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Posted to issues@drill.apache.org by "Jacques Nadeau (JIRA)" <ji...@apache.org> on 2015/03/26 03:35:53 UTC
[jira] [Commented] (DRILL-2568) New partition pruning prevents the
optimization for trivial COUNT(*) queries
[ https://issues.apache.org/jira/browse/DRILL-2568?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14381248#comment-14381248 ]
Jacques Nadeau commented on DRILL-2568:
---------------------------------------
Can you please post review board?
> New partition pruning prevents the optimization for trivial COUNT(*) queries
> ----------------------------------------------------------------------------
>
> Key: DRILL-2568
> URL: https://issues.apache.org/jira/browse/DRILL-2568
> Project: Apache Drill
> Issue Type: Bug
> Components: Query Planning & Optimization
> Affects Versions: 0.8.0
> Reporter: Aman Sinha
> Assignee: Aman Sinha
> Attachments: 0001-DRILL-2568-Drop-filter-plan-node-if-all-conjuncts-ha.patch
>
>
> With the new interpreter based partition pruning, if the query has only partition filters and they are pushed into the Scan, we don't drop the Filter node from the plan. This prevents the optimization for COUNT(*) queries against parquet files where we read the count values directly from the parquet files instead of scanning and aggregating. The ConvertCountToDirectScan rule does not get applied if there is an intervening Filter between the Scan and the Aggregate nodes.
> {code}
> 0: jdbc:drill:zk=local> explain plan for select count(*) from dfs.`/Users/asinha/data/multilevel/parquet` where dir0=1995;
> +------------+------------+
> | text | json |
> +------------+------------+
> | 00-00 Screen
> 00-01 StreamAgg(group=[{}], EXPR$0=[COUNT()])
> 00-02 Project($f0=[0])
> 00-03 SelectionVectorRemover
> 00-04 Filter(condition=[=($0, 1995)])
> 00-05 Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=file:/Users/asinha/data/multilevel/parquet/1995/Q1/orders_95_q1.parquet], ReadEntryWithPath [path=file:/Users/asinha/data/multilevel/parquet/1995/Q2/orders_95_q2.parquet], ReadEntryWithPath [path=file:/Users/asinha/data/multilevel/parquet/1995/Q3/orders_95_q3.parquet], ReadEntryWithPath [path=file:/Users/asinha/data/multilevel/parquet/1995/Q4/orders_95_q4.parquet]], selectionRoot=/Users/asinha/data/multilevel/parquet, numFiles=4, columns=[`dir0`]]])
> {code}
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