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https://issues.apache.org/jira/browse/HBASE-15085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15091590#comment-15091590
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Victor Xu commented on HBASE-15085:
-----------------------------------
Good question. Actually, there are some scenarios where we had different
encoding configurations between table DATA_BLOCK_ENCODING and HFile loaded. For
example, we sometimes need to migrate HFiles from a table with DIFF encoding to
a NONE encoding table in another cluster. Thus, I think HFile should be
self-descriptive and everyone can bulk load and read the HFile freely as long
as the file version is compatible. Besides, there's another very common
situation: while the HTable descriptor is defined by the DBAs or Devs that know
how to optimize the HBase cluster, the HFiles are usually generated by
application clients who know little about DATA_BLOCK_ENCODING(and some other
parameters) on HTable, and the clients usually use one single
configuration(DIFF) for all different scenarios(some are DIFF tables, and
others are NONE tables).
> IllegalStateException was thrown when scanning on bulkloaded HFiles
> -------------------------------------------------------------------
>
> Key: HBASE-15085
> URL: https://issues.apache.org/jira/browse/HBASE-15085
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.98.12, 1.1.2
> Environment: HBase-0.98.12 & Hadoop-2.6.0 & JDK1.7
> HBase-1.1.2 & Hadoop-2.6.0 & JDK1.7
> Reporter: Victor Xu
> Assignee: Victor Xu
> Labels: hfile
> Attachments: HBASE-15085-0.98-v1.patch, HBASE-15085-0.98-v2.patch,
> HBASE-15085-0.98-v3.patch, HBASE-15085-0.98-v4.patch, HBASE-15085-v1.patch,
> HBASE-15085-v2.patch, HBASE-15085-v3.patch, HBASE-15085-v4.patch
>
>
> IllegalStateException was thrown when we scanned from an HFile which was bulk
> loaded several minutes ago, as shown below:
> {code}
> 2015-12-16 22:20:54,456 ERROR
> com.taobao.kart.coprocessor.server.KartCoprocessor:
> icbu_ae_ws_product,/0055,1450275490479.6a6a700f465ad074287fed720c950f7c.
> batchNotify exception
> java.lang.IllegalStateException: EncodedScanner works only on encoded data
> blocks
> at
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2$EncodedScannerV2.updateCurrentBlock(HFileReaderV2.java:1042)
> at
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2$EncodedScannerV2.seekTo(HFileReaderV2.java:1093)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.seekAtOrAfter(StoreFileScanner.java:244)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.seek(StoreFileScanner.java:152)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.seekScanners(StoreScanner.java:329)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.<init>(StoreScanner.java:188)
> at
> org.apache.hadoop.hbase.regionserver.HStore.getScanner(HStore.java:1879)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.<init>(HRegion.java:4068)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.instantiateRegionScanner(HRegion.java:2029)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:2015)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:1992)
> {code}
> I used 'hbase hfile' command to analyse the meta and block info of the hfile,
> finding that even through the DATA_BLOCK_ENCODING was 'DIFF' in FileInfo, the
> actual data blocks was written without any encoding algorithms(BlockType was
> 'DATA', not 'ENCODED_DATA'):
> {code}
> Fileinfo:
> BLOOM_FILTER_TYPE = ROW
> BULKLOAD_SOURCE_TASK = attempt_1442077249005_606706_r_000012_0
> BULKLOAD_TIMESTAMP = \x00\x00\x01R\x12$\x13\x12
> DATA_BLOCK_ENCODING = DIFF
> ...
> DataBlock Header:
> HFileBlock [ fileOffset=0 headerSize()=33 blockType=DATA
> onDiskSizeWithoutHeader=65591 uncompressedSizeWithoutHeader=65571
> prevBlockOffset=-1 isUseHBaseChecksum()=true checksumType=CRC32
> bytesPerChecksum=16384 onDiskDataSizeWithHeader=65604
> getOnDiskSizeWithHeader()=65624 totalChecksumBytes()=20 isUnpacked()=true
> buf=[ java.nio.HeapByteBuffer[pos=0 lim=65624 cap=65657],
> array().length=65657, arrayOffset()=0 ]
> dataBeginsWith=\x00\x00\x003\x00\x00\x00\x0A\x00\x10/0008:1000000008\x01dprod
> fileContext=HFileContext [ usesHBaseChecksum=true checksumType=CRC32
> bytesPerChecksum=16384 blocksize=65536 encoding=NONE includesMvcc=true
> includesTags=false compressAlgo=NONE compressTags=false cryptoContext=[
> cipher=NONE keyHash=NONE ] ] ]
> {code}
> The data block encoding in file info was not consistent with the one in data
> block, which means there must be something wrong with the bulkload process.
> After debugging on each step of bulkload, I found that LoadIncrementalHFiles
> had a bug when loading hfile into a splitted region.
> {code}
> /**
> * Copy half of an HFile into a new HFile.
> */
> private static void copyHFileHalf(
> Configuration conf, Path inFile, Path outFile, Reference reference,
> HColumnDescriptor familyDescriptor)
> throws IOException {
> FileSystem fs = inFile.getFileSystem(conf);
> CacheConfig cacheConf = new CacheConfig(conf);
> HalfStoreFileReader halfReader = null;
> StoreFile.Writer halfWriter = null;
> try {
> halfReader = new HalfStoreFileReader(fs, inFile, cacheConf, reference,
> conf);
> Map<byte[], byte[]> fileInfo = halfReader.loadFileInfo();
> int blocksize = familyDescriptor.getBlocksize();
> Algorithm compression = familyDescriptor.getCompression();
> BloomType bloomFilterType = familyDescriptor.getBloomFilterType();
> // use CF's DATA_BLOCK_ENCODING to initialize HFile writer
> HFileContext hFileContext = new HFileContextBuilder()
> .withCompression(compression)
>
> .withChecksumType(HStore.getChecksumType(conf))
>
> .withBytesPerCheckSum(HStore.getBytesPerChecksum(conf))
> .withBlockSize(blocksize)
>
> .withDataBlockEncoding(familyDescriptor.getDataBlockEncoding())
> .build();
> halfWriter = new StoreFile.WriterBuilder(conf, cacheConf,
> fs)
> .withFilePath(outFile)
> .withBloomType(bloomFilterType)
> .withFileContext(hFileContext)
> .build();
> HFileScanner scanner = halfReader.getScanner(false, false, false);
> scanner.seekTo();
> do {
> KeyValue kv = KeyValueUtil.ensureKeyValue(scanner.getKeyValue());
> halfWriter.append(kv);
> } while (scanner.next());
> // force encoding setting with the original HFile's file info
> for (Map.Entry<byte[],byte[]> entry : fileInfo.entrySet()) {
> if (shouldCopyHFileMetaKey(entry.getKey())) {
> halfWriter.appendFileInfo(entry.getKey(), entry.getValue());
> }
> }
> } finally {
> if (halfWriter != null) halfWriter.close();
> if (halfReader != null)
> halfReader.close(cacheConf.shouldEvictOnClose());
> }
> }
> {code}
> As shown above, when an HFile which has a DIFF encoding is bulkloaded into a
> splitted region whose CF's DATA_BLOCK_ENCODING is NONE, the two new HFiles
> would have inconsistent encodings.
> Besides, it would be OK if splitting region's DATA_BLOCK_ENCODING is DIFF and
> bulk loaded HFile has NONE, because the initial bulkloaded HFile would not
> write the encoding info into its meta (NoOpDataBlockEncoder.saveMetadata() is
> empty), and It then would not rewrite encoding in two generated Files in
> copyHFileHalf(). Two new HFiles' meta info would be consistent with their
> block headers, which would all be DIFF. So, no Exception would be thrown when
> scanning these files.
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