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minio/pkg/s3select/parquet/reader.go

101 lines
2.6 KiB

/*
* Minio Cloud Storage, (C) 2019 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 parquet
import (
"io"
"github.com/minio/minio/pkg/s3select/json"
"github.com/minio/minio/pkg/s3select/sql"
parquetgo "github.com/minio/parquet-go"
parquetgen "github.com/minio/parquet-go/gen-go/parquet"
)
// Reader - Parquet record reader for S3Select.
type Reader struct {
args *ReaderArgs
file *parquetgo.File
}
// Read - reads single record.
func (r *Reader) Read() (sql.Record, error) {
parquetRecord, err := r.file.Read()
if err != nil {
if err != io.EOF {
return nil, errParquetParsingError(err)
}
return nil, err
}
record := json.NewRecord()
for name, v := range parquetRecord {
if v.Value == nil {
if err = record.Set(name, sql.NewNull()); err != nil {
return nil, errParquetParsingError(err)
}
continue
}
var value *sql.Value
switch v.Type {
case parquetgen.Type_BOOLEAN:
value = sql.NewBool(v.Value.(bool))
case parquetgen.Type_INT32:
value = sql.NewInt(int64(v.Value.(int32)))
case parquetgen.Type_INT64:
value = sql.NewInt(v.Value.(int64))
case parquetgen.Type_FLOAT:
value = sql.NewFloat(float64(v.Value.(float32)))
case parquetgen.Type_DOUBLE:
value = sql.NewFloat(v.Value.(float64))
case parquetgen.Type_INT96, parquetgen.Type_BYTE_ARRAY, parquetgen.Type_FIXED_LEN_BYTE_ARRAY:
value = sql.NewString(string(v.Value.([]byte)))
default:
return nil, errParquetParsingError(nil)
}
if err = record.Set(name, value); err != nil {
return nil, errParquetParsingError(err)
}
}
return record, nil
}
// Close - closes underlaying readers.
func (r *Reader) Close() error {
return r.file.Close()
}
// NewReader - creates new Parquet reader using readerFunc callback.
func NewReader(getReaderFunc func(offset, length int64) (io.ReadCloser, error), args *ReaderArgs) (*Reader, error) {
file, err := parquetgo.Open(getReaderFunc, nil)
if err != nil {
if err != io.EOF {
return nil, errParquetParsingError(err)
}
return nil, err
}
return &Reader{
args: args,
file: file,
}, nil
}