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From "Lars Volker (JIRA)" <>
Subject [jira] [Resolved] (IMPALA-4819) Populate min/max statistics in Parquet files for Timestamp values
Date Thu, 11 May 2017 10:59:04 GMT


Lars Volker resolved IMPALA-4819.
       Resolution: Fixed
    Fix Version/s: Impala 2.9.0

IMPALA-4815, IMPALA-4817, IMPALA-4819: Write and Read Parquet Statistics for remaining types

This change adds functionality to write and read parquet::Statistics for
Decimal, String, and Timestamp values. As an exception, we don't read
statistics for CHAR columns, since CHAR support is broken in Impala

This change also switches from using the deprecated fields 'min' and
'max' to populate the new fields 'min_value' and 'max_value' in
parquet::Statistics, that were added in parquet-format pull request #46.

The HdfsParquetScanner will preferably read the new fields if they are
populated and if the column order 'TypeDefinedOrder' has been used to
compute the statistics. For columns without a column order set or with
only the deprecated fields populated, the scanner will read them only if
they are of simple numeric type, i.e. boolean, integer, or floating

This change removes the validation of the Parquet Statistics we write to
Hive from the tests, since Hive does not write the new fields. Instead
it adds a parquet file written by Hive that uses the deprecated fields
for its statistics. It uses that file to exercise the fallback logic for
supported types in a test.

This change also cleans up the interface of ParquetPlainEncoder in

Change-Id: I3ef4a5d25a57c82577fd498d6d1c4297ecf39312
Reviewed-by: Lars Volker <>
Tested-by: Lars Volker <>

> Populate min/max statistics in Parquet files for Timestamp values
> -----------------------------------------------------------------
>                 Key: IMPALA-4819
>                 URL:
>             Project: IMPALA
>          Issue Type: New Feature
>          Components: Backend
>    Affects Versions: Impala 2.9.0
>            Reporter: Lars Volker
>            Assignee: Lars Volker
>              Labels: parquet
>             Fix For: Impala 2.9.0
> Due to several issues in parquet-mr and subsequently Hive, IMPALA-3909 only adds write
support for min/max statistics for numeric types. We should also add write support for Timestamp
values. This is currently blocked by [PARQUET-840|]
and is related to [PARQUET-839|].

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