Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/9774#discussion_r45274882
--- Diff:
sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/UnsafeRowParquetRecordReader.java
---
@@ -0,0 +1,613 @@
+/*
+ * 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.spark.sql.execution.datasources.parquet;
+
+import static org.apache.parquet.column.ValuesType.DEFINITION_LEVEL;
+import static org.apache.parquet.column.ValuesType.REPETITION_LEVEL;
+import static org.apache.parquet.column.ValuesType.VALUES;
+
+import org.apache.hadoop.mapreduce.InputSplit;
+import org.apache.hadoop.mapreduce.TaskAttemptContext;
+import org.apache.parquet.Preconditions;
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.parquet.column.Dictionary;
+import org.apache.parquet.column.page.*;
+import org.apache.parquet.column.Encoding;
+import org.apache.parquet.column.values.ValuesReader;
+import org.apache.parquet.io.api.Binary;
+import org.apache.parquet.schema.OriginalType;
+import org.apache.parquet.schema.PrimitiveType;
+import org.apache.parquet.schema.Type;
+import org.apache.spark.sql.catalyst.expressions.UnsafeRow;
+import org.apache.spark.sql.types.Decimal;
+import org.apache.spark.unsafe.Platform;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.*;
+
+/**
+ * A specialized RecordReader that reads into UnsafeRows directly using
the Parquet column APIs.
+ *
+ * This is somewhat based on parquet-mr's ColumnReader.
+ *
+ * TODO: handle complex types, decimal requiring more than 8 bytes, INT96.
Schema mismatch.
+ * All of these can be handled efficiently and easily with codegen.
+ */
+public class UnsafeRowParquetRecordReader extends
SpecificParquetRecordReaderBase<UnsafeRow> {
+ /**
+ * Batch of unsafe rows that we assemble and the current index we've
returned. Everytime this
+ * batch is used up (batchIdx == numBatched), we populated the batch.
+ */
+ private UnsafeRow[] rows = new UnsafeRow[64];
+ private int batchIdx = 0;
+ private int numBatched = 0;
+
+ /**
+ * Used to write variable lenght columns. Same length as `rows`.
+ */
+ private RowWriter[] rowWriters = null;
+
+ /**
+ * True if the row contains variable length fields.
+ */
+ private boolean containsVarLenFields;
+
+ /**
+ * For each request column, the reader to read this column.
+ * columnsReaders[i] populated the UnsafeRow's attribute at i.
+ */
+ private ColumnReader[] columnReaders;
+
+ /**
+ * The number of rows that have been returned.
+ */
+ private long rowsReturned;
+
+ /**
+ * The number of rows that have been reading, including the current in
flight row group.
+ */
+ private long totalCountLoadedSoFar = 0;
+
+ /**
+ * For each column, the annotated original type.
+ */
+ OriginalType[] originalTypes;
+
+ /**
+ * Implementation of RecordReader API.
+ */
+ @Override
+ public void initialize(InputSplit inputSplit, TaskAttemptContext
taskAttemptContext)
+ throws IOException, InterruptedException {
+ super.initialize(inputSplit, taskAttemptContext);
+
+ /**
+ * Check that the requested schema is supported.
+ */
+ int numVarLenFields = 0;
+ originalTypes = new OriginalType[requestedSchema.getFieldCount()];
+ for (int i = 0; i < requestedSchema.getFieldCount(); ++i) {
+ Type t = requestedSchema.getFields().get(i);
+ if (!t.isPrimitive()) throw new IOException("Complex types not
supported.");
+ PrimitiveType primitiveType = t.asPrimitiveType();
+
+ originalTypes[i] = t.getOriginalType();
+
+ // TODO: Be extremely cautious in what is supported. Expand this.
+ if (originalTypes[i] != null && originalTypes[i] !=
OriginalType.DECIMAL &&
+ originalTypes[i] != OriginalType.UTF8 && originalTypes[i] !=
OriginalType.DATE) {
+ throw new IOException("Unsupported type: " + t);
+ }
+ if (originalTypes[i] == OriginalType.DECIMAL &&
+ primitiveType.getDecimalMetadata().getPrecision() >
+ CatalystSchemaConverter.MAX_PRECISION_FOR_INT64()) {
+ throw new IOException("Decimal with high precision is not
supported.");
+ }
+ if (primitiveType.getPrimitiveTypeName() ==
PrimitiveType.PrimitiveTypeName.INT96) {
+ throw new IOException("Int96 not supported.");
+ }
+ ColumnDescriptor fd =
fileSchema.getColumnDescription(requestedSchema.getPaths().get(i));
+ if (!fd.equals(requestedSchema.getColumns().get(i))) {
+ throw new IOException("Schema evolution not supported.");
+ }
+
+ if (primitiveType.getPrimitiveTypeName() ==
PrimitiveType.PrimitiveTypeName.BINARY) {
+ ++numVarLenFields;
+ }
+ }
+
+ int rowByteSize =
UnsafeRow.calculateBitSetWidthInBytes(requestedSchema.getFieldCount());
+ rowByteSize += 8 * requestedSchema.getFieldCount();
+ containsVarLenFields = numVarLenFields > 0;
+ rowWriters = new RowWriter[rows.length];
+
+ for (int i = 0; i < rows.length; ++i) {
+ rows[i] = new UnsafeRow();
+ rowWriters[i] = new RowWriter(
+ rows[i],
+ requestedSchema.getFieldCount(),
+ rowByteSize,
+ numVarLenFields);
+ }
+ }
+
+ @Override
+ public boolean nextKeyValue() throws IOException, InterruptedException {
+ if (batchIdx >= numBatched) {
+ if (!loadBatch()) return false;
+ }
+ ++batchIdx;
+ return true;
+ }
+
+ @Override
+ public UnsafeRow getCurrentValue() throws IOException,
InterruptedException {
+ return rows[batchIdx - 1];
+ }
+
+ @Override
+ public float getProgress() throws IOException, InterruptedException {
+ return (float) rowsReturned / totalRowCount;
+ }
+
+ /**
+ * Decodes a batch of values into `rows`. This function is the hot path.
+ */
+ private boolean loadBatch() throws IOException {
+ // no more records left
+ if (rowsReturned >= totalRowCount) { return false; }
+ checkEndOfRowGroup();
+
+ int num = (int)Math.min(rows.length, totalCountLoadedSoFar -
rowsReturned);
+ rowsReturned += num;
+
+ if (containsVarLenFields) {
+ for (int i = 0; i < rowWriters.length; ++i) {
+ rowWriters[i].reset();
+ }
+ }
+
+ for (int i = 0; i < columnReaders.length; ++i) {
+ switch (columnReaders[i].descriptor.getType()) {
+ case BOOLEAN:
+ decodeBooleanBatch(i, num);
+ break;
+ case INT32:
+ if (originalTypes[i] == OriginalType.DECIMAL) {
+ decodeIntAsDecimalBatch(i, num);
+ } else {
+ decodeIntBatch(i, num);
+ }
+ break;
+ case INT64:
+ Preconditions.checkState(originalTypes[i] == null
+ || originalTypes[i] == OriginalType.DECIMAL,
+ "Unexpected original type: " + originalTypes[i]);
+ decodeLongBatch(i, num);
+ break;
+ case FLOAT:
+ decodeFloatBatch(i, num);
+ break;
+ case DOUBLE:
+ decodeDoubleBatch(i, num);
+ break;
+ case BINARY:
+ decodeBinaryBatch(i, num);
+ break;
+ case FIXED_LEN_BYTE_ARRAY:
+ Preconditions.checkState(originalTypes[i] ==
OriginalType.DECIMAL,
+ "Unexpected original type: " + originalTypes[i]);
+ decodeFixedLenArrayAsDecimalBatch(i, num);
+ break;
+ case INT96:
+ throw new IOException("Unsupported " +
columnReaders[i].descriptor.getType());
+ }
+ numBatched = num;
+ batchIdx = 0;
+ }
+ return true;
+ }
+
+ private void decodeBooleanBatch(int col, int num) throws IOException {
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ rows[n].setBoolean(col, columnReaders[col].nextBoolean());
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ private void decodeIntBatch(int col, int num) throws IOException {
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ rows[n].setInt(col, columnReaders[col].nextInt());
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ private void decodeIntAsDecimalBatch(int col, int num) throws
IOException {
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ // Since this is stored as an INT, it is always a compact decimal.
Just set it as a long.
+ rows[n].setLong(col, columnReaders[col].nextInt());
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ private void decodeLongBatch(int col, int num) throws IOException {
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ rows[n].setLong(col, columnReaders[col].nextLong());
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ private void decodeFloatBatch(int col, int num) throws IOException {
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ rows[n].setFloat(col, columnReaders[col].nextFloat());
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ private void decodeDoubleBatch(int col, int num) throws IOException {
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ rows[n].setDouble(col, columnReaders[col].nextDouble());
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ private void decodeBinaryBatch(int col, int num) throws IOException {
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ Binary b = columnReaders[col].nextBinary();
+ rowWriters[n].appendBytes(col, b.toByteBuffer());
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ private void decodeFixedLenArrayAsDecimalBatch(int col, int num) throws
IOException {
+ PrimitiveType type =
requestedSchema.getFields().get(col).asPrimitiveType();
+ int precision = type.getDecimalMetadata().getPrecision();
+ int scale = type.getDecimalMetadata().getScale();
+ Preconditions.checkState(precision <=
CatalystSchemaConverter.MAX_PRECISION_FOR_INT64(),
+ "Unsupported precision.");
+
+ for (int n = 0; n < num; ++n) {
+ if (columnReaders[col].next()) {
+ Binary v = columnReaders[col].nextBinary();
+ // Constructs a `Decimal` with an unscaled `Long` value if
possible.
+ long unscaled = CatalystRowConverter.binaryToUnscaledLong(v);
+ rows[n].setDecimal(col, Decimal.apply(unscaled, precision, scale),
precision);
+ } else {
+ rows[n].setNullAt(col);
+ }
+ }
+ }
+
+ /**
+ * Writer to append variable length data in rows. This should be merged
with UnsafeRowWriter.
+ * UnsafeRowWriter currently has a few inefficiencies so this is used
instead. In particular
+ * it does not have a reference to an UnsafeRow meaning that there is no
good way to reuse
+ * a UnsafeRow object.
+ */
+ private static final class RowWriter {
+ private static final int DEFAULT_VAR_LEN_SIZE = 32;
+ UnsafeRow row;
+ final int fieldCount;
+ final int fixedSize;
+ int variableSize;
+ int variableOffset;
+ byte[] buffer;
+
+ RowWriter(UnsafeRow row, int fieldCount, int rowByteSize, int
numVarLenFields) {
+ this.row = row;
+ this.fieldCount = fieldCount;
+ this.fixedSize = rowByteSize;
+ this.variableSize = numVarLenFields * DEFAULT_VAR_LEN_SIZE;
+ this.buffer = new byte[fixedSize + variableSize];
+ row.pointTo(buffer, fieldCount, fixedSize + variableSize);
+ }
+
+ /**
+ * Resets variable state to zero.
+ */
+ void reset() {
+ variableOffset = 0;
+ }
+
+ /**
+ * Appends `bytes` to `col`. This populates the value in the fixed
portion for `col` and
+ * appends the var length data.
+ */
+ void appendBytes(int col, ByteBuffer bytes) {
+ // grow the buffer before writing data.
+ int len = bytes.limit() - bytes.position();
+ if (variableOffset + len > variableSize) {
+ int newVariableSize = variableSize * 2;
+ byte[] newBuffer = new byte[fixedSize + newVariableSize];
+ Platform.copyMemory(buffer, Platform.BYTE_ARRAY_OFFSET, newBuffer,
+ Platform.BYTE_ARRAY_OFFSET, buffer.length);
+ buffer = newBuffer;
+ variableSize = newVariableSize;
+ row.pointTo(buffer, fieldCount, fixedSize + variableSize);
+ }
+
+ Platform.copyMemory(bytes.array(), Platform.BYTE_ARRAY_OFFSET +
bytes.position(),
+ buffer, Platform.BYTE_ARRAY_OFFSET + fixedSize + variableOffset,
len);
+ long offset = (fixedSize + variableOffset);
+ row.setLong(col, offset << 32 | len);
+ variableOffset += len;
+ }
+ }
+
+ /**
+ *
+ * Decoder to return values from a single column.
+ */
+ private static final class ColumnReader {
+ /**
+ * Total number of values read.
+ */
+ private long valuesRead;
+
+ /**
+ * value that indicates the end of the current page. That is,
+ * if valuesRead == endOfPageValueCount, we are at the end of the page.
+ */
+ private long endOfPageValueCount;
+
+ /**
+ * The dictionary, if this column has dictionary encoding.
+ */
+ private final Dictionary dictionary;
+
+ /**
+ * If true, the current page is dictionary encoded.
+ */
+ private boolean useDictionary;
+
+ /**
+ * Maximum definition level for this column.
+ */
+ private final int maxDefLevel;
+
+ /**
+ * Repetition/Definition/Value readers.
+ */
+ private IntIterator repetitionLevelColumn;
+ private IntIterator definitionLevelColumn;
+ private ValuesReader dataColumn;
+
+ /**
+ * Total number of values in this column (in this row group).
+ */
+ private final long totalValueCount;
+
+ /**
+ * Total values in the current page.
+ */
+ private int pageValueCount;
+
+ private final PageReader pageReader;
+ private final ColumnDescriptor descriptor;
+
+ public ColumnReader(ColumnDescriptor descriptor, PageReader pageReader)
+ throws IOException {
+ this.descriptor = descriptor;
+ this.pageReader = pageReader;
+ this.maxDefLevel = descriptor.getMaxDefinitionLevel();
+
+ DictionaryPage dictionaryPage = pageReader.readDictionaryPage();
+ if (dictionaryPage != null) {
+ try {
+ this.dictionary =
dictionaryPage.getEncoding().initDictionary(descriptor, dictionaryPage);
+ this.useDictionary = true;
+ } catch (IOException e) {
+ throw new IOException("could not decode the dictionary for " +
descriptor, e);
+ }
+ } else {
+ this.dictionary = null;
+ this.useDictionary = false;
+ }
+ this.totalValueCount = pageReader.getTotalValueCount();
+ if (totalValueCount == 0) {
+ throw new IOException("totalValueCount == 0");
+ }
+ }
+
+ /**
+ * TODO: Hoist the useDictionary branch to decode*Batch and make the
batch page aligned.
+ */
+ public boolean nextBoolean() {
+ if (!useDictionary) {
+ return dataColumn.readBoolean();
+ } else {
+ return
dictionary.decodeToBoolean(dataColumn.readValueDictionaryId());
+ }
+ }
+
+ public int nextInt() {
+ if (!useDictionary) {
+ return dataColumn.readInteger();
+ } else {
+ return dictionary.decodeToInt(dataColumn.readValueDictionaryId());
+ }
+ }
+
+ public long nextLong() {
+ if (!useDictionary) {
+ return dataColumn.readLong();
+ } else {
+ return dictionary.decodeToLong(dataColumn.readValueDictionaryId());
+ }
+ }
+
+ public float nextFloat() {
+ if (!useDictionary) {
+ return dataColumn.readFloat();
+ } else {
+ return
dictionary.decodeToFloat(dataColumn.readValueDictionaryId());
+ }
+ }
+
+ public double nextDouble() {
+ if (!useDictionary) {
+ return dataColumn.readDouble();
+ } else {
+ return
dictionary.decodeToDouble(dataColumn.readValueDictionaryId());
+ }
+ }
+
+ public Binary nextBinary() {
+ if (!useDictionary) {
+ return dataColumn.readBytes();
+ } else {
+ return
dictionary.decodeToBinary(dataColumn.readValueDictionaryId());
+ }
+ }
+
+ /**
+ * Advances to the next value. Returns true if the value is non-null.
+ */
+ private boolean next() throws IOException {
+ if (valuesRead >= endOfPageValueCount) {
+ if (valuesRead >= totalValueCount) {
+ // How do we get here? Throw end of stream exception?
+ return false;
+ }
+ readPage();
+ }
+ ++valuesRead;
+ // TODO: Don't read for flat schemas
+ //repetitionLevel = repetitionLevelColumn.nextInt();
+ return definitionLevelColumn.nextInt() == maxDefLevel;
+ }
+
+ private void readPage() throws IOException {
+ DataPage page = pageReader.readPage();
+ // TODO: Why is this a visitor?
+ page.accept(new DataPage.Visitor<Void>() {
+ @Override
+ public Void visit(DataPageV1 dataPageV1) {
+ try {
+ readPageV1(dataPageV1);
+ return null;
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ @Override
+ public Void visit(DataPageV2 dataPageV2) {
+ try {
+ readPageV2(dataPageV2);
+ return null;
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+ });
+ }
+
+ private void initDataReader(Encoding dataEncoding, byte[] bytes, int
offset, int valueCount)
+ throws IOException {
+ this.pageValueCount = valueCount;
+ this.endOfPageValueCount = valuesRead + pageValueCount;
+ if (dataEncoding.usesDictionary()) {
+ if (dictionary == null) {
+ throw new IOException(
+ "could not read page in col " + descriptor +
+ " as the dictionary was missing for encoding " +
dataEncoding);
+ }
+ this.dataColumn = dataEncoding.getDictionaryBasedValuesReader(
+ descriptor, VALUES, dictionary);
+ this.useDictionary = true;
+ } else {
+ this.dataColumn = dataEncoding.getValuesReader(descriptor, VALUES);
+ this.useDictionary = false;
+ }
+
+ try {
+ dataColumn.initFromPage(pageValueCount, bytes, offset);
+ } catch (IOException e) {
+ throw new IOException("could not read page in col " + descriptor,
e);
+ }
+ }
+
+ private void readPageV1(DataPageV1 page) throws IOException {
+ ValuesReader rlReader =
page.getRlEncoding().getValuesReader(descriptor, REPETITION_LEVEL);
+ ValuesReader dlReader =
page.getDlEncoding().getValuesReader(descriptor, DEFINITION_LEVEL);
+ this.repetitionLevelColumn = new ValuesReaderIntIterator(rlReader);
+ this.definitionLevelColumn = new ValuesReaderIntIterator(dlReader);
+ try {
+ byte[] bytes = page.getBytes().toByteArray();
+ rlReader.initFromPage(pageValueCount, bytes, 0);
+ int next = rlReader.getNextOffset();
+ dlReader.initFromPage(pageValueCount, bytes, next);
+ next = dlReader.getNextOffset();
+ initDataReader(page.getValueEncoding(), bytes, next,
page.getValueCount());
+ } catch (IOException e) {
+ throw new IOException("could not read page " + page + " in col " +
descriptor, e);
+ }
+ }
+
+ private void readPageV2(DataPageV2 page) throws IOException {
+ this.repetitionLevelColumn =
createRLEIterator(descriptor.getMaxRepetitionLevel(),
+ page.getRepetitionLevels(), descriptor);
+ this.definitionLevelColumn =
createRLEIterator(descriptor.getMaxDefinitionLevel(),
+ page.getDefinitionLevels(), descriptor);
+ try {
+ initDataReader(page.getDataEncoding(),
page.getData().toByteArray(), 0,
+ page.getValueCount());
+ } catch (IOException e) {
+ throw new IOException("could not read page " + page + " in col " +
descriptor, e);
+ }
+ }
+ }
+
+ private void checkEndOfRowGroup() throws IOException {
+ if (rowsReturned != totalCountLoadedSoFar) return;
+ PageReadStore pages = reader.readNextRowGroup();
+ if (pages == null) {
+ throw new IOException("expecting more rows but reached last block.
Read "
+ + rowsReturned + " out of " + totalRowCount);
+ }
+ List<ColumnDescriptor> columns = requestedSchema.getColumns();
--- End diff --
nvm, the ColumnReader is related to pages
---
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