ggershinsky commented on a change in pull request #925:
URL: https://github.com/apache/parquet-mr/pull/925#discussion_r700210573
##########
File path:
parquet-hadoop/src/main/java/org/apache/parquet/format/converter/ParquetMetadataConverter.java
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@@ -1254,14 +1276,41 @@ static FileMetaData
filterFileMetaDataByMidpoint(FileMetaData metaData, RangeMet
return metaData;
}
+ private static long tryUseFileOffset(RowGroup rowGroup, long preStartIndex,
long preCompressedSize) {
+ long startIndex = 0;
+ startIndex = rowGroup.getFile_offset();
+ // skip checking the first rowGroup
+ // (in case of summary file, there are multiple first groups from
different footers)
+ if (preStartIndex != 0 && preStartIndex <= startIndex) {
+
+ //calculate start index for other blocks
+ long minStartIndex = preStartIndex + preCompressedSize;
+ if (startIndex < minStartIndex) {
+ // a bad offset detected, try first column's offset
+ // can not use minStartIndex in case of padding
+ startIndex = getOffset(rowGroup.getColumns().get(0));
Review comment:
that might work for range filtering. as for the explicit offset
filtering, the precision might be important. In systems that [use
padding](https://github.com/apache/parquet-mr/blob/master/parquet-hadoop/src/main/java/org/apache/parquet/hadoop/util/HadoopOutputFile.java#L37)
(HDFS, WEBHDFS, VIEWFS) - instead of `startIndex = minStartIndex` , we might
have to throw an exception when this is called from
`filterFileMetaDataByStart` saying that this file can't be split by offsets,
and should be processed without splitting. Again, given the number of
conditions for this situation to occur, and the fact that 1.12.0 is not
released yet any framework, such exceptions might never be thrown in reality.
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