minio/pkg/s3select/internal/parquet-go/tools/parquet2csv/parquet2csv.go

147 lines
3.1 KiB
Go

/*
* Minio Cloud Storage, (C) 2018 Minio, Inc.
*
* Licensed 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, software
* distributed under the License is distributed on an "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 under the License.
*/
package main
import (
"encoding/csv"
"fmt"
"io"
"os"
"path"
"strings"
"github.com/minio/minio-go/v6/pkg/set"
parquet "github.com/minio/minio/pkg/s3select/internal/parquet-go"
)
func getReader(name string, offset int64, length int64) (io.ReadCloser, error) {
file, err := os.Open(name)
if err != nil {
return nil, err
}
fi, err := file.Stat()
if err != nil {
return nil, err
}
if offset < 0 {
offset = fi.Size() + offset
}
if _, err = file.Seek(offset, os.SEEK_SET); err != nil {
return nil, err
}
return file, nil
}
func printUsage() {
progName := path.Base(os.Args[0])
fmt.Printf("usage: %v PARQUET-FILE [COLUMN...]\n", progName)
fmt.Println()
fmt.Printf("examples:\n")
fmt.Printf("# Convert all columns to CSV\n")
fmt.Printf("$ %v example.parquet\n", progName)
fmt.Println()
fmt.Printf("# Convert specific columns to CSV\n")
fmt.Printf("$ %v example.par firstname dob\n", progName)
fmt.Println()
}
func main() {
if len(os.Args) < 2 {
printUsage()
os.Exit(-1)
}
name := os.Args[1]
ext := path.Ext(name)
csvFilename := name + ".csv"
if ext == ".parquet" || ext == ".par" {
csvFilename = strings.TrimSuffix(name, ext) + ".csv"
}
columns := set.CreateStringSet(os.Args[2:]...)
if len(columns) == 0 {
columns = nil
}
file, err := parquet.NewReader(
func(offset, length int64) (io.ReadCloser, error) {
return getReader(name, offset, length)
},
columns,
)
if err != nil {
fmt.Printf("%v: %v\n", name, err)
os.Exit(1)
}
defer file.Close()
csvFile, err := os.OpenFile(csvFilename, os.O_RDWR|os.O_CREATE, 0755)
if err != nil {
fmt.Printf("%v: %v\n", csvFilename, err)
os.Exit(1)
}
defer csvFile.Close()
csvWriter := csv.NewWriter(csvFile)
defer csvWriter.Flush()
headerWritten := false
for {
record, err := file.Read()
if err != nil {
if err != io.EOF {
fmt.Printf("%v: %v\n", name, err)
os.Exit(1)
}
break
}
if !headerWritten {
var csvRecord []string
record.Range(func(name string, value parquet.Value) bool {
csvRecord = append(csvRecord, name)
return true
})
if err = csvWriter.Write(csvRecord); err != nil {
fmt.Printf("%v: %v\n", csvFilename, err)
os.Exit(1)
}
headerWritten = true
}
var csvRecord []string
record.Range(func(name string, value parquet.Value) bool {
csvRecord = append(csvRecord, fmt.Sprintf("%v", value.Value))
return true
})
if err = csvWriter.Write(csvRecord); err != nil {
fmt.Printf("%v: %v\n", csvFilename, err)
os.Exit(1)
}
}
}