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https://issues.apache.org/jira/browse/FLINK-6693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16060701#comment-16060701
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ASF GitHub Bot commented on FLINK-6693:
---------------------------------------
Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/4078#discussion_r123718165
--- Diff:
flink-libraries/flink-table/src/main/java/org/apache/flink/table/runtime/DateTimeFunctions.java
---
@@ -0,0 +1,158 @@
+/*
+ * 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.flink.table.runtime;
+
+import org.joda.time.format.DateTimeFormatter;
+import org.joda.time.format.DateTimeFormatterBuilder;
+
+/**
+ * Built-in scalar functions for date time related operations.
+ */
+public class DateTimeFunctions {
+ private static final int PIVOT_YEAR = 2020;
+
+ private static final ThreadLocalCache<String, DateTimeFormatter>
DATETIME_FORMATTER_CACHE =
+ new ThreadLocalCache<String, DateTimeFormatter>(100) {
+ @Override
+ protected DateTimeFormatter getNewInstance(String
format) {
+ return createDateTimeFormatter(format);
+ }
+ };
+
+ public static String dateFormat(long ts, String formatString) {
+ DateTimeFormatter formatter =
DATETIME_FORMATTER_CACHE.get(formatString);
--- End diff --
I recently added a `literal` flag to generated expressions. So we can check
if the parameters of a constructor are constant (see `RandCallGen`). Would be
great if you could also change `RandCallGen` to use the ThreadLocalCache if
seed is not constant.
> Support DATE_FORMAT function in the Table / SQL API
> ---------------------------------------------------
>
> Key: FLINK-6693
> URL: https://issues.apache.org/jira/browse/FLINK-6693
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: Haohui Mai
> Assignee: Haohui Mai
>
> It would be quite handy to support the {{DATE_FORMAT}} function in Flink to
> support various date / time related operations:
> The specification of the {{DATE_FORMAT}} function can be found in
> https://prestodb.io/docs/current/functions/datetime.html.
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