fan commented on a change in pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
Posted by GitBox <gi...@apache.org>.
cloud-fan commented on a change in pull request #35478:
URL: https://github.com/apache/spark/pull/35478#discussion_r803710602
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/AnsiTypeCoercion.scala
##########
@@ -171,17 +183,23 @@ object AnsiTypeCoercion extends TypeCoercionBase {
// This type coercion system will allow implicit converting String type literals as other
// primitive types, in case of breaking too many existing Spark SQL queries.
- case (StringType, a: AtomicType) if isInputFoldable =>
+ case (StringType, a: AtomicType) =>
Some(a)
// If the target type is any Numeric type, convert the String type literal as Double type.
- case (StringType, NumericType) if isInputFoldable =>
+ case (StringType, NumericType) =>
Some(DoubleType)
- // If the target type is any Decimal type, convert the String type literal as Double type.
- case (StringType, DecimalType) if isInputFoldable =>
+ // If the target type is any Decimal type, convert the String type literal as the default
Review comment:
nit: not literal anymore
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[GitHub] [spark] cloud-fan commented on a change in pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
Posted by GitBox <gi...@apache.org>.
cloud-fan commented on a change in pull request #35478:
URL: https://github.com/apache/spark/pull/35478#discussion_r803704536
##########
File path: docs/sql-ref-ansi-compliance.md
##########
@@ -188,34 +188,33 @@ java.lang.ArithmeticException: Casting 2147483648 to int causes overflow
When `spark.sql.ansi.enabled` is set to `true`, Spark SQL uses several rules that govern how conflicts between data types are resolved.
At the heart of this conflict resolution is the Type Precedence List which defines whether values of a given data type can be promoted to another data type implicitly.
-| Data type | precedence list(from narrowest to widest) |
-|-----------|------------------------------------------------------------------|
-| Byte | Byte -> Short -> Int -> Long -> Decimal -> Float* -> Double |
-| Short | Short -> Int -> Long -> Decimal-> Float* -> Double |
-| Int | Int -> Long -> Decimal -> Float* -> Double |
-| Long | Long -> Decimal -> Float* -> Double |
-| Decimal | Decimal -> Float* -> Double |
-| Float | Float -> Double |
-| Double | Double |
-| Date | Date -> Timestamp |
-| Timestamp | Timestamp |
-| String | String |
-| Binary | Binary |
-| Boolean | Boolean |
-| Interval | Interval |
-| Map | Map** |
-| Array | Array** |
-| Struct | Struct** |
+| Data type | precedence list(from narrowest to widest) |
+|-----------|----------------------------------------------------------------------|
+| Byte | Byte -> Short -> Int -> Long -> Decimal -> Float* -> Double |
+| Short | Short -> Int -> Long -> Decimal-> Float* -> Double |
+| Int | Int -> Long -> Decimal -> Float* -> Double |
+| Long | Long -> Decimal -> Float* -> Double |
+| Decimal | Decimal -> Float* -> Double |
+| Float | Float -> Double |
+| Double | Double |
+| Date | Date -> Timestamp |
+| Timestamp | Timestamp |
+| String | String, Long -> Double, Date -> Timestamp, Boolean, Interval, Binary |
Review comment:
I find this line a bit hard to understand. Shall we add some explanation below?
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[GitHub] [spark] gengliangwang commented on pull request #35478: [SPARK-38176][SQL] ANSI mode: allow implicitly casting String to other simple types
Posted by GitBox <gi...@apache.org>.
gengliangwang commented on pull request #35478:
URL: https://github.com/apache/spark/pull/35478#issuecomment-1035862125
Merging to master for unblocking https://issues.apache.org/jira/browse/SPARK-38154
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