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/*
* 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 encoding
import (
"github.com/minio/minio/pkg/s3select/internal/parquet-go/common"
"github.com/minio/minio/pkg/s3select/internal/parquet-go/gen-go/parquet"
)
// RLEDictEncode encodes values specified in https://github.com/apache/parquet-format/blob/master/Encodings.md#dictionary-encoding-plain_dictionary--2-and-rle_dictionary--8 and returns dictionary page data and data page data.
//
// Dictionary page data contains PLAIN encodeed slice of uniquely fully defined non-nil values.
// Data page data contains RLE/Bit-Packed Hybrid encoded indices of fully defined non-nil values.
//
// Supported Types: BOOLEAN, INT32, INT64, FLOAT, DOUBLE, BYTE_ARRAY
func RLEDictEncode(values []interface{}, parquetType parquet.Type, bitWidth int32) (dictPageData, dataPageData []byte, dictValueCount int32, indexBitWidth uint8) {
var definedValues []interface{}
var indices []int32
valueIndexMap := make(map[interface{}]int32)
j := 0
for i := 0; i < len(values); i = j {
for j = i; j < len(values); j++ {
value := values[j]
if value == nil {
continue
}
index, found := valueIndexMap[value]
if !found {
index = int32(len(definedValues))
definedValues = append(definedValues, value)
valueIndexMap[value] = index
}
indices = append(indices, index)
}
}
indexBitWidth = uint8(common.BitWidth(uint64(indices[len(indices)-1])))
dictPageData = PlainEncode(common.ToSliceValue(definedValues, parquetType), parquetType)
dataPageData = RLEBitPackedHybridEncode(indices, int32(indexBitWidth), parquet.Type_INT32)
return dictPageData, dataPageData, int32(len(definedValues)), indexBitWidth
}