bbevens closed pull request #1474: DRILL-6749: Fixing broken links to CTAS and
Explain Commands
URL: https://github.com/apache/drill/pull/1474
This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:
As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):
diff --git a/_docs/performance-tuning/026-parquet-filter-pushdown.md
b/_docs/performance-tuning/026-parquet-filter-pushdown.md
index 466f0830a85..0afdcee561f 100644
--- a/_docs/performance-tuning/026-parquet-filter-pushdown.md
+++ b/_docs/performance-tuning/026-parquet-filter-pushdown.md
@@ -24,7 +24,7 @@ Parquet filter pushdown is similar to partition pruning in
that it reduces the a
The query planner looks at the minimum and maximum values in each row group
for an intersection. If no intersection exists, the planner can prune the row
group in the table. If the minimum and maximum value range is too large, Drill
does not apply Parquet filter pushdown. The query planner can typically prune
more data when the tables in the Parquet file are sorted by row groups.
##Using Parquet Filter Pushdown
-Currently, Parquet filter pushdown only supports filters that reference
columns from a single table (local filters). Parquet filter pushdown requires
the minimum and maximum values in the Parquet file metadata. All Parquet files
created in Drill using the CTAS statement contain the necessary metadata. If
your Parquet files were created using another tool, you may need to use Drill
to read and rewrite the files using the [CTAS
command]({{site.baseurl}}/docs/create-table-as-ctas-command/).
+Currently, Parquet filter pushdown only supports filters that reference
columns from a single table (local filters). Parquet filter pushdown requires
the minimum and maximum values in the Parquet file metadata. All Parquet files
created in Drill using the CTAS statement contain the necessary metadata. If
your Parquet files were created using another tool, you may need to use Drill
to read and rewrite the files using the [CTAS
command]({{site.baseurl}}/docs/create-table-as-ctas/).
Parquet filter pushdown works best if you presort the data. You do not have to
sort the entire data set at once. You can sort a subset of the data set, sort
another subset, and so on.
@@ -39,7 +39,7 @@ The following table lists the Parquet filter pushdown options
with their descrip
| "planner.store.parquet.rowgroup.filter.pushdown.threshold" | Sets the number
of row groups that a table can have. You can increase the threshold if the
filter can prune many row groups. However, if this setting is too high, the
filter evaluation overhead increases. Base this setting on the data set.
Reduce this setting if the planning time is significant, or you do not see
any benefit at runtime. | 10,000 |
###Viewing the Query Plan
-Because Drill applies Parquet filter pushdown during the query planning phase,
you can view the query execution plan to see if Drill pushes down the filter
when a query on a Parquet file contains a filter expression. You can run the
[EXPLAIN PLAN command]({{site.baseurl}}/docs/explain-commands/) to see the
execution plan for the query, as shown in the following example.
+Because Drill applies Parquet filter pushdown during the query planning phase,
you can view the query execution plan to see if Drill pushes down the filter
when a query on a Parquet file contains a filter expression. You can run the
[EXPLAIN PLAN command]({{site.baseurl}}/docs/explain/) to see the execution
plan for the query, as shown in the following example.
**Example**
@@ -79,4 +79,4 @@ The following table lists the supported and unsupported
clauses, operators, data
- a dynamic star in the sub-query or queries that include the WITH statement.
- several filter predicates with the OR logical operator.
- more than one EXISTS operator (instead of JOIN operators).
-- INNER JOIN and local filtering with a several conditions.
\ No newline at end of file
+- INNER JOIN and local filtering with a several conditions.
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
With regards,
Apache Git Services
