Add select docs and fix return values for Select API (#6300)
This commit is contained in:
Harshavardhana
kannappanr
parent
3de5a3157f
commit
5a4a57700b
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@ -161,19 +161,22 @@ func (api objectAPIHandlers) SelectObjectContentHandler(w http.ResponseWriter, r
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writeErrorResponse(w, ErrInvalidExpressionType, r.URL)
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return
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}
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if len(selectReq.Expression) >= (256 * 1000) {
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if len(selectReq.Expression) >= s3select.MaxExpressionLength {
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writeErrorResponse(w, ErrExpressionTooLong, r.URL)
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return
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}
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if selectReq.InputSerialization.CSV.FileHeaderInfo != CSVFileHeaderInfoUse &&
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selectReq.InputSerialization.CSV.FileHeaderInfo != CSVFileHeaderInfoNone &&
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selectReq.InputSerialization.CSV.FileHeaderInfo != CSVFileHeaderInfoIgnore &&
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selectReq.InputSerialization.CSV.FileHeaderInfo != "" {
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writeErrorResponse(w, ErrInvalidFileHeaderInfo, r.URL)
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return
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}
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if selectReq.OutputSerialization.CSV.QuoteFields != CSVQuoteFieldsAlways &&
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selectReq.OutputSerialization.CSV.QuoteFields != CSVQuoteFieldsAsNeeded &&
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selectReq.OutputSerialization.CSV.QuoteFields != "" {
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writeErrorResponse(w, ErrInvalidQuoteFields, r.URL)
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return
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}
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getObject := objectAPI.GetObject
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@ -205,8 +208,7 @@ func (api objectAPIHandlers) SelectObjectContentHandler(w http.ResponseWriter, r
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}
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go func() {
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defer reader.Close()
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if gerr := getObject(ctx, bucket, object, 0, objInfo.Size, writer,
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objInfo.ETag); gerr != nil {
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if gerr := getObject(ctx, bucket, object, 0, objInfo.Size, writer, objInfo.ETag); gerr != nil {
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pipewriter.CloseWithError(gerr)
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return
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}
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@ -243,10 +245,9 @@ func (api objectAPIHandlers) SelectObjectContentHandler(w http.ResponseWriter, r
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writeErrorResponse(w, toAPIErrorCode(err), r.URL)
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return
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}
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if err := s3s.Execute(w); err != nil {
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if err = s3s.Execute(w); err != nil {
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logger.LogIf(ctx, err)
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}
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return
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}
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}
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89
docs/select/README.md
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89
docs/select/README.md
Normal file
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@ -0,0 +1,89 @@
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# Select API Quickstart Guide [](https://slack.minio.io)
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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.
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> This implementation is compatible with AWS S3 Select API
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## 1. Prerequisites
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- Install Minio Server from [here](http://docs.minio.io/docs/minio-quickstart-guide).
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- Familiarity with AWS S3 API
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- Familiarity with Python and installing dependencies.
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## 2. Install boto3
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Install `aws-sdk-python` from AWS SDK for Python official docs [here](https://aws.amazon.com/sdk-for-python/)
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## 3. Example
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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.
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Please replace ``endpoint_url``,``aws_access_key_id``, ``aws_secret_access_key``, ``Bucket`` and ``Key`` with your local setup in this ``select.py`` file.
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```py
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#!/usr/bin/env/env python3
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import boto3
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s3 = boto3.client('s3',
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endpoint_url='http://localhost:9000',
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aws_access_key_id='minio',
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aws_secret_access_key='minio123',
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region_name='us-east-1')
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r = s3.select_object_content(
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Bucket='mycsvbucket',
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Key='sampledata/TotalPopulation.csv.gz',
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ExpressionType='SQL',
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Expression="select * from s3object s where s.Location like '%United States%'",
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InputSerialization={
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'CSV': {
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"FileHeaderInfo": "USE",
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},
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'CompressionType': 'GZIP',
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},
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OutputSerialization={'CSV': {}},
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)
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for event in r['Payload']:
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if 'Records' in event:
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records = event['Records']['Payload'].decode('utf-8')
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print(records)
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elif 'Stats' in event:
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statsDetails = event['Stats']['Details']
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print("Stats details bytesScanned: ")
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print(statsDetails['BytesScanned'])
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print("Stats details bytesProcessed: ")
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print(statsDetails['BytesProcessed'])
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```
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## 4. Run the Program
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Upload first a sample dataset downloaded from [TotalPopulation.csv](https://esa.un.org/unpd/wpp/DVD/Files/1_Indicators%20(Standard)/CSV_FILES/WPP2017_TotalPopulationBySex.csv) using the following commands.
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```sh
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$ curl "https://esa.un.org/unpd/wpp/DVD/Files/1_Indicators%20(Standard)/CSV_FILES/WPP2017_TotalPopulationBySex.csv" > TotalPopulation.csv
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$ mc mb myminio/mycsvbucket
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$ gzip TotalPopulation.csv
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$ mc cp TotalPopulation.csv.gz myminio/mycsvbucket/sampledata/
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```
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Now let us proceed to run our select example to query for `Location` which matches `United States`.
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```sh
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$ python3 select.py
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840,United States of America,2,Medium,1950,1950.5,79233.218,79571.179,158804.395
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840,United States of America,2,Medium,1951,1951.5,80178.933,80726.116,160905.035
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840,United States of America,2,Medium,1952,1952.5,81305.206,82019.632,163324.851
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840,United States of America,2,Medium,1953,1953.5,82565.875,83422.307,165988.190
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....
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....
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....
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Stats details bytesScanned:
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6758866
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Stats details bytesProcessed:
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25786743
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```
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## 5. Explore Further
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- [Use `mc` with Minio Server](https://docs.minio.io/docs/minio-client-quickstart-guide)
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- [Use `minio-go` SDK with Minio Server](https://docs.minio.io/docs/golang-client-quickstart-guide)
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- [Use `aws-cli` with Minio Server](https://docs.minio.io/docs/aws-cli-with-minio)
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- [Use `s3cmd` with Minio Server](https://docs.minio.io/docs/s3cmd-with-minio)
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- [The Minio documentation website](https://docs.minio.io)
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33
docs/select/select.py
Normal file
33
docs/select/select.py
Normal file
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@ -0,0 +1,33 @@
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#!/usr/bin/env/env python3
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import boto3
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s3 = boto3.client('s3',
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endpoint_url='http://localhost:9000',
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aws_access_key_id='minio',
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aws_secret_access_key='minio123',
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region_name='us-east-1')
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r = s3.select_object_content(
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Bucket='mycsvbucket',
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Key='sampledata/TotalPopulation.csv.gz',
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ExpressionType='SQL',
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Expression="select * from s3object s where s.Location like '%United States%'",
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InputSerialization={
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'CSV': {
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"FileHeaderInfo": "USE",
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},
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'CompressionType': 'GZIP',
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},
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OutputSerialization={'CSV': {}},
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)
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for event in r['Payload']:
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if 'Records' in event:
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records = event['Records']['Payload'].decode('utf-8')
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print(records)
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elif 'Stats' in event:
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statsDetails = event['Stats']['Details']
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print("Stats details bytesScanned: ")
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print(statsDetails['BytesScanned'])
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print("Stats details bytesProcessed: ")
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print(statsDetails['BytesProcessed'])
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@ -25,6 +25,9 @@ import (
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"github.com/xwb1989/sqlparser"
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)
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// MaxExpressionLength - 256KiB
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const MaxExpressionLength = 256 * 1024
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// This function processes size so that we can calculate bytes BytesProcessed.
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func processSize(myrecord []string) int64 {
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if len(myrecord) > 0 {
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