Update more docs and also the developer.md doc (#414)

* update dev.md

* update docs

DEVELOPERS.md

@@ -93,3 +93,20 @@ can be displayed. For example, the following command creates a
 ```bash
 dot -Tpdf < /tmp/plan.dot > /tmp/plan.pdf
 ```
+
+## How to format `.md` document
+
+We are using `prettier` to format `.md` files.
+
+You can either use `npm i -g prettier` to install it globally or use `npx` to run it as a standalone binary. Using `npx` required a working node environment. Upgrading to the latest prettier is recommended (by adding `--upgrade` to the `npm` command).
+
+```bash
+$ prettier --version
+2.3.0
+```
+
+After you've confirmed your prettier version, you can format all the `.md` files:
+
+```bash
+prettier -w {ballista,datafusion,datafusion-examples,dev,docs,python}/**/*.md
+```

datafusion-examples/examples/README.md

@@ -25,4 +25,4 @@ The examples `csv_sql.rs` and `parquet_sql.rs` demonstrate building a query plan
 
 ## Distributed
 
-The `flight-client.rs` and `flight-server.rs` examples demonstrate how to run DataFusion as a standalone process and execute SQL queries from a client using the Flight protocol.
+The `flight-client.rs` and `flight-server.rs` examples demonstrate how to run DataFusion as a standalone process and execute SQL queries from a client using the Flight protocol.

dev/README.md

@@ -33,14 +33,16 @@ committer.
 
 ## How to merge a Pull request
 
-Please don't merge PRs using the Github Web interface.  Instead, set up
-your git clone such as to have a remote named ``apache`` pointing to the
+Please don't merge PRs using the Github Web interface. Instead, set up
+your git clone such as to have a remote named `apache` pointing to the
 official Arrow repository:
+
 ```
 git remote add apache git@github.com:apache/arrow.git
 ```
 
 and then run the following command:
+
 ```
 ./dev/merge_arrow_pr.sh
 ```
@@ -64,10 +66,13 @@ If these aren't supplied, the script will ask you the values of them.
 Note that the directory name of your Arrow git clone must be called `arrow`.
 
 example output:
+
 ```
 Which pull request would you like to merge? (e.g. 34):
 ```
+
 Type the pull request number (from https://github.com/apache/arrow/pulls) and hit enter.
+
 ```
 === Pull Request #X ===
 title	Blah Blah Blah
@@ -77,16 +82,20 @@ url	https://api.github.com/repos/apache/arrow/pulls/X
 
 Proceed with merging pull request #3? (y/n):
 ```
+
 If this looks good, type y and hit enter.
+
 ```
 From git-wip-us.apache.org:/repos/asf/arrow.git
  * [new branch]      master     -> PR_TOOL_MERGE_PR_3_MASTER
 Switched to branch 'PR_TOOL_MERGE_PR_3_MASTER'
 
 Merge complete (local ref PR_TOOL_MERGE_PR_3_MASTER). Push to apache? (y/n):
 ```
+
 A local branch with the merge has been created.
 type y and hit enter to push it to apache master
+
 ```
 Counting objects: 67, done.
 Delta compression using up to 4 threads.
@@ -115,6 +124,7 @@ Merge hash: 485658a5
 
 Would you like to pick 485658a5 into another branch? (y/n):
 ```
+
 For now just say n as we have 1 branch
 
 ## Verifying Release Candidates

dev/archery/archery/crossbow/tests/fixtures/crossbow-success-message.md

@@ -2,9 +2,9 @@ Revision: {revision}
 
 Submitted crossbow builds: [{repo} @ {branch}](https://github.com/{repo}/branches/all?query={branch})
 
-|Task|Status|
-|----|------|
-|docker-cpp-cmake32|[![CircleCI](https://img.shields.io/circleci/build/github/{repo}/{branch}-circle-docker-cpp-cmake32.svg)](https://circleci.com/gh/{repo}/tree/{branch}-circle-docker-cpp-cmake32)|
-|wheel-osx-cp36m|[![TravisCI](https://img.shields.io/travis/{repo}/{branch}-travis-wheel-osx-cp36m.svg)](https://travis-ci.com/{repo}/branches)|
-|wheel-osx-cp37m|[![TravisCI](https://img.shields.io/travis/{repo}/{branch}-travis-wheel-osx-cp37m.svg)](https://travis-ci.com/{repo}/branches)|
-|wheel-win-cp36m|[![Appveyor](https://img.shields.io/appveyor/ci/{repo}/{branch}-appveyor-wheel-win-cp36m.svg)](https://ci.appveyor.com/project/{repo}/history)|
+| Task               | Status                                                                                                                                                                            |
+| ------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| docker-cpp-cmake32 | [![CircleCI](https://img.shields.io/circleci/build/github/{repo}/{branch}-circle-docker-cpp-cmake32.svg)](https://circleci.com/gh/{repo}/tree/{branch}-circle-docker-cpp-cmake32) |
+| wheel-osx-cp36m    | [![TravisCI](https://img.shields.io/travis/{repo}/{branch}-travis-wheel-osx-cp36m.svg)](https://travis-ci.com/{repo}/branches)                                                    |
+| wheel-osx-cp37m    | [![TravisCI](https://img.shields.io/travis/{repo}/{branch}-travis-wheel-osx-cp37m.svg)](https://travis-ci.com/{repo}/branches)                                                    |
+| wheel-win-cp36m    | [![Appveyor](https://img.shields.io/appveyor/ci/{repo}/{branch}-appveyor-wheel-win-cp36m.svg)](https://ci.appveyor.com/project/{repo}/history)                                    |

dev/benchmarking/README.md

@@ -17,7 +17,6 @@
   ~ under the License.
   -->
 
-
 > NOTE: For those deploying this database, Postgres does not by default use
 > UTF-8, however it is [required for the jsonb][pg-jsonb] format used in
 > some columns to always work. This [stackoverflow post][so-utf8] describes
@@ -81,7 +80,6 @@ database will be set up automatically once the container is running.
 To start the containers, be sure to have [Docker installed][docker],
 and then run the following from this directory (arrow/dev/benchmarking).
 
-
 ```
 docker-compose up
 ```
@@ -111,9 +109,11 @@ The `psql` shell client is bundled with the PostgreSQL core distribution
 available from the [Postgres download page][postgres-downloads].
 Using the `PG_USER` defined in the `.env` file (currently "benchmark"),
 the command to connect to the container is:
+
 ```shell
 psql -h localhost -p 5432 -U benchmark
 ```
+
 There is an example script in [examples/example.sql](examples/example.sql) that
 runs some queries against the database. To run it in the psql client, type
 the following in the psql command-line interface:
@@ -168,14 +168,15 @@ The script [graphql_submit.sh](./graphql_submit.sh) simplifies submission
 to the database via curl. Examples:
 
 ```shell
-./graphql_submit.sh benchmarks examples/benchmark_example.json 
+./graphql_submit.sh benchmarks examples/benchmark_example.json
 ./graphql_submit.sh runs examples/benchmark_run_example.json
 ```
 
 #### Querying
 
 The output of the query is a JSON object that is hard to read on the command line.
 Here is an example query in the shell:
+
 ```shell
 curl -X POST \
   -H "Content-Type: application/json"  \
@@ -190,6 +191,7 @@ which (if you have previously run the "examples.sql" command) yields
 ```
 
 Here is an example query using Python:
+
 ```python
 import json
 import requests
@@ -219,7 +221,6 @@ for row in response.json()['data']['allEnvironmentViews']['edges']:
 > how to do it for Amazon RDS. This [section of the docs][pg-charset]
 > states how to do it in general, i.e.: `initdb -E UTF8`.
 
-
 ## Quick reference
 
 - String variables `'have single quotes'`

dev/release/VERIFY.md

@@ -34,11 +34,11 @@ GLib, Java and JavaScript builds on Linux and macOS. Read the comments in
 
 You need the followings to verify C GLib build:
 
-  * GLib
-  * GObject Introspection
-  * Ruby (not EOL-ed version is required)
-  * gobject-introspection gem
-  * test-unit gem
+- GLib
+- GObject Introspection
+- Ruby (not EOL-ed version is required)
+- gobject-introspection gem
+- test-unit gem
 
 You can install them by the followings on Debian GNU/Linux and Ubuntu:
 

dev/tasks/conda-recipes/README.md

@@ -54,14 +54,12 @@ related parts (the cloning of arrow and the jinja templated variables) and
 moving the matrix definitions like [this][matrix-definition] to the crossbow
 [tasks.yml][../tasks.yml] config file.
 
-
 ### Porting recipes from crossbow to the upstream feedstocks
 
 Theoretically these recipes should be up to date with the actual version of
 Arrow, so during the release procedure the content of these recipes should be
 copied to the upstream feedstocks.
 
-
 [arrow-cpp-feedstock]: https://github.com/conda-forge/arrow-cpp-feedstock
 [parquet-cpp-feedstock]: https://github.com/conda-forge/parquet-cpp-feedstock
 [matrix-definition]: https://github.com/conda-forge/arrow-cpp-feedstock/blob/master/.azure-pipelines/azure-pipelines-linux.yml#L12

dev/tasks/gandiva-jars/README.md

@@ -26,4 +26,4 @@ Do the following to update arrow manylinux docker image for building Gandiva Jar
 - Export JAVA_HOME environment variable.
 - Then update build_boost.sh under python/manylinux1/scripts to build boost statically.
 
-Please look at https://github.com/praveenbingo/arrow/tree/buildGandivaDocker that already has these changes.
+Please look at https://github.com/praveenbingo/arrow/tree/buildGandivaDocker that already has these changes.

dev/tasks/linux-packages/README.md

@@ -21,9 +21,9 @@
 
 ## Requirements
 
-  * Ruby
-  * Docker
-  * Tools to build tar.gz for Apache Arrow C++ and GLib
+- Ruby
+- Docker
+- Tools to build tar.gz for Apache Arrow C++ and GLib
 
 ## How to build .deb packages