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From "Khurram Faraaz (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DRILL-3419) Handle scans optimally when all files are pruned out
Date Thu, 08 Oct 2015 18:22:26 GMT

     [ https://issues.apache.org/jira/browse/DRILL-3419?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Khurram Faraaz updated DRILL-3419:
----------------------------------
    Fix Version/s:     (was: Future)
                   1.3.0

> Handle scans optimally when all files are pruned out
> ----------------------------------------------------
>
>                 Key: DRILL-3419
>                 URL: https://issues.apache.org/jira/browse/DRILL-3419
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>    Affects Versions: 1.1.0
>            Reporter: Khurram Faraaz
>             Fix For: 1.3.0
>
>
> Note that in case (1) and case (2) we prune, however it is not clear if we prune is case
(3), that is because we see a FILTER in the query plan in case (3)
> CTAS 
> {code}
> 0: jdbc:drill:schema=dfs.tmp> CREATE TABLE CTAS_ONE_MILN_RWS_PER_GROUP(col1, col2)
PARTITION BY (col2) AS select cast(columns[0] as bigint) col1, cast(columns[1] as char(2))
col2 from `millionValGroup.csv`;
> +-----------+----------------------------+
> | Fragment  | Number of records written  |
> +-----------+----------------------------+
> | 1_1       | 21932064                   |
> | 1_0       | 28067936                   |
> +-----------+----------------------------+
> 2 rows selected (73.661 seconds)
> {code}
> case 1)
> {code}
> explain plan for select col1, col2 from CTAS_ONE_MILN_RWS_PER_GROUP where col2 LIKE '%Z%';
> | 00-00    Screen
> 00-01      Project(col1=[$0], col2=[$1])
> 00-02        UnionExchange
> 01-01          Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_0_3.parquet],
ReadEntryWithPath [path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_1_3.parquet]], selectionRoot=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP,
numFiles=2, columns=[`col2`, `col1`]]])
> {code}
> case 2)
> {code}
> explain plan for select col1, col2 from CTAS_ONE_MILN_RWS_PER_GROUP where col2 LIKE 'A%';
> | 00-00    Screen
> 00-01      Project(col1=[$0], col2=[$1])
> 00-02        UnionExchange
> 01-01          Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_0_3.parquet],
ReadEntryWithPath [path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_0_2.parquet], ReadEntryWithPath
[path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_1_1.parquet], ReadEntryWithPath [path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_1_2.parquet],
ReadEntryWithPath [path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_1_3.parquet], ReadEntryWithPath
[path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_0_1.parquet]], selectionRoot=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP,
numFiles=6, columns=[`col2`, `col1`]]])
> {code}
> case 3) we are NOT pruning here.
> {code}
> explain plan for select col1, col2 from CTAS_ONE_MILN_RWS_PER_GROUP where col2 LIKE 'Z%';
> | 00-00    Screen
> 00-01      Project(col1=[$1], col2=[$0])
> 00-02        SelectionVectorRemover
> 00-03          Filter(condition=[LIKE($0, 'Z%')])
> 00-04            Project(col2=[$1], col1=[$0])
> 00-05              Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP/1_1_48.parquet]],
selectionRoot=/tmp/CTAS_ONE_MILN_RWS_PER_GROUP, numFiles=1, columns=[`col2`, `col1`]]])
> {code}



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