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Subject [GitHub] pnowojski commented on a change in pull request #6897: [FLINK-9737] [FLINK-8880] [sql-client] Support defining temporal tables in environment files
Date Tue, 23 Oct 2018 08:01:04 GMT
pnowojski commented on a change in pull request #6897: [FLINK-9737] [FLINK-8880] [sql-client]
Support defining temporal tables in environment files
URL: https://github.com/apache/flink/pull/6897#discussion_r227267053
 
 

 ##########
 File path: docs/dev/table/sqlClient.md
 ##########
 @@ -503,7 +504,49 @@ Views created within a CLI session can also be removed again using the
`DROP VIE
 DROP VIEW MyNewView;
 {% endhighlight %}
 
-<span class="label label-danger">Attention</span> The definition of views is
limited to the mentioned syntax above. Defining a schema for views or escape whitespaces in
table names will be supported in future versions.
+<span class="label label-danger">Attention</span> The definition of views in
the CLI is limited to the mentioned syntax above. Defining a schema for views or escaping
whitespaces in table names will be supported in future versions.
+
+{% top %}
+
+Temporal Tables
+---------------
+
+A [temporal table](./streaming/temporal_tables.html) allows for a (parameterized) view on
a changing history table that returns the content of a table at a specific point in time.
This is especially useful for joining a table with the content of another table at a particular
timestamp. More information can be found in the [temporal table joins](./streaming/joins.html#join-with-a-temporal-table)
page.
+
+The following example shows how to define a temporal table `SourceTemporalTable`:
+
+{% highlight yaml %}
+tables:
+
+  # Define the table source (or view) that contains updates to a temporal table
+  - name: HistorySource
+    type: source-table
+    update-mode: append
+    connector: # ...
+    format: # ...
+    schema:
+      - name: integerField
+        type: INT
+      - name: stringField
+        type: VARCHAR
+      - name: rowtimeField
+        type: TIMESTAMP
+        rowtime:
+          timestamps:
+            type: from-field
+            from: rowtimeField
+          watermarks:
+            type: from-source
+
+  # Define a temporal table over the changing history table with time attribute and primary
key
+  - name: SourceTemporalTable
+    type: temporal-table
+    changing-table: HistorySource
 
 Review comment:
   `changing-table` is not very good name and it's inconsistent with already used nomenclature,
that even you are using here :) (`History***`). Maybe change it to `underlying-table`, `underlying-history-table`,
`history-table` or something like that? If you think that there is some better name, please
also make the effort to rename existing `underlyingHistoryTable` occurrences in the source
code.

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