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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.drill.exec.store.parquet;
import org.apache.commons.lang3.mutable.MutableLong;
import org.apache.drill.common.expression.SchemaPath;
import org.apache.drill.common.types.TypeProtos;
import org.apache.drill.exec.physical.base.GroupScan;
import org.apache.hadoop.fs.Path;
import org.apache.parquet.schema.OriginalType;
import org.apache.parquet.schema.PrimitiveType;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import static org.apache.drill.exec.store.parquet.metadata.MetadataBase.ColumnMetadata;
import static org.apache.drill.exec.store.parquet.metadata.MetadataBase.ParquetTableMetadataBase;
import static org.apache.drill.exec.store.parquet.metadata.Metadata_V3.ColumnTypeMetadata_v3;
import static org.apache.drill.exec.store.parquet.metadata.Metadata_V3.ParquetTableMetadata_v3;
/**
* Holds common statistics about data in parquet group scan,
* including information about total row count, columns counts, partition columns.
*/
public class ParquetGroupScanStatistics {
// map from file names to maps of column name to partition value mappings
private Map<Path, Map<SchemaPath, Object>> partitionValueMap;
// only for partition columns : value is unique for each partition
private Map<SchemaPath, TypeProtos.MajorType> partitionColTypeMap;
// total number of non-null value for each column in parquet files
private Map<SchemaPath, MutableLong> columnValueCounts;
// total number of rows (obtained from parquet footer)
private long rowCount;
public ParquetGroupScanStatistics(List<RowGroupInfo> rowGroupInfos, ParquetTableMetadataBase parquetTableMetadata) {
collect(rowGroupInfos, parquetTableMetadata);
}
public ParquetGroupScanStatistics(ParquetGroupScanStatistics that) {
this.partitionValueMap = new HashMap<>(that.partitionValueMap);
this.partitionColTypeMap = new HashMap<>(that.partitionColTypeMap);
this.columnValueCounts = new HashMap<>(that.columnValueCounts);
this.rowCount = that.rowCount;
}
public long getColumnValueCount(SchemaPath column) {
MutableLong count = columnValueCounts.get(column);
return count != null ? count.getValue() : 0;
}
public List<SchemaPath> getPartitionColumns() {
return new ArrayList<>(partitionColTypeMap.keySet());
}
public TypeProtos.MajorType getTypeForColumn(SchemaPath schemaPath) {
return partitionColTypeMap.get(schemaPath);
}
public long getRowCount() {
return rowCount;
}
public Object getPartitionValue(Path path, SchemaPath column) {
return partitionValueMap.get(path).get(column);
}
public void collect(List<RowGroupInfo> rowGroupInfos, ParquetTableMetadataBase parquetTableMetadata) {
resetHolders();
boolean first = true;
for (RowGroupInfo rowGroup : rowGroupInfos) {
long rowCount = rowGroup.getRowCount();
for (ColumnMetadata column : rowGroup.getColumns()) {
SchemaPath schemaPath = SchemaPath.getCompoundPath(column.getName());
MutableLong emptyCount = new MutableLong();
MutableLong previousCount = columnValueCounts.putIfAbsent(schemaPath, emptyCount);
if (previousCount == null) {
previousCount = emptyCount;
}
if (previousCount.longValue() != GroupScan.NO_COLUMN_STATS && column.isNumNullsSet()) {
previousCount.add(rowCount - column.getNulls());
} else {
previousCount.setValue(GroupScan.NO_COLUMN_STATS);
}
boolean partitionColumn = checkForPartitionColumn(column, first, rowCount, parquetTableMetadata);
if (partitionColumn) {
Map<SchemaPath, Object> map = partitionValueMap.computeIfAbsent(rowGroup.getPath(), key -> new HashMap<>());
Object value = map.get(schemaPath);
Object currentValue = column.getMaxValue();
if (value != null) {
if (value != currentValue) {
partitionColTypeMap.remove(schemaPath);
}
} else {
// the value of a column with primitive type can not be null,
// so checks that there are really null value and puts it to the map
if (rowCount == column.getNulls()) {
map.put(schemaPath, null);
} else {
map.put(schemaPath, currentValue);
}
}
} else {
partitionColTypeMap.remove(schemaPath);
}
}
this.rowCount += rowGroup.getRowCount();
first = false;
}
}
/**
* Re-init holders eigther during first instance creation or statistics update based on updated list of row groups.
*/
private void resetHolders() {
this.partitionValueMap = new HashMap<>();
this.partitionColTypeMap = new HashMap<>();
this.columnValueCounts = new HashMap<>();
this.rowCount = 0;
}
/**
* When reading the very first footer, any column is a potential partition column. So for the first footer, we check
* every column to see if it is single valued, and if so, add it to the list of potential partition columns. For the
* remaining footers, we will not find any new partition columns, but we may discover that what was previously a
* potential partition column now no longer qualifies, so it needs to be removed from the list.
*
* @param columnMetadata column metadata
* @param first if columns first appears in row group
* @param rowCount row count
* @param parquetTableMetadata parquet table metadata
*
* @return whether column is a potential partition column
*/
private boolean checkForPartitionColumn(ColumnMetadata columnMetadata,
boolean first,
long rowCount,
ParquetTableMetadataBase parquetTableMetadata) {
SchemaPath schemaPath = SchemaPath.getCompoundPath(columnMetadata.getName());
final PrimitiveType.PrimitiveTypeName primitiveType;
final OriginalType originalType;
int precision = 0;
int scale = 0;
if (parquetTableMetadata.hasColumnMetadata()) {
// only ColumnTypeMetadata_v3 stores information about scale and precision
if (parquetTableMetadata instanceof ParquetTableMetadata_v3) {
ColumnTypeMetadata_v3 columnTypeInfo = ((ParquetTableMetadata_v3) parquetTableMetadata)
.getColumnTypeInfo(columnMetadata.getName());
scale = columnTypeInfo.scale;
precision = columnTypeInfo.precision;
}
primitiveType = parquetTableMetadata.getPrimitiveType(columnMetadata.getName());
originalType = parquetTableMetadata.getOriginalType(columnMetadata.getName());
} else {
primitiveType = columnMetadata.getPrimitiveType();
originalType = columnMetadata.getOriginalType();
}
if (first) {
if (hasSingleValue(columnMetadata, rowCount)) {
partitionColTypeMap.put(schemaPath, ParquetReaderUtility.getType(primitiveType, originalType, scale, precision));
return true;
} else {
return false;
}
} else {
if (!partitionColTypeMap.keySet().contains(schemaPath)) {
return false;
} else {
if (!hasSingleValue(columnMetadata, rowCount)) {
partitionColTypeMap.remove(schemaPath);
return false;
}
if (!ParquetReaderUtility.getType(primitiveType, originalType, scale, precision).equals(partitionColTypeMap.get(schemaPath))) {
partitionColTypeMap.remove(schemaPath);
return false;
}
}
}
return true;
}
/**
* Checks that the column chunk has a single value.
* ColumnMetadata will have a non-null value iff the minValue and
* the maxValue for the rowgroup are the same.
*
* @param columnChunkMetaData metadata to check
* @param rowCount rows count in column chunk
*
* @return true if column has single value
*/
private boolean hasSingleValue(ColumnMetadata columnChunkMetaData, long rowCount) {
return (columnChunkMetaData != null) && (columnChunkMetaData.hasSingleValue(rowCount));
}
}
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