paul-rogers commented on a change in pull request #2030: Update docs for
Metastore to point that all format plugins are supported
URL: https://github.com/apache/drill/pull/2030#discussion_r394552697
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File path:
_docs/performance-tuning/drill-metastore/010-using-drill-metastore.md
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@@ -117,6 +119,14 @@ Drill can connect to any number of data sources, each of
which may have its own
As a result, the Metastore labels tables with a combination of (plugin
configuration name, workspace name, table name).
Note that if before renaming any of these items, you must delete table's
Metadata entry and recreate it after renaming.
+### Using schema provisioning feature with Drill Metastore
+
+Drill Metastore allows specifying schema using the same syntax as
+ [Schema
provisioning]({{site.baseurl}}/docs/plugin-configuration-basics/#specifying-the-schema-as-table-function-parameter)
feature when used as a table function.
+User can specify table schema in the `ANALYZE` command, so it will be used for
collecting table statistics and will be stored
+ to Drill Metastore to be used when submitting queries for this table similar
to the case when user specifies schema
+ explicitly in the table function.
Review comment:
The Drill Metastore holds both schema and statistics information for a
table. The `ANALYZE` command can infer the table schema for well-defined tables
(such as many Parquet tables). Some tables are too complex or variable for
Drill's schema inference to work well. For example, JSON tables often omit
fields or have long runs of nulls so that Drill cannot determine column types.
In these cases you can specify the correct schema based on your knowledge of
the a table's structure. You specify a schema in the `ANALYZE` command using
the
[Schema
provisioning]({{site.baseurl}}/docs/plugin-configuration-basics/#specifying-the-schema-as-table-function-parameter)
syntax.
(Please provide an example.)
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