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