Expand Json filter plugin for Embulk

expand columns having json into multiple columns

Overview

• Plugin type: filter

Configuration

• json_column_name: a column name having json to be expanded (string, required)
• root: root property to start fetching each entries, specify in JsonPath style (string, default: "$.")
• expanded_columns: columns expanded into multiple columns (array of hash, required)
  • name: name of the column. you can define JsonPath style.
  • type: type of the column (see below)
  • format: format of the timestamp if type is timestamp
  • timezone: Time zone of each timestamp columns if values don’t include time zone description (UTC by default)
• keep_expanding_json_column: Not remove the expanding json column from input schema if it's true (false by default)
• default_timezone: Time zone of timestamp columns if values don’t include time zone description (UTC by default)
• stop_on_invalid_record: Stop bulk load transaction if an invalid record is included (false by default)
• cache_provider: Cache provider name for JsonPath. "LRU" and "NOOP" are built-in. You can specify user defined class. (string, default: "LRU")
  • "NOOP" becomes default in the future.

---

type of the column

name	description
boolean	true or false
long	64-bit signed integers
timestamp	Date and time with nano-seconds precision
double	64-bit floating point numbers
string	Strings

Example

filters:
  - type: expand_json
    json_column_name: json_payload
    root: "$."
    expanded_columns:
      - {name: "phone_numbers", type: string}
      - {name: "app_id", type: long}
      - {name: "point", type: double}
      - {name: "created_at", type: timestamp, format: "%Y-%m-%d", timezone: "UTC"}
      - {name: "profile.anniversary.et", type: string}
      - {name: "profile.anniversary.voluptatem", type: string}
      - {name: "profile.like_words[1]", type: string}
      - {name: "profile.like_words[2]", type: string}
      - {name: "profile.like_words[0]", type: string}

Note

• If the value evaluated by JsonPath is Array or Hash, the value is written as JSON.

Dependencies

• https://github.com/jayway/JsonPath
  • use to evaluate JsonPath
  • Apache License Version 2.0

Development

Run Example

$ ./gradlew gem
$ embulk run -Ibuild/gemContents/lib ./example/config.yml

Build

$ ./gradlew gem  # -t to watch change of files and rebuild continuously

Benchmark for cache_provider option

In some cases, cache_provider: NOOP improves the performance of this plugin by 3 times (embulk#41). So we do a benchmark about cache_provider. In our case, cache_provider: noop improves the performance by 1.5 times.

use expand_json filter	cache_provider	Time took	records/s
false	none	7.62s	1,325,459/s
true	"LRU"	2m9s	78,025/s
true	"NOOP"	1m25s	118,476/s

You can reproduce the bench by the below way.

./gradlew gem
./bench/run.sh

For Maintainers

Release

Modify version in build.gradle at a detached commit, and then tag the commit with an annotation.

git checkout --detach master

(Edit: Remove "-SNAPSHOT" in "version" in build.gradle.)

git add build.gradle

git commit -m "Release vX.Y.Z"

git tag -a vX.Y.Z

(Edit: Write a tag annotation in the changelog format.)

See Keep a Changelog for the changelog format. We adopt a part of it for Git's tag annotation like below.

## [X.Y.Z] - YYYY-MM-DD

### Added
- Added a feature.

### Changed
- Changed something.

### Fixed
- Fixed a bug.

Push the annotated tag, then. It triggers a release operation on GitHub Actions after approval.

git push -u origin vX.Y.Z

Contributor

• @Civitaspo
• @muga
• @sakama