adarshsanjeev commented on code in PR #15917:
URL: https://github.com/apache/druid/pull/15917#discussion_r1494178033
##########
processing/src/main/java/org/apache/druid/frame/read/columnar/StringFrameColumnReader.java:
##########
@@ -231,7 +201,9 @@ private static long getStartOfStringDataSection(
final int totalNumValues;
if (multiValue) {
- totalNumValues =
adjustCumulativeRowLength(getCumulativeRowLength(memory, numRows - 1));
+ totalNumValues = FrameColumnReaderUtils.adjustCumulativeRowLength(
Review Comment:
Should this be changed to `getAdjustedCumulativeRowLength` instead?
##########
processing/src/main/java/org/apache/druid/frame/read/columnar/StringFrameColumnReader.java:
##########
@@ -489,15 +461,24 @@ private String getString(final int index)
private Object getRowAsObject(final int physicalRow, final boolean decode)
{
if (multiValue) {
- final int cumulativeRowLength = getCumulativeRowLength(memory,
physicalRow);
+ final int cumulativeRowLength =
FrameColumnReaderUtils.getCumulativeRowLength(
+ memory,
+ getStartOfCumulativeLengthSection(),
+ physicalRow
+ );
final int rowLength;
- if (isNullRow(cumulativeRowLength)) {
+ if (FrameColumnReaderUtils.isNullRow(cumulativeRowLength)) {
return null;
} else if (physicalRow == 0) {
rowLength = cumulativeRowLength;
} else {
- rowLength = cumulativeRowLength -
adjustCumulativeRowLength(getCumulativeRowLength(memory, physicalRow - 1));
+ rowLength = cumulativeRowLength -
FrameColumnReaderUtils.adjustCumulativeRowLength(
Review Comment:
Should this also be getAdjustedRowLength since the function exists?
##########
processing/src/main/java/org/apache/druid/frame/read/columnar/FloatArrayFrameColumnReader.java:
##########
@@ -0,0 +1,64 @@
+/*
+ * 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.druid.frame.read.columnar;
+
+import com.google.common.math.LongMath;
+import org.apache.datasketches.memory.Memory;
+import org.apache.druid.frame.Frame;
+import org.apache.druid.frame.write.columnar.FrameColumnWriters;
+import org.apache.druid.segment.column.ColumnType;
+
+/**
+ * Reaaers for columns written by {@link
org.apache.druid.frame.write.columnar.LongArrayFrameColumnWriter}
Review Comment:
nit: spelling
##########
processing/src/main/java/org/apache/druid/frame/write/columnar/NumericArrayFrameColumnWriter.java:
##########
@@ -0,0 +1,223 @@
+/*
+ * 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.druid.frame.write.columnar;
+
+import org.apache.datasketches.memory.WritableMemory;
+import org.apache.druid.error.DruidException;
+import org.apache.druid.frame.allocation.AppendableMemory;
+import org.apache.druid.frame.allocation.MemoryAllocator;
+import org.apache.druid.frame.allocation.MemoryRange;
+import org.apache.druid.frame.write.FrameWriterUtils;
+import org.apache.druid.segment.ColumnValueSelector;
+
+import java.util.List;
+
+/**
+ * Parent class for the family of writers writing numeric arrays in columnar
frames. Since the numeric primitives are
+ * fixed width, we don't need to store the width of each element. The memory
layout of a column written by this writer
+ * is as follows:
+ *
+ * n : Total number of rows
+ * k : Total number of elements in all the rows, cumulative
+ *
+ * | Section | Length of the section | Denotion
|
+ *
|---------|-----------------------|--------------------------------------------------------------------------------------|
+ * | 0 | 1 | typeCode
|
+ * | 1 | n * Integer.BYTES | n integers, where i-th integer
represents the cumulative length of the array |
+ * | 2 | k * Byte.BYTES | k bytes, where i-th byte represent
whether the i-th value from the start is null |
+ * | 3 | k * ELEMENT_SIZE | k values, each representing the
element, or null equivalent value (e.g 0 for double) |
+ *
+ * Note on cumulative lengths stored in section 1: Cumulative lengths are
stored so that its fast to offset into the
+ * elements of the array. We also use negative cumulative length to denote
that the array itself is null (as opposed to
+ * individual elements being null, which we store in section 2)
Review Comment:
Thanks for the detailed doc! This made it a lot easier to follow
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