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Commit 02149ff0 authored by Cheng Lian's avatar Cheng Lian
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[SPARK-8848] [SQL] Refactors Parquet write path to follow parquet-format

This PR refactors Parquet write path to follow parquet-format spec.  It's a successor of PR #7679, but with less non-essential changes.

Major changes include:

1.  Replaces `RowWriteSupport` and `MutableRowWriteSupport` with `CatalystWriteSupport`

    - Writes Parquet data using standard layout defined in parquet-format

      Specifically, we are now writing ...

      - ... arrays and maps in standard 3-level structure with proper annotations and field names
      - ... decimals as `INT32` and `INT64` whenever possible, and taking `FIXED_LEN_BYTE_ARRAY` as the final fallback

    - Supports legacy mode which is compatible with Spark 1.4 and prior versions

      The legacy mode is by default off, and can be turned on by flipping SQL option `spark.sql.parquet.writeLegacyFormat` to `true`.

    - Eliminates per value data type dispatching costs via prebuilt composed writer functions

1.  Cleans up the last pieces of old Parquet support code

As pointed out by rxin previously, we probably want to rename all those `Catalyst*` Parquet classes to `Parquet*` for clarity.  But I'd like to do this in a follow-up PR to minimize code review noises in this one.

Author: Cheng Lian <lian@databricks.com>

Closes #8988 from liancheng/spark-8848/standard-parquet-write-path.
parent 2816c89b
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