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https://issues.apache.org/jira/browse/DRILL-6768?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16645074#comment-16645074
]
ASF GitHub Bot commented on DRILL-6768:
---------------------------------------
KazydubB commented on a change in pull request #1494: DRILL-6768: Improve
to_date, to_time and to_timestamp and correspondi…
URL: https://github.com/apache/drill/pull/1494#discussion_r223664902
##########
File path:
exec/java-exec/src/main/codegen/templates/DateIntervalFunctionTemplates/EmptyStringToDateTypeFunctions.java
##########
@@ -0,0 +1,78 @@
+/*
+ * 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.
+ */
+import org.apache.drill.exec.expr.annotations.Workspace;
+
+<@pp.dropOutputFile />
+
+<#list dateIntervalFunc.emptyStringToDateConversion as conversion>
+
+<@pp.changeOutputFile
name="/org/apache/drill/exec/expr/fn/impl/G${conversion.from}To${conversion.to}.java"
/>
+
+<#include "/@includes/license.ftl" />
+
+ package org.apache.drill.exec.expr.fn.impl;
+
+ import org.apache.drill.exec.expr.DrillSimpleFunc;
+ import org.apache.drill.exec.expr.annotations.FunctionTemplate;
+ import
org.apache.drill.exec.expr.annotations.FunctionTemplate.NullHandling;
+ import org.apache.drill.exec.expr.annotations.Output;
+ import org.apache.drill.exec.expr.annotations.Workspace;
+ import org.apache.drill.exec.expr.annotations.Param;
+ import org.apache.drill.exec.expr.holders.*;
+ import org.apache.drill.exec.record.RecordBatch;
+
+/*
+ * This class is generated using freemarker and the ${.template_name} template.
+ */
+@FunctionTemplate(name = "convert${conversion.from}To${conversion.to}", scope
= FunctionTemplate.FunctionScope.SIMPLE, nulls = NullHandling.INTERNAL)
Review comment:
- The function was introduced to handle input VarChar with possibility of
empty strings when `drill.exec.functions.cast_empty_string_to_null` is enabled.
The original function, such as `to_date` will be substituted with
`convertVarCharToDate` or `convertNullableVarCharToDate` depending on input
type mode (REQUIRED or OPTIONAL respectively) in a way it is done for `CAST`
functions.
- If null handling is NULL_IF_NULL then input NULLs are handled in a
generated code. In this case every input type mode is REQUIRED and it will not
work with literals.
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> Improve to_date, to_time and to_timestamp and corresponding cast functions to
> handle empty string when `drill.exec.functions.cast_empty_string_to_null`
> option is enabled
> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: DRILL-6768
> URL: https://issues.apache.org/jira/browse/DRILL-6768
> Project: Apache Drill
> Issue Type: Improvement
> Affects Versions: 1.14.0
> Reporter: Bohdan Kazydub
> Assignee: Bohdan Kazydub
> Priority: Major
> Labels: doc-impacting
> Fix For: 1.15.0
>
>
> When `drill.exec.functions.cast_empty_string_to_null` option is enabled
> `to_date`, `to_time` and `to_timestamp` functions while converting string to
> according type in case if null or empty string values are passed will return
> NULL (to avoid CASE clauses which are littering a query and will work in
> accordance with their respective CAST counterparts) for both cases.
>
>
>
> CASTs will be handled in a similar way (uniformly with numeric types):
>
> ||Value to cast||Now||Will be||
> |NULL|NULL|NULL|
> |'' (empty string)|Error in many cases (except numerical types)|NULL|
> CAST empty string to null (in case of enabled option) will be supported by
> DATE, TIME, TIMESTAMP, INTERVAL YEAR, INTERVAL MONTH and INTERVAL DAY
> functions in addition to numeric types.
>
> *For documentation*
> TBA
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