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https://issues.apache.org/jira/browse/HBASE-9870?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13811863#comment-13811863
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Anoop Sam John edited comment on HBASE-9870 at 11/2/13 4:09 AM:
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Yes when we open a HFile, we will use the encoding stored in FileInfo. Down
the line when we read blocks of data there will be the check that you mentioned
in the issue right? That we dont want different encoding scheme for onDisk and
inCache (onDisk != NONE)
In case when we are altering a CF with changing encoding from one alogo to
another this situation arises. My feeling is that is not been handled. So
this situation requires data encoded in a file using one algo should get
encoded using another algo and get stored in cache.
Pls correct me if I am wrong Jimmy.
was (Author: anoop.hbase):
Yes when we open a HFile, we will use the encoding stored in FileInfo. Down
the line when we read blocks of data there will be the check that you mentioned
in the issue right? That we dont want different encoding scheme for onDisk and
inCache (onDisk != NONE)
In case when we are altering a CF with changing encoding from one alogo to
another this situation arises. My feeling is that is not been handled. So
this situation requires data encoded in a file using one algo should get
encoded using another algo and get stored in cache.
> HFileDataBlockEncoderImpl#diskToCacheFormat uses wrong format
> -------------------------------------------------------------
>
> Key: HBASE-9870
> URL: https://issues.apache.org/jira/browse/HBASE-9870
> Project: HBase
> Issue Type: Bug
> Reporter: Jimmy Xiang
>
> In this method, we have
> {code}
> if (block.getBlockType() == BlockType.ENCODED_DATA) {
> if (block.getDataBlockEncodingId() == onDisk.getId()) {
> // The block is already in the desired in-cache encoding.
> return block;
> }
> {code}
> This assumes onDisk encoding is the same as that of inCache. This is not
> true when we change the encoding of a CF. This could be one of the reasons I
> got data loss with online encoding change?
> If I make sure onDisk == inCache all the time, my ITBLL with online encoding
> change worked once for me.
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