leonardBang commented on a change in pull request #9545: [FLINK-13355][docs]
Add documentation for Temporal Table Join in blink planner
URL: https://github.com/apache/flink/pull/9545#discussion_r318987035
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File path: docs/dev/table/streaming/temporal_tables.md
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@@ -78,9 +82,36 @@ The concept of *Temporal Tables* aims to simplify such
queries, speed up their e
In the above example `currency` would be a primary key for `RatesHistory`
table and `rowtime` would be the timestamp attribute.
-In Flink, a temporal table is represented by a *Temporal Table Function*.
+In Flink, this is represented by a *Temporal Table Function*.
+
+On the other hand, we have the requirement to join a changing dimension table
which is an external database table.
+
+Let's assume that we have a table `LatestRates` (e.g. stored in MySQL table)
that is materialized with the latest rate. The `LatestRates` is the
materialized history `RatesHistory`. Then the content of `LatestRates` table at
time `10:58` will be:
+
+{% highlight text %}
+10:58> SELECT * FROM LatestRates;
+currency rate
+======== ======
+US Dollar 102
+Yen 1
+Euro 116
+{% endhighlight %}
-Temporal Table Functions
+The content of `LatestRates` table at time `12:00` will be:
+
+{% highlight text %}
+12:00> SELECT * FROM LatestRates;
+currency rate
+======== ======
+US Dollar 102
+Yen 1
+Euro 119
+Pounds 108
+{% endhighlight %}
+
+In Flink, this is represented by a *Temporal Table*. Note that, in the future,
the *Temporal Table* can also represents the changing history table
`RetesHistory`.
+
Review comment:
"can also **represents**"->"can also **represent**"
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