[jira] [Assigned] (IMPALA-6625) Skip dictionary and collection conjunct assignment for non-Parquet scans.

["Tim Armstrong (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-6625?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tim Armstrong reassigned IMPALA-6625:
-------------------------------------

    Assignee: Pooja Nilangekar

> Skip dictionary and collection conjunct assignment for non-Parquet scans.
> -------------------------------------------------------------------------
>
>                 Key: IMPALA-6625
>                 URL: https://issues.apache.org/jira/browse/IMPALA-6625
>             Project: IMPALA
>          Issue Type: Improvement
>          Components: Frontend
>    Affects Versions: Impala 2.9.0, Impala 2.10.0, Impala 2.11.0
>            Reporter: Alexander Behm
>            Assignee: Pooja Nilangekar
>            Priority: Critical
>              Labels: perf, planner
>
> In HdfsScanNode.init() we try to assign dictionary and collection conjuncts even for non-Parquet scans. Such predicates only make sense for Parquet scans, so there is no point in collecting them for other scans.
> The current behavior is undesirable because:
> * init() can be substantially slower because assigning dictionary filters may involve evaluating exprs in the BE which can be expensive
> * the explain plan of non-Parquet scans may have a section "parquet dictionary predicates" which is confusing/misleading
> Relevant code snippet from HdfsScanNode:
> {code}
> @Override
>   public void init(Analyzer analyzer) throws ImpalaException {
>     conjuncts_ = orderConjunctsByCost(conjuncts_);
>     checkForSupportedFileFormats();
>     assignCollectionConjuncts(analyzer);
>     computeDictionaryFilterConjuncts(analyzer);
>     // compute scan range locations with optional sampling
>     Set<HdfsFileFormat> fileFormats = computeScanRangeLocations(analyzer);
> ...
>     if (fileFormats.contains(HdfsFileFormat.PARQUET)) { <--- assignment should go in here
>       computeMinMaxTupleAndConjuncts(analyzer);
>     }
> ...
> }
> {code}



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