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https://issues.apache.org/jira/browse/FLINK-32721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17783908#comment-17783908
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Yao Zhang commented on FLINK-32721:
-----------------------------------
Hi Community,
It seems that there is a contradiction in what CHAR means in Flink. Char type
in SQL means a fixed-length string but in
org.apache.flink.api.common.typeinfo.Types.CHAR is a single character with the
type of java.lang.Character in Java.
Based on this in order to test max aggretation function with type 'char' in
unit test
org/apache/flink/table/planner/plan/stream/sql/agg/AggregateTest.scala, we
should not define another filed with "Types.{color:#c77dbb}CHAR"
{color}{color:#172b4d}as it stands for a single character. The only
{color:#172b4d}representation{color} of "char" type in SQL in
org.apache.flink.api.common.typeinfo.Types is STRING.
{color}
> agg max/min supports char type
> ------------------------------
>
> Key: FLINK-32721
> URL: https://issues.apache.org/jira/browse/FLINK-32721
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / Planner
> Affects Versions: 1.18.0
> Reporter: Jacky Lau
> Assignee: Jacky Lau
> Priority: Major
> Labels: pull-request-available, stale-assigned
> Fix For: 1.19.0
>
>
> {code:java}
> // flink
> Flink SQL> CREATE TABLE Orders (
> > name char(10),
> > price DECIMAL(32,2),
> > buyer ROW<first_name STRING, last_name STRING>,
> > order_time TIMESTAMP(3)
> > ) WITH (
> > 'connector' = 'datagen'
> > );
> [INFO] Execute statement succeed.
> Flink SQL> select max(name) from Orders;
> [ERROR] Could not execute SQL statement. Reason:
> org.apache.flink.table.api.TableException: Max aggregate function does not
> support type: ''CHAR''.
> Please re-check the data type. {code}
> {code:java}
> // mysql
> CREATE TABLE IF NOT EXISTS `docs` (
> `id` int(6) unsigned NOT NULL,
> `rev` int(3) unsigned NOT NULL,
> `content` char(200) NOT NULL,
> PRIMARY KEY (`id`,`rev`)
> ) DEFAULT CHARSET=utf8;
> INSERT INTO `docs` (`id`, `rev`, `content`) VALUES
> ('1', '1', 'The earth is flat'),
> ('2', '1', 'One hundred angels can dance on the head of a pin'),
> ('1', '2', 'The earth is flat and rests on a bull\'s horn'),
> ('1', '3', 'The earth is like a ball.');
> select max(content) from docs;
> // result
> |max(content)|
> The earth is like a ball.{code}
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