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Subject [GitHub] [drill] vvysotskyi commented on a change in pull request #1986: Additional changes for Drill Metastore docs
Date Tue, 03 Mar 2020 15:29:38 GMT
vvysotskyi commented on a change in pull request #1986: Additional changes for Drill Metastore
docs
URL: https://github.com/apache/drill/pull/1986#discussion_r386537049
 
 

 ##########
 File path: _docs/performance-tuning/drill-metastore/010-using-drill-metastore.md
 ##########
 @@ -48,42 +83,52 @@ drill.metastore: {
 }
 ```
 
-Note, that currently out of box Iceberg Metastore is available and is the default one. Though
any custom
- implementation can be added by placing the JAR into classpath which has the implementation
of
- `org.apache.drill.metastore.Metastore` interface and indicating custom class in the `drill.metastore.implementation.class`.
-
 ### Metastore Components
 
-Metastore can store metadata for various components: tables, views, etc.
-Current implementation provides fully functioning support for tables component.
-Views component support is not implemented but contains stub methods to show
-how new Metastore components like UDFs, storage plugins, etc. can be added in the future.
+The Drill 1.17 version of the Metastore stores metadata about tables: the table schema and
table statistics.
+The Metastore is an active subproject of Drill, See [DRILL-6552](https://issues.apache.org/jira/browse/DRILL-6552)
for more information.
+
+### Table Metadata
+
+Table Metadata includes the following info:
+
+ - Table schema, column name, type, nullability, scale and precision if available, and other
info. For details please
+  refer to [Schema provisioning]({{site.baseurl}}/docs/create-or-replace-schema/#usage-notes).
+ - Table statistics. This itself has two categories:
+    - Summary statistics: `MIN`, `MAX`, `NULL count`, etc.
+    - Detail statistics: histograms, `NDV`, etc.
 
-### Metastore Tables
+Schema information and summary statistics also computed and stored for table segments, files,
row groups, partitions.
 
 Review comment:
   Thanks, removed comma.

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