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Posted to commits@calcite.apache.org by jh...@apache.org on 2016/06/13 07:54:02 UTC
[2/3] calcite git commit: Improve Druid documentation
Improve Druid documentation
Project: http://git-wip-us.apache.org/repos/asf/calcite/repo
Commit: http://git-wip-us.apache.org/repos/asf/calcite/commit/56b753df
Tree: http://git-wip-us.apache.org/repos/asf/calcite/tree/56b753df
Diff: http://git-wip-us.apache.org/repos/asf/calcite/diff/56b753df
Branch: refs/heads/master
Commit: 56b753df4a2e6b971720333e0fc2bef4719d50ac
Parents: 0c58243
Author: Julian Hyde <jh...@apache.org>
Authored: Fri Jun 10 16:56:49 2016 -0700
Committer: Julian Hyde <jh...@apache.org>
Committed: Mon Jun 13 00:29:21 2016 -0700
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site/_docs/druid_adapter.md | 102 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 101 insertions(+), 1 deletion(-)
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http://git-wip-us.apache.org/repos/asf/calcite/blob/56b753df/site/_docs/druid_adapter.md
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diff --git a/site/_docs/druid_adapter.md b/site/_docs/druid_adapter.md
index 9de2fb9..d45caba 100644
--- a/site/_docs/druid_adapter.md
+++ b/site/_docs/druid_adapter.md
@@ -140,7 +140,7 @@ sqlline>
{% endhighlight %}
That query shows the top 5 countries of origin of wiki page edits
-on 2015-09-12 (the date covered by the wikiticker data set).
+on 2015-09-12 (the date covered by the `wikiticker` data set).
Now let's see how the query was evaluated:
@@ -173,3 +173,103 @@ into a single Druid data set called "foodmart".
You can access it via the
`druid/src/test/resources/druid-foodmart-model.json` model.
+
+# Simplifying the model
+
+If less metadata is provided in the model, the Druid adapter can discover
+it automatically from Druid. Here is a schema equivalent to the previous one
+but with `dimensions`, `metrics` and `timestampColumn` removed:
+
+{% highlight json %}
+{
+ "version": "1.0",
+ "defaultSchema": "wiki",
+ "schemas": [
+ {
+ "type": "custom",
+ "name": "wiki",
+ "factory": "org.apache.calcite.adapter.druid.DruidSchemaFactory",
+ "operand": {
+ "url": "http://localhost:8082",
+ "coordinatorUrl": "http://localhost:8081"
+ },
+ "tables": [
+ {
+ "name": "wiki",
+ "factory": "org.apache.calcite.adapter.druid.DruidTableFactory",
+ "operand": {
+ "dataSource": "wikiticker",
+ "interval": "1900-01-09T00:00:00.000Z/2992-01-10T00:00:00.000Z"
+ }
+ }
+ ]
+ }
+ ]
+}
+{% endhighlight %}
+
+Calcite dispatches a
+[segmentMetadataQuery](http://druid.io/docs/latest/querying/segmentmetadataquery.html)
+to Druid to discover the columns of the table.
+Now, let's take out the `tables` element:
+
+{% highlight json %}
+{
+ "version": "1.0",
+ "defaultSchema": "wiki",
+ "schemas": [
+ {
+ "type": "custom",
+ "name": "wiki",
+ "factory": "org.apache.calcite.adapter.druid.DruidSchemaFactory",
+ "operand": {
+ "url": "http://localhost:8082",
+ "coordinatorUrl": "http://localhost:8081"
+ }
+ }
+ ]
+}
+{% endhighlight %}
+
+Calcite discovers the "wikiticker" data source via the
+[/druid/coordinator/v1/metadata/datasources](http://druid.io/docs/latest/design/coordinator.html#metadata-store-information)
+REST call. Now that the "wiki" table element is removed, the table is called
+"wikiticker". Any other data sources present in Druid will also appear as
+tables.
+
+Our model is now a single schema based on a custom schema factory with only two
+operands, so we can
+[dispense with the model](https://issues.apache.org/jira/browse/CALCITE-1206)
+and supply the operands as part of the connect string:
+
+{% highlight bash %}
+ jdbc:calcite:schemaFactory=org.apache.calcite.adapter.druid.DruidSchemaFactory; schema.url=http://localhost:8082; schema.coordinatorUrl=http://localhost:8081
+{% endhighlight %}
+
+In fact, those are the
+[default values of the operands]({{ site.apiRoot }}/org/apache/calcite/adapter/druid/DruidSchemaFactory.html),
+so we can omit them:
+
+{% highlight bash %}
+ jdbc:calcite:schemaFactory=org.apache.calcite.adapter.druid.DruidSchemaFactory
+{% endhighlight %}
+
+Now, we can connect to `sqlline` using a very simple connect string, and list
+the available tables:
+
+{% highlight bash %}
+$ ./sqlline
+sqlline> !connect jdbc:calcite:schemaFactory=org.apache.calcite.adapter.druid.DruidSchemaFactory admin admin
+sqlline> !tables
++-----------+-------------+------------+--------------+
+| TABLE_CAT | TABLE_SCHEM | TABLE_NAME | TABLE_TYPE |
++-----------+-------------+------------+--------------+
+| | adhoc | foodmart | TABLE |
+| | adhoc | wikiticker | TABLE |
+| | metadata | COLUMNS | SYSTEM_TABLE |
+| | metadata | TABLES | SYSTEM_TABLE |
++-----------+-------------+------------+--------------+
+{% endhighlight %}
+
+We see the two system tables (`TABLES` and `COLUMNS`),
+and the two tables in Druid (`foodmart` and `wikiticker`).