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https://issues.apache.org/jira/browse/PARQUET-1977?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17288983#comment-17288983
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ASF GitHub Bot commented on PARQUET-1977:
-----------------------------------------
ggershinsky commented on a change in pull request #868:
URL: https://github.com/apache/parquet-mr/pull/868#discussion_r580889480
##########
File path: parquet-hadoop/src/main/java/org/apache/parquet/hadoop/Offsets.java
##########
@@ -0,0 +1,84 @@
+/*
+ * 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.parquet.hadoop;
+
+import java.io.IOException;
+
+import org.apache.parquet.format.PageHeader;
+import org.apache.parquet.format.Util;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+import org.apache.parquet.io.SeekableInputStream;
+
+/**
+ * Class to help gather/calculate the proper values of the dictionary/first
data page offset values in a column chunk.
+ */
+class Offsets {
+
+ /**
+ * Returns the offset values for the column chunk to be written.
+ *
+ * @param input the source input stream of the column chunk
+ * @param chunk the column chunk metadata read from the source file
+ * @param newChunkStart the position of the column chunk to be written
+ * @return the offset values
+ * @throws IOException if any I/O error occurs during the reading of the
input stream
+ */
+ public static Offsets getOffsets(SeekableInputStream input,
ColumnChunkMetaData chunk, long newChunkStart)
+ throws IOException {
+ long firstDataPageOffset;
+ long dictionaryPageOffset;
+ if (chunk.hasDictionaryPage()) {
+ long dictionaryPageSize = chunk.getFirstDataPageOffset() -
chunk.getDictionaryPageOffset();
+ if (dictionaryPageSize <= 0) {
+ // The offset values might be invalid so we have to read the size of
the dictionary page
+ dictionaryPageSize = readDictionaryPageSize(input, newChunkStart);
+ }
+ firstDataPageOffset = newChunkStart + dictionaryPageSize;
+ dictionaryPageOffset = newChunkStart;
+ } else {
+ firstDataPageOffset = newChunkStart;
+ dictionaryPageOffset = 0;
+ }
+ return new Offsets(firstDataPageOffset, dictionaryPageOffset);
+ }
+
+ private static long readDictionaryPageSize(SeekableInputStream in, long pos)
throws IOException {
+ long origPos = -1;
+ try {
+ origPos = in.getPos();
+ // TODO: Do we need to handle encryption here?
Review comment:
Sounds good. Applying the tools to encrypted files will require a new
design (including management of file identities, that are ingrained in the
encryption process for anti-tampering; pruning a column obviously produces a
new file, that must have a different identity).
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> Invalid data_page_offset
> ------------------------
>
> Key: PARQUET-1977
> URL: https://issues.apache.org/jira/browse/PARQUET-1977
> Project: Parquet
> Issue Type: Bug
> Components: parquet-mr
> Affects Versions: 1.12.0
> Reporter: Gabor Szadovszky
> Assignee: Gabor Szadovszky
> Priority: Major
>
> The thrift field
> [{{data_page_offset}}|https://github.com/gszadovszky/parquet-format/blob/master/src/main/thrift/parquet.thrift#L733]
> is filled with incorrect value. Currently, it always points to the beginning
> of the column chunk which is not correct according to the spec in case there
> is a dictionary page. This is not a regression as it was written incorrectly
> since the beginning of parquet-mr.
> Meanwhile PARQUET-1850 fixed that we never wrote the field
> [{{dictionary_page_offset}}|https://github.com/gszadovszky/parquet-format/blob/master/src/main/thrift/parquet.thrift#L739].
> After the fix we correctly write this field if there is a dictionary filter.
> The problem is we are using the same value to fill both fields. So there are
> two possibilities:
> * There is no dictionary page in the column chunk so {{data_page_offset}} is
> filled with the correct value while {{dictionary_page_offset}} is not filled
> which is still correct. We are good.
> * There is a dictionary page at the beginning of the column chunk so
> {{data_page_offset}} and {{dictionary_page_offset}} are both contains the
> same value. This is not only a regression but it causes issues in other
> implementations (e.g. Impala) where footer validation is more strict than in
> parquet-mr because {{dictionary_page_offset}} shall be less than
> {{data_page_offset}} at all time if it is filled.
> So, we need to fill {{data_page_offset}} correctly.
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