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https://issues.apache.org/jira/browse/DRILL-7293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16863791#comment-16863791
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ASF GitHub Bot commented on DRILL-7293:
---------------------------------------
arina-ielchiieva commented on pull request #1807: DRILL-7293: Convert the regex
("log") plugin to use EVF
URL: https://github.com/apache/drill/pull/1807#discussion_r293692425
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/store/log/README.md
##########
@@ -129,19 +129,62 @@ Drill 1.16 introduced the `CREATE SCHEMA` command to
allow you to define the
schema for your table. This plugin was created earlier. Here is how the two
schema
systems interact.
+### Plugin Config Provides Regex and Field Names
+
+The first way to use the provided schema is just to define column types.
+In this use case, the plugin config provides the physical layout (pattern
+and column names), the provided schema provides data types and default
+values (for missing columns.)
+
+In this case:
+
* The plugin config must provide the regex.
-* The plugin config should provide the list of column names. (If not provided,
+* The plugin config provides the list of column names. (If not provided,
the names will be `field_1`, `field_2`, etc.)
-* The plugin config can provide a type for each field. Text data from the regex
-is converted to a nullable column of the specified type.
-* The table can provide a schema via `CREATE SCHEMA`. If so, the column names
-in the schema must match those in the plugin config. The types in the provided
-schema are used instead of those specified in the plugin config. The schema
+* The plugin config should not provide column types.
+* The table provides a schema via `CREATE SCHEMA`. Column names
+in the schema must match those in the plugin config by name. The types in the
+provided schema are used instead of those specified in the plugin config. The
schema
allows you to specify the data type, and either nullable or `not null`
cardinality.
-You may find it helpful to specify the regex and column names via the plugin
-config, types via the `CREATE SCHEMA` command.
+### Provided Schema Provides The Regex
+
+Another way to use the provided schema is to define an empty plugin config;
don't
+even provide the regex. Use table properties to define the regex (and the
maximum
+error count, if desired.)
+
+In this case:
+
+* Set the table property `drill.regex.regex` to the desired pattern.
Review comment:
I think we should use different naming, `drill.regex.regex` look awkward.
Maybe `drill.regex.pattern` or something like this?
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> Convert the regex ("log") plugin to use EVF
> -------------------------------------------
>
> Key: DRILL-7293
> URL: https://issues.apache.org/jira/browse/DRILL-7293
> Project: Apache Drill
> Issue Type: Improvement
> Affects Versions: 1.16.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Major
> Fix For: 1.17.0
>
>
> The "log" plugin (which uses a regex to define the row format) is the subject
> of Chapter 12 of the Learning Apache Drill book (though the version in the
> book is simpler than the one in the master branch.)
> The recently-completed "Enhanced Vector Framework" (EVF, AKA the "row set
> framework") gives Drill control over the size of batches created by readers,
> and allows readers to use the recently-added provided schema mechanism.
> We wish to use the log reader as an example for how to convert a Drill format
> plugin to use the EVF so that other developers can convert their own plugins.
> This PR provides the first set of log plugin changes to enable us to publish
> a tutorial on the EVF.
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