mirror of https://github.com/minio/minio.git
133 lines
6.5 KiB
Markdown
133 lines
6.5 KiB
Markdown
# Select API Quickstart Guide [](https://slack.min.io)
|
||
|
||
Traditional retrieval of objects is always as whole entities, i.e GetObject for a 5 GiB object, will always return 5 GiB of data. S3 Select API allows us to retrieve a subset of data by using simple SQL expressions. By using Select API to retrieve only the data needed by the application, drastic performance improvements can be achieved.
|
||
|
||
You can use the Select API to query objects with following features:
|
||
|
||
- Objects must be in CSV, JSON, or Parquet(*) format.
|
||
- UTF-8 is the only encoding type the Select API supports.
|
||
- GZIP or BZIP2 - CSV and JSON files can be compressed using GZIP, BZIP2, [ZSTD](https://facebook.github.io/zstd/), and streaming formats of [LZ4](https://lz4.github.io/lz4/), [S2](https://github.com/klauspost/compress/tree/master/s2#s2-compression) and [SNAPPY](http://google.github.io/snappy/).
|
||
- Parquet API supports columnar compression for using GZIP, Snappy, LZ4. Whole object compression is not supported for Parquet objects.
|
||
- Server-side encryption - The Select API supports querying objects that are protected with server-side encryption.
|
||
|
||
Type inference and automatic conversion of values is performed based on the context when the value is un-typed (such as when reading CSV data). If present, the CAST function overrides automatic conversion.
|
||
|
||
The [mc sql](https://docs.min.io/docs/minio-client-complete-guide.html#sql) command can be used for executing queries using the command line.
|
||
|
||
(*) Parquet is disabled on the MinIO server by default. See below how to enable it.
|
||
|
||
## Enabling Parquet Format
|
||
|
||
Parquet is DISABLED by default since hostile crafted input can easily crash the server.
|
||
|
||
If you are in a controlled environment where it is safe to assume no hostile content can be uploaded to your cluster you can safely enable Parquet.
|
||
To enable Parquet set the environment variable `MINIO_API_SELECT_PARQUET=on`.
|
||
|
||
## Example using Python API
|
||
|
||
### 1. Prerequisites
|
||
|
||
- Install MinIO Server from [here](https://docs.min.io/docs/minio-quickstart-guide).
|
||
- Familiarity with AWS S3 API.
|
||
- Familiarity with Python and installing dependencies.
|
||
|
||
### 2. Install boto3
|
||
|
||
Install `aws-sdk-python` from AWS SDK for Python official docs [here](https://aws.amazon.com/sdk-for-python/)
|
||
|
||
### 3. Example
|
||
|
||
As an example, let us take a gzip compressed CSV file. Without S3 Select, we would need to download, decompress and process the entire CSV to get the data you needed. With Select API, can use a simple SQL expression to return only the data from the CSV you’re interested in, instead of retrieving the entire object. Following Python example shows how to retrieve the first column `Location` from an object containing data in CSV format.
|
||
|
||
Please replace ``endpoint_url``,``aws_access_key_id``, ``aws_secret_access_key``, ``Bucket`` and ``Key`` with your local setup in this ``select.py`` file.
|
||
|
||
```py
|
||
#!/usr/bin/env/env python3
|
||
import boto3
|
||
|
||
s3 = boto3.client('s3',
|
||
endpoint_url='http://localhost:9000',
|
||
aws_access_key_id='minio',
|
||
aws_secret_access_key='minio123',
|
||
region_name='us-east-1')
|
||
|
||
r = s3.select_object_content(
|
||
Bucket='mycsvbucket',
|
||
Key='sampledata/TotalPopulation.csv.gz',
|
||
ExpressionType='SQL',
|
||
Expression="select * from s3object s where s.Location like '%United States%'",
|
||
InputSerialization={
|
||
'CSV': {
|
||
"FileHeaderInfo": "USE",
|
||
},
|
||
'CompressionType': 'GZIP',
|
||
},
|
||
OutputSerialization={'CSV': {}},
|
||
)
|
||
|
||
for event in r['Payload']:
|
||
if 'Records' in event:
|
||
records = event['Records']['Payload'].decode('utf-8')
|
||
print(records)
|
||
elif 'Stats' in event:
|
||
statsDetails = event['Stats']['Details']
|
||
print("Stats details bytesScanned: ")
|
||
print(statsDetails['BytesScanned'])
|
||
print("Stats details bytesProcessed: ")
|
||
print(statsDetails['BytesProcessed'])
|
||
```
|
||
|
||
## 4. Run the Program
|
||
|
||
Upload a sample dataset to MinIO using the following commands.
|
||
|
||
```sh
|
||
curl "https://population.un.org/wpp/Download/Files/1_Indicators%20(Standard)/CSV_FILES/WPP2019_TotalPopulationBySex.csv" > TotalPopulation.csv
|
||
mc mb myminio/mycsvbucket
|
||
gzip TotalPopulation.csv
|
||
mc cp TotalPopulation.csv.gz myminio/mycsvbucket/sampledata/
|
||
```
|
||
|
||
Now let us proceed to run our select example to query for `Location` which matches `United States`.
|
||
|
||
```sh
|
||
$ python3 select.py
|
||
840,United States of America,2,Medium,1950,1950.5,79233.218,79571.179,158804.395
|
||
|
||
840,United States of America,2,Medium,1951,1951.5,80178.933,80726.116,160905.035
|
||
|
||
840,United States of America,2,Medium,1952,1952.5,81305.206,82019.632,163324.851
|
||
|
||
840,United States of America,2,Medium,1953,1953.5,82565.875,83422.307,165988.190
|
||
....
|
||
....
|
||
....
|
||
|
||
Stats details bytesScanned:
|
||
6758866
|
||
Stats details bytesProcessed:
|
||
25786743
|
||
```
|
||
|
||
For a more detailed SELECT SQL reference, please see [here](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-select.html)
|
||
|
||
## 5. Explore Further
|
||
|
||
- [Use `mc` with MinIO Server](https://docs.min.io/docs/minio-client-quickstart-guide)
|
||
- [Use `mc sql` with MinIO Server](https://docs.min.io/docs/minio-client-complete-guide.html#sql)
|
||
- [Use `minio-go` SDK with MinIO Server](https://docs.min.io/docs/golang-client-quickstart-guide)
|
||
- [Use `aws-cli` with MinIO Server](https://docs.min.io/docs/aws-cli-with-minio)
|
||
- [Use `s3cmd` with MinIO Server](https://docs.min.io/docs/s3cmd-with-minio)
|
||
- [The MinIO documentation website](https://docs.min.io)
|
||
|
||
## 6. Implementation Status
|
||
|
||
- Full AWS S3 [SELECT SQL](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-select.html) syntax is supported.
|
||
- All [operators](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-operators.html) are supported.
|
||
- All aggregation, conditional, type-conversion and string functions are supported.
|
||
- JSON path expressions such as `FROM S3Object[*].path` are not yet evaluated.
|
||
- Large numbers (outside of the signed 64-bit range) are not yet supported.
|
||
- The Date [functions](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-date.html) `DATE_ADD`, `DATE_DIFF`, `EXTRACT` and `UTCNOW` along with type conversion using `CAST` to the `TIMESTAMP` data type are currently supported.
|
||
- AWS S3's [reserved keywords](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-keyword-list.html) list is not yet respected.
|
||
- CSV input fields (even quoted) cannot contain newlines even if `RecordDelimiter` is something else.
|