update readme with json schema command

README.md

@@ -14,19 +14,11 @@ You can download release binaries [here](https://github.com/manojkarthick/pqrs/r
 
 ### Alternative methods
 
-#### Using macports
-
-You can use [macports](https://www.macports.org/) to install `pqrs` if you are a macOS user.
-
-```
-sudo port install pqrs
-```
-
 #### Using Homebrew
 
 For macOS users, `pqrs` is available as a homebrew tap.
 
-```
+```shell
 brew tap manojkarthick/pqrs
 brew install pqrs
 ```
@@ -35,15 +27,15 @@ brew install pqrs
 
 `pqrs` is also available for installation from [crates.io](https://crates.io/crates/pqrs) using `cargo`, the rust package manager.
 
-```shell script
+```shell
 cargo install pqrs
 ```
 
 #### Building and running from source
 
 Make sure you have `rustc` and `cargo` installed on your machine.
 
-```
+```shell
 git clone https://github.com/manojkarthick/pqrs.git
 cargo build --release
 ./target/release/pqrs
@@ -53,9 +45,9 @@ cargo build --release
 
 The below snippet shows the available subcommands:
 
-```
+```shell
 ❯ pqrs --help
-pqrs 0.2.0
+pqrs 0.2.1
 Manoj Karthick
 Apache Parquet command-line utility
 
@@ -83,21 +75,21 @@ SUBCOMMANDS:
 Prints the contents of the given files and folders. Recursively traverses and prints all the files if the input is a directory. 
 Supports json-like, json or CSV format. Use `--json` for JSON output and `--csv` for CSV output.
 
-```
+```shell
 ❯ pqrs cat data/cities.parquet
 {continent: "Europe", country: {name: "France", city: ["Paris", "Nice", "Marseilles", "Cannes"]}}
 {continent: "Europe", country: {name: "Greece", city: ["Athens", "Piraeus", "Hania", "Heraklion", "Rethymnon", "Fira"]}}
 {continent: "North America", country: {name: "Canada", city: ["Toronto", "Vancouver", "St. John's", "Saint John", "Montreal", "Halifax", "Winnipeg", "Calgary", "Saskatoon", "Ottawa", "Yellowknife"]}}
 ```
 
-```
+```shell
 ❯ pqrs cat data/cities.parquet --json
 {"continent":"Europe","country":{"name":"France","city":["Paris","Nice","Marseilles","Cannes"]}}
 {"continent":"Europe","country":{"name":"Greece","city":["Athens","Piraeus","Hania","Heraklion","Rethymnon","Fira"]}}
 {"continent":"North America","country":{"name":"Canada","city":["Toronto","Vancouver","St. John's","Saint John","Montreal","Halifax","Winnipeg","Calgary","Saskatoon","Ottawa","Yellowknife"]}}
 ```
 
-```
+```shell
 ❯ pqrs cat data/simple.parquet --csv
 foo,bar
 1,2
@@ -110,7 +102,7 @@ NOTE: CSV format is not supported for files that contain Struct or Byte fields.
 
 Prints the first N records of the parquet file. Use `--records` flag to set the number of records.
 
-```
+```shell
 ❯ pqrs head data/cities.parquet --json --records 2
 {"continent":"Europe","country":{"name":"France","city":["Paris","Nice","Marseilles","Cannes"]}}
 {"continent":"Europe","country":{"name":"Greece","city":["Athens","Piraeus","Hania","Heraklion","Rethymnon","Fira"]}}
@@ -122,7 +114,7 @@ Merge two Parquet files by placing row groups (or blocks) from the two files one
 
 Disclaimer: This does not combine the files to have optimized row groups, do not use it in production!
 
-```
+```shell
 ❯ pqrs merge --input data/pems-1.snappy.parquet data/pems-2.snappy.parquet --output data/pems-merged.snappy.parquet
 
 ❯ ls -al data
@@ -139,8 +131,8 @@ drwxr-xr-x  20 manojkarthick  staff     640 Feb 14 08:52 ..
 
 Print the number of rows present in the parquet file.
 
-```
-❯ pqrs rowcount data/pems-1.snappy.parquet data/pems-2.snappy.parquet
+```shell
+❯ pqrs row-count data/pems-1.snappy.parquet data/pems-2.snappy.parquet
 File Name: data/pems-1.snappy.parquet: 2693 rows
 File Name: data/pems-2.snappy.parquet: 2880 rows
 ```
@@ -149,7 +141,7 @@ File Name: data/pems-2.snappy.parquet: 2880 rows
 
 Prints a random sample of records from the given parquet file.
 
-```
+```shell
 ❯ pqrs sample data/pems-1.snappy.parquet --records 3
 {timeperiod: "01/17/2016 07:01:27", flow1: 0, occupancy1: 0E0, speed1: 0E0, flow2: 0, occupancy2: 0E0, speed2: 0E0, flow3: 0, occupancy3: 0E0, speed3: 0E0, flow4: null, occupancy4: null, speed4: null, flow5: null, occupancy5: null, speed5: null, flow6: null, occupancy6: null, speed6: null, flow7: null, occupancy7: null, speed7: null, flow8: null, occupancy8: null, speed8: null}
 {timeperiod: "01/17/2016 07:47:27", flow1: 0, occupancy1: 0E0, speed1: 0E0, flow2: 0, occupancy2: 0E0, speed2: 0E0, flow3: 0, occupancy3: 0E0, speed3: 0E0, flow4: null, occupancy4: null, speed4: null, flow5: null, occupancy5: null, speed5: null, flow6: null, occupancy6: null, speed6: null, flow7: null, occupancy7: null, speed7: null, flow8: null, occupancy8: null, speed8: null}
@@ -160,7 +152,7 @@ Prints a random sample of records from the given parquet file.
 
 Print the schema from the given parquet file. Use the `--detailed` flag to get more detailed stats.
 
-```
+```shell
 ❯ pqrs schema data/cities.parquet
 Metadata for file: data/cities.parquet
 
@@ -180,7 +172,7 @@ message hive_schema {
 }
 ```
 
-```
+```shell
 ❯ pqrs schema data/cities.parquet --detailed
 
 num of row groups: 1
@@ -213,19 +205,25 @@ statistics: {min: [69, 117, 114, 111, 112, 101], max: [78, 111, 114, 116, 104, 3
 
 ```
 
+```shell
+❯ pqrs schema --json data/cities.parquet                                                              
+{"version":1,"num_rows":3,"created_by":"parquet-mr version 1.5.0-cdh5.7.0 (build ${buildNumber})","metadata":null,"columns":[{"optional":"true","physical_type":"BYTE_ARRAY","name":"continent","path":"continent","converted_type":"UTF8"},{"name":"name","converted_type":"UTF8","path":"country.name","physical_type":"BYTE_ARRAY","optional":"true"},{"optional":"true","name":"array_element","physical_type":"BYTE_ARRAY","path":"country.city.bag.array_element","converted_type":"UTF8"}],"message":"message hive_schema {\n  OPTIONAL BYTE_ARRAY continent (UTF8);\n  OPTIONAL group country {\n    OPTIONAL BYTE_ARRAY name (UTF8);\n    OPTIONAL group city (LIST) {\n      REPEATED group bag {\n        OPTIONAL BYTE_ARRAY array_element (UTF8);\n      }\n    }\n  }\n}\n"}
+
+```
+
 ### Subcommand: size
 
 Print the compressed/uncompressed size of the parquet file. Shows uncompressed size by default
 
-```
+```shell
 ❯ pqrs size data/pems-1.snappy.parquet --pretty
 Size in Bytes:
 
 File Name: data/pems-1.snappy.parquet
 Uncompressed Size: 61 KiB
 ```
 
-```
+```shell
 ❯ pqrs size data/pems-1.snappy.parquet --pretty --compressed
 Size in Bytes: