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https://issues.apache.org/jira/browse/DRILL-7293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16873852#comment-16873852
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ASF GitHub Bot commented on DRILL-7293:
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paul-rogers commented on issue #1807: DRILL-7293: Convert the regex ("log")
plugin to use EVF
URL: https://github.com/apache/drill/pull/1807#issuecomment-506209593
@arina-ielchiieva, added a unit test to show that the schema-only table
function works.
Tried to create a test that combined a "plugin" table function with the
"schema" attribute. This failed due to the unfortunate use of "schema" as
plugin property name. You've pointed out this issue all along, I finally
understood why it was a problem. Still, I'm reluctant to change the config
property name for fear of breaking compatibility.
As it turns out, this limitation is only a minor nuisance since the only
reason to combine the two kinds of table functions is to specify the regex
property. A unit test shows that the regex can be specified as a table property
instead.
Also, went ahead and added support for the `columns` column. If no schema is
provided (not in the plugin config, not in a table function, not in a provided
schema), then rather than creating a set of dummy fields `field_0`, `field_1`,
etc., the plugin how follows the text format plugin and puts the fields into
the `columns` array. The dummy fields are still used if the user specifies at
least one column schema, but the regex has more groups than specified columns.
This means that, if the user uses a table function to specify just the
regex, the user gets a reasonable result: the fields come back in the `columns`
array.
Unit tests show the new `columns` array support.
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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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