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https://issues.apache.org/jira/browse/DRILL-6768?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16642435#comment-16642435
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ASF GitHub Bot commented on DRILL-6768:
---------------------------------------
vdiravka 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_r223477424
##########
File path:
logical/src/main/java/org/apache/drill/common/expression/fn/ToFunctions.java
##########
@@ -0,0 +1,130 @@
+/*
+ * 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.drill.common.expression.fn;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.drill.common.types.TypeProtos.DataMode;
+import org.apache.drill.common.types.TypeProtos.MinorType;
+
+public class ToFunctions {
+
+ private static Map<MinorType, String> TO_FUNC = new HashMap<>();
+ /** The to functions that need to be replaced (if
+ * "drill.exec.functions.cast_empty_string_to_null" is set to true). */
+ private static Set<String> TO_FUNC_REPLACEMENT_NEEDED = new HashSet<>();
+ /** Map from the replaced functions to the new ones (for non-nullable
VARCHAR). */
+ private static Map<String, String> FUNC_REPLACEMENT_FROM_NONNULLABLE_VARCHAR
= new HashMap<>();
+ /** Map from the replaced functions to the new ones (for non-nullable
VAR16CHAR). */
+ private static Map<String, String>
FUNC_REPLACEMENT_FROM_NONNULLABLE_VAR16CHAR = new HashMap<>();
+ /** Map from the replaced functions to the new ones (for non-nullable
VARBINARY). */
+ private static Map<String, String>
FUNC_REPLACEMENT_FROM_NONNULLABLE_VARBINARY = new HashMap<>();
+ /** Map from the replaced functions to the new ones (for nullable VARCHAR).
*/
+ private static Map<String, String> FUNC_REPLACEMENT_FROM_NULLABLE_VARCHAR =
new HashMap<>();
+ /** Map from the replaced functions to the new ones (for nullable
VAR16CHAR). */
+ private static Map<String, String> FUNC_REPLACEMENT_FROM_NULLABLE_VAR16CHAR
= new HashMap<>();
+ /** Map from the replaced functions to the new ones (for nullable
VARBINARY). */
+ private static Map<String, String> FUNC_REPLACEMENT_FROM_NULLABLE_VARBINARY
= new HashMap<>();
+
+ static {
+ TO_FUNC.put(MinorType.DATE, "to_date");
+ TO_FUNC.put(MinorType.TIME, "to_time");
+ TO_FUNC.put(MinorType.TIMESTAMP, "to_timestamp");
+
+ setupReplacementFunctions(MinorType.DATE, "NullableDate");
+ setupReplacementFunctions(MinorType.TIME, "NullableTime");
+ setupReplacementFunctions(MinorType.TIMESTAMP, "NullableTimeStamp");
+ }
+
+ private static void setupReplacementFunctions(MinorType type, String toType)
{
+ String functionName = TO_FUNC.get(type);
+
+ TO_FUNC_REPLACEMENT_NEEDED.add(functionName);
+
+ FUNC_REPLACEMENT_FROM_NONNULLABLE_VARCHAR.put(functionName,
"convertVarCharTo" + toType);
+ FUNC_REPLACEMENT_FROM_NONNULLABLE_VAR16CHAR.put(functionName,
"convertVar16CharTo" + toType);
+ FUNC_REPLACEMENT_FROM_NONNULLABLE_VARBINARY.put(functionName,
"convertVarBinaryTo" + toType);
+ FUNC_REPLACEMENT_FROM_NULLABLE_VARCHAR.put(functionName,
"convertNullableVarCharTo" + toType);
+ FUNC_REPLACEMENT_FROM_NULLABLE_VAR16CHAR.put(functionName,
"convertNullableVar16CharTo" + toType);
+ FUNC_REPLACEMENT_FROM_NULLABLE_VARBINARY.put(functionName,
"convertNullableVarBinaryTo" + toType);
+ }
+
+ /**
+ * Get a replacing to_ function for the original function, based on the
specified data mode. Should be used
+ * iff {@link #isReplacementNeeded(String, MinorType)} returns {@code true}.
+ *
+ * @param functionName original function name
+ * @param dataMode data mode of the input data
+ * @param inputType input (minor) type
+ * @return the name of replaced function
+ */
+ public static String getReplacingFunction(String functionName, DataMode
dataMode, MinorType inputType) {
+ if(dataMode == DataMode.OPTIONAL) {
+ return getReplacingFunctionFromNullable(functionName, inputType);
+ }
+
+ if(dataMode == DataMode.REQUIRED) {
+ return getReplacingFunctionFromNonNullable(functionName, inputType);
+ }
+
+ throw new RuntimeException(String.format("replacing to function for data
mode %s is not defined", dataMode));
+ }
+
+ /**
+ * Check if a replacing to function is available for the the original
function
+ * @param functionName original to function
+ * @param inputType input (minor) type for to
+ * @return {@code true} if replacement is needed, {@code false} otherwise
+ */
+ public static boolean isReplacementNeeded(String functionName, MinorType
inputType) {
+ return (inputType == MinorType.VARCHAR || inputType == MinorType.VARBINARY
|| inputType == MinorType.VAR16CHAR)
+ && TO_FUNC_REPLACEMENT_NEEDED.contains(functionName);
+ }
+
+ private static String getReplacingFunctionFromNonNullable(String
functionName, MinorType inputType) {
+ if(inputType == MinorType.VARCHAR &&
FUNC_REPLACEMENT_FROM_NONNULLABLE_VARCHAR.containsKey(functionName)) {
+ return FUNC_REPLACEMENT_FROM_NONNULLABLE_VARCHAR.get(functionName);
+ }
+ if(inputType == MinorType.VAR16CHAR &&
FUNC_REPLACEMENT_FROM_NONNULLABLE_VAR16CHAR.containsKey(functionName)) {
+ return FUNC_REPLACEMENT_FROM_NONNULLABLE_VAR16CHAR.get(functionName);
+ }
+ if(inputType == MinorType.VARBINARY &&
FUNC_REPLACEMENT_FROM_NONNULLABLE_VARBINARY.containsKey(functionName)) {
+ return FUNC_REPLACEMENT_FROM_NONNULLABLE_VARBINARY.get(functionName);
+ }
+
+
+ throw new RuntimeException(String.format("replacing to_ function for %s is
not defined", functionName));
+ }
+
+ private static String getReplacingFunctionFromNullable(String functionName,
MinorType inputType) {
+ if(inputType == MinorType.VARCHAR &&
FUNC_REPLACEMENT_FROM_NULLABLE_VARCHAR.containsKey(functionName)) {
+ return FUNC_REPLACEMENT_FROM_NULLABLE_VARCHAR.get(functionName);
+ }
+ if(inputType == MinorType.VAR16CHAR &&
FUNC_REPLACEMENT_FROM_NULLABLE_VAR16CHAR.containsKey(functionName)) {
+ return FUNC_REPLACEMENT_FROM_NULLABLE_VAR16CHAR.get(functionName);
+ }
+ if(inputType == MinorType.VARBINARY &&
FUNC_REPLACEMENT_FROM_NULLABLE_VARBINARY.containsKey(functionName)) {
+ return FUNC_REPLACEMENT_FROM_NULLABLE_VARBINARY.get(functionName);
+ }
+
+ throw new RuntimeException(String.format("replacing to_ function for %s is
not defined", functionName));
Review comment:
`DrillRunTimeException`
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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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