JingsongLi commented on a change in pull request #13010:
URL: https://github.com/apache/flink/pull/13010#discussion_r468310256
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File path: docs/dev/table/connectors/datagen.md
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@@ -29,25 +29,24 @@ under the License.
* This will be replaced by the TOC
{:toc}
-The DataGen connector allows for reading by data generation rules.
+The DataGen connector allows for creating tables based on in-memory data
generation.
+This is useful when developing queries locally without access to external
systems such as Kafka.
+Tables can include [Computed Column syntax]({% link dev/table/sql/create.md
%}#create-table) which allows for flexible record generation.
-The DataGen connector can work with [Computed Column syntax]({% link
dev/table/sql/create.md %}#create-table).
-This allows you to generate records flexibly.
+The DataGen connector is built-in, no additional dependencies are required.
-The DataGen connector is built-in.
+Usage
+-----
-<span class="label label-danger">Attention</span> Complex types are not
supported: Array, Map, Row. Please construct these types by computed column.
+By default, a DataGen table will create an unbounded number of rows with a
random value for each column.
+For variable sized types, char/varchar/string/array/map/multiset, the length
can be specified.
+Additionally, a total number of rows can be specified, resulting in a bounded
table.
-How to create a DataGen table
-----------------
-
-The boundedness of table: when the generation of field data in the table is
completed, the reading
-is finished. So the boundedness of the table depends on the boundedness of
fields.
-
-For each field, there are two ways to generate data:
+There also exists a sequence generator, where users specify a sequence of
start and end values.
+Complex types cannot be generated as a sequence.
+If any column in a table is a sequence type, the table will be bounded and end
with the first sequence completes.
-- Random generator is the default generator, you can specify random max and
min values. For char/varchar/string, the length can be specified. It is a
unbounded generator.
-- Sequence generator, you can specify sequence start and end values. It is a
bounded generator, when the sequence number reaches the end value, the reading
ends.
+Time types are always the local machines current system time.
Review comment:
Maybe we can have a table to show all types.
Display the generation strategies they support, and the required parameters?
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