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<!---
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing,
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied. See the License for the
specific language governing permissions and limitations
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-->
# parquet\_reader
A tool to read Parquet files and write selected columns into TEXT, JSON, or CSV files.
## Usage
```
$ ./parquet_reader -h
Parquet Reader (version 0.1.20220629.1846)
Usage:
parquet_reader -h | --help
parquet_reader [--only-metadata] [--no-metadata] [--no-memory-map] [--json] [--csv] [--output=FILE]
[--print-key-value-metadata] [--int96-timestamp] [--columns=COLUMNS] <file>
Options:
-h --help Show this screen.
--print-key-value-metadata Print out the key-value metadata. [default: false]
--only-metadata Stop after printing metadata, no values.
--no-metadata Do not print metadata.
--output=FILE Specify output file for data. [default: -]
--no-memory-map Disable memory mapping the file.
--int96-timestamp Parse INT96 as TIMESTAMP for legacy support.
--json Format output as JSON instead of text.
--csv Format output as CSV instead of text.
--columns=COLUMNS Specify a subset of columns to print, comma delimited indexes.
```
# Examples
## Text
```
$ ./parquet_reader --no-metadata v0.7.1.parquet
carat |cut |color |clarity |depth |table |price |x |y |z |__index_level_0__ |
0.230000 |Ideal |E |SI2 |61.500000 |55.000000 |326 |3.950000 |3.980000 |2.430000 |0 |
0.210000 |Premium |E |SI1 |59.800000 |61.000000 |326 |3.890000 |3.840000 |2.310000 |1 |
0.230000 |Good |E |VS1 |56.900000 |65.000000 |327 |4.050000 |4.070000 |2.310000 |2 |
0.290000 |Premium |I |VS2 |62.400000 |58.000000 |334 |4.200000 |4.230000 |2.630000 |3 |
0.310000 |Good |J |SI2 |63.300000 |58.000000 |335 |4.340000 |4.350000 |2.750000 |4 |
0.240000 |Very Good |J |VVS2 |62.800000 |57.000000 |336 |3.940000 |3.960000 |2.480000 |5 |
0.240000 |Very Good |I |VVS1 |62.300000 |57.000000 |336 |3.950000 |3.980000 |2.470000 |6 |
0.260000 |Very Good |H |SI1 |61.900000 |55.000000 |337 |4.070000 |4.110000 |2.530000 |7 |
0.220000 |Fair |E |VS2 |65.100000 |61.000000 |337 |3.870000 |3.780000 |2.490000 |8 |
0.230000 |Very Good |H |VS1 |59.400000 |61.000000 |338 |4.000000 |4.050000 |2.390000 |9 |
```
## JSON
```
$ ./parquet_reader --no-metadata --json v0.7.1.parquet
[{"carat":0.23,"cut":"Ideal","color":"E","clarity":"SI2","depth":61.5,"table":55,"price":326,"x":3.95,"y":3.98,"z":2.43,"__index_level_0__":0},{"carat":0.21,"cut":"Premium","color":"E","clarity":"SI1","depth":59.8,"table":61,"price":326,"x":3.89,"y":3.84,"z":2.31,"__index_level_0__":1},{"carat":0.23,"cut":"Good","color":"E","clarity":"VS1","depth":56.9,"table":65,"price":327,"x":4.05,"y":4.07,"z":2.31,"__index_level_0__":2},{"carat":0.29,"cut":"Premium","color":"I","clarity":"VS2","depth":62.4,"table":58,"price":334,"x":4.2,"y":4.23,"z":2.63,"__index_level_0__":3},{"carat":0.31,"cut":"Good","color":"J","clarity":"SI2","depth":63.3,"table":58,"price":335,"x":4.34,"y":4.35,"z":2.75,"__index_level_0__":4},{"carat":0.24,"cut":"Very Good","color":"J","clarity":"VVS2","depth":62.8,"table":57,"price":336,"x":3.94,"y":3.96,"z":2.48,"__index_level_0__":5},{"carat":0.24,"cut":"Very Good","color":"I","clarity":"VVS1","depth":62.3,"table":57,"price":336,"x":3.95,"y":3.98,"z":2.47,"__index_level_0__":6},{"carat":0.26,"cut":"Very Good","color":"H","clarity":"SI1","depth":61.9,"table":55,"price":337,"x":4.07,"y":4.11,"z":2.53,"__index_level_0__":7},{"carat":0.22,"cut":"Fair","color":"E","clarity":"VS2","depth":65.1,"table":61,"price":337,"x":3.87,"y":3.78,"z":2.49,"__index_level_0__":8},{"carat":0.23,"cut":"Very Good","color":"H","clarity":"VS1","depth":59.4,"table":61,"price":338,"x":4,"y":4.05,"z":2.39,"__index_level_0__":9}]
```
## CSV
```
$ ./parquet_reader --no-metadata --csv v0.7.1.parquet
"carat","cut","color","clarity","depth","table","price","x","y","z","__index_level_0__"
0.23,"Ideal","E","SI2",61.5,55,326,3.95,3.98,2.43,0
0.21,"Premium","E","SI1",59.8,61,326,3.89,3.84,2.31,1
0.23,"Good","E","VS1",56.9,65,327,4.05,4.07,2.31,2
0.29,"Premium","I","VS2",62.4,58,334,4.2,4.23,2.63,3
0.31,"Good","J","SI2",63.3,58,335,4.34,4.35,2.75,4
0.24,"Very Good","J","VVS2",62.8,57,336,3.94,3.96,2.48,5
0.24,"Very Good","I","VVS1",62.3,57,336,3.95,3.98,2.47,6
0.26,"Very Good","H","SI1",61.9,55,337,4.07,4.11,2.53,7
0.22,"Fair","E","VS2",65.1,61,337,3.87,3.78,2.49,8
0.23,"Very Good","H","VS1",59.4,61,338,4,4.05,2.39,9
```
## Write JSON to output file
```
$ ./parquet_reader --no-metadata --json --output=data.json v0.7.1.parquet
$ jq . data.json
[
{
"carat": 0.23,
"cut": "Ideal",
"color": "E",
"clarity": "SI2",
"depth": 61.5,
"table": 55,
"price": 326,
"x": 3.95,
...
```
## Write CSV to output file
```
$ ./parquet_reader --no-metadata --csv --output=data.csv v0.7.1.parquet
```
|
