160 lines
3.8 KiB
Go
160 lines
3.8 KiB
Go
/*
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* Minio Cloud Storage, (C) 2018 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package parquet
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import (
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"errors"
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"io"
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"strings"
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"git.apache.org/thrift.git/lib/go/thrift"
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"github.com/minio/minio-go/v7/pkg/set"
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"github.com/minio/minio/pkg/s3select/internal/parquet-go/gen-go/parquet"
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)
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func getColumns(
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rowGroup *parquet.RowGroup,
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columnNames set.StringSet,
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schemaElements []*parquet.SchemaElement,
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getReaderFunc GetReaderFunc,
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) (nameColumnMap map[string]*column, err error) {
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nameIndexMap := make(map[string]int)
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for colIndex, columnChunk := range rowGroup.GetColumns() {
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meta := columnChunk.GetMetaData()
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if meta == nil {
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return nil, errors.New("parquet: column metadata missing")
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}
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columnName := strings.Join(meta.GetPathInSchema(), ".")
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if columnNames != nil && !columnNames.Contains(columnName) {
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continue
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}
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// Ignore column spanning into another file.
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if columnChunk.GetFilePath() != "" {
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continue
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}
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offset := meta.GetDataPageOffset()
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if meta.DictionaryPageOffset != nil {
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offset = meta.GetDictionaryPageOffset()
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}
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size := meta.GetTotalCompressedSize()
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if size < 0 {
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return nil, errors.New("parquet: negative compressed size")
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}
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rc, err := getReaderFunc(offset, size)
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if err != nil {
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return nil, err
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}
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thriftReader := thrift.NewTBufferedTransport(thrift.NewStreamTransportR(rc), int(size))
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if nameColumnMap == nil {
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nameColumnMap = make(map[string]*column)
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}
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nameColumnMap[columnName] = &column{
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name: columnName,
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metadata: meta,
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schemaElements: schemaElements,
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rc: rc,
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thriftReader: thriftReader,
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valueType: meta.GetType(),
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}
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// First element of []*parquet.SchemaElement from parquet file metadata is 'schema'
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// which is always skipped, hence colIndex + 1 is valid.
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nameIndexMap[columnName] = colIndex + 1
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}
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for name := range nameColumnMap {
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nameColumnMap[name].nameIndexMap = nameIndexMap
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}
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return nameColumnMap, nil
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}
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type column struct {
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name string
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endOfValues bool
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valueIndex int
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valueType parquet.Type
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metadata *parquet.ColumnMetaData
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schemaElements []*parquet.SchemaElement
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nameIndexMap map[string]int
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dictPage *page
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dataTable *table
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rc io.ReadCloser
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thriftReader *thrift.TBufferedTransport
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}
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func (column *column) close() (err error) {
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if column.rc != nil {
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err = column.rc.Close()
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column.rc = nil
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}
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return err
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}
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func (column *column) readPage() {
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page, _, _, err := readPage(
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column.thriftReader,
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column.metadata,
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column.nameIndexMap,
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column.schemaElements,
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)
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if err != nil {
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column.endOfValues = true
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return
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}
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if page.Header.GetType() == parquet.PageType_DICTIONARY_PAGE {
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column.dictPage = page
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column.readPage()
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return
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}
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page.decode(column.dictPage)
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if column.dataTable == nil {
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column.dataTable = newTableFromTable(page.DataTable)
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}
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column.dataTable.Merge(page.DataTable)
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}
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func (column *column) read() (value interface{}, valueType parquet.Type) {
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if column.dataTable == nil {
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column.readPage()
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column.valueIndex = 0
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}
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if column.endOfValues {
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return nil, column.metadata.GetType()
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}
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value = column.dataTable.Values[column.valueIndex]
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column.valueIndex++
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if len(column.dataTable.Values) == column.valueIndex {
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column.dataTable = nil
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}
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return value, column.metadata.GetType()
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}
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