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Posted to reviews@spark.apache.org by GitBox <gi...@apache.org> on 2021/03/29 05:25:55 UTC
[GitHub] [spark] maropu commented on a change in pull request #31982: [SPARK-34881][SQL] New SQL Function: TRY_CAST
maropu commented on a change in pull request #31982:
URL: https://github.com/apache/spark/pull/31982#discussion_r603013688
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/TryCast.scala
##########
@@ -0,0 +1,88 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.catalyst.expressions
+
+import org.apache.spark.sql.catalyst.expressions.codegen._
+import org.apache.spark.sql.catalyst.expressions.codegen.Block._
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.types.DataType
+
+/**
+ * A special version of [[AnsiCast]]. It performs the same operation (i.e. converts a value of
+ * one data type into another data type), but returns a NULL value instead of raising an error
+ * when the conversion can not be performed.
+ *
+ * When cast from/to timezone related types, we need timeZoneId, which will be resolved with
+ * session local timezone by an analyzer [[ResolveTimeZone]].
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(expr AS type) - Casts the value `expr` to the target data type `type`. " +
+ "This expression is identical to CAST with `spark.sql.ansi.enabled` as true, " +
+ "except it returns NULL instead of raising an error. " +
+ "This expression has one major difference from `cast` with `spark.sql.ansi.enabled` as true: " +
+ "when the source value can't be stored in the target integral(Byte/Short/Int/Long) type, " +
+ "`try_cast` returns null instead of returning the low order bytes of the source value.",
Review comment:
nit: `try_cast` => `_FUNC_`?
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/TryCast.scala
##########
@@ -0,0 +1,88 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.catalyst.expressions
+
+import org.apache.spark.sql.catalyst.expressions.codegen._
+import org.apache.spark.sql.catalyst.expressions.codegen.Block._
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.types.DataType
+
+/**
+ * A special version of [[AnsiCast]]. It performs the same operation (i.e. converts a value of
+ * one data type into another data type), but returns a NULL value instead of raising an error
+ * when the conversion can not be performed.
+ *
+ * When cast from/to timezone related types, we need timeZoneId, which will be resolved with
+ * session local timezone by an analyzer [[ResolveTimeZone]].
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(expr AS type) - Casts the value `expr` to the target data type `type`. " +
+ "This expression is identical to CAST with `spark.sql.ansi.enabled` as true, " +
+ "except it returns NULL instead of raising an error. " +
+ "This expression has one major difference from `cast` with `spark.sql.ansi.enabled` as true: " +
Review comment:
ditto
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
##########
@@ -1610,6 +1610,17 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef] with SQLConfHelper with Logg
cast
}
+ /**
+ * Create a [[TryCast]] expression.
+ */
+ override def visitTryCast(ctx: TryCastContext): Expression = withOrigin(ctx) {
Review comment:
`visitCast` and `visitTryCast` are similar between each other, so how about merging their definition in `SqlBase.sql`?
```
| cast=(CAST | TRY_CAST) '(' expression AS dataType ')' #cast
```
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/TryCast.scala
##########
@@ -0,0 +1,88 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.catalyst.expressions
+
+import org.apache.spark.sql.catalyst.expressions.codegen._
+import org.apache.spark.sql.catalyst.expressions.codegen.Block._
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.types.DataType
+
+/**
+ * A special version of [[AnsiCast]]. It performs the same operation (i.e. converts a value of
+ * one data type into another data type), but returns a NULL value instead of raising an error
+ * when the conversion can not be performed.
+ *
+ * When cast from/to timezone related types, we need timeZoneId, which will be resolved with
+ * session local timezone by an analyzer [[ResolveTimeZone]].
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(expr AS type) - Casts the value `expr` to the target data type `type`. " +
+ "This expression is identical to CAST with `spark.sql.ansi.enabled` as true, " +
Review comment:
nti: `spark.sql.ansi.enabled` -> `SQLConf.ANSI_ENABLED.key`?
##########
File path: sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
##########
@@ -4118,6 +4118,26 @@ class SQLQuerySuite extends QueryTest with SharedSparkSession with AdaptiveSpark
}
}
+ test("try_cast") {
Review comment:
Could we move this test into `SQLQueryTestSuite`?
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/TryCast.scala
##########
@@ -0,0 +1,88 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.catalyst.expressions
+
+import org.apache.spark.sql.catalyst.expressions.codegen._
+import org.apache.spark.sql.catalyst.expressions.codegen.Block._
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.types.DataType
+
+/**
+ * A special version of [[AnsiCast]]. It performs the same operation (i.e. converts a value of
+ * one data type into another data type), but returns a NULL value instead of raising an error
+ * when the conversion can not be performed.
+ *
+ * When cast from/to timezone related types, we need timeZoneId, which will be resolved with
+ * session local timezone by an analyzer [[ResolveTimeZone]].
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(expr AS type) - Casts the value `expr` to the target data type `type`. " +
+ "This expression is identical to CAST with `spark.sql.ansi.enabled` as true, " +
Review comment:
In the first statement, how about explicitly saying that this behaviour follow the ANSI rule?
##########
File path: sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
##########
@@ -4118,6 +4118,26 @@ class SQLQuerySuite extends QueryTest with SharedSparkSession with AdaptiveSpark
}
}
+ test("try_cast") {
+ Seq("true", "false").foreach { ansiEnabled =>
+ withSQLConf(SQLConf.ANSI_ENABLED.key -> ansiEnabled) {
Review comment:
It looks this expr itself does not depend on the ansi option, but we need tests for ansi=true?
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