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ASF GitHub Bot commented on DRILL-2743: --------------------------------------- GitHub user StevenMPhillips opened a pull request: https://github.com/apache/drill/pull/114 DRILL-2743: Parquet file metadata caching You can merge this pull request into a Git repository by running: $ git pull https://github.com/StevenMPhillips/incubator-drill meta2 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/drill/pull/114.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #114 ---- commit 371153d7dfb4cd0ad5b0042f6ca2df255e81c52f Author: Steven Phillips <sphill...@maprtech.com> Date: 2015-03-13T23:12:34Z DRILL-2743: Parquet file metadata caching ---- > Parquet file metadata caching > ----------------------------- > > Key: DRILL-2743 > URL: https://issues.apache.org/jira/browse/DRILL-2743 > Project: Apache Drill > Issue Type: New Feature > Components: Storage - Parquet > Reporter: Steven Phillips > Assignee: Steven Phillips > Fix For: 1.3.0 > > Attachments: DRILL-2743.patch, drill.parquet_metadata > > > To run a query against parquet files, we have to first recursively search the > directory tree for all of the files, get the block locations for each file, > and read the footer from each file, and this is done during the planning > phase. When there are many files, this can result in a very large delay in > running the query, and it does not scale. > However, there isn't really any need to read the footers during planning, if > we instead treat each parquet file as a single work unit, all we need to know > are the block locations for the file, the number of rows, and the columns. We > should store only the information which we need for planning in a file > located in the top directory for a given parquet table, and then we can delay > reading of the footers until execution time, which can be done in parallel. -- This message was sent by Atlassian JIRA (v6.3.4#6332)