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https://issues.apache.org/jira/browse/HBASE-11292?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14020617#comment-14020617
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Jeffrey Zhong commented on HBASE-11292:
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{quote}
since the client would have to perform a read to find the previous value prior
to the delete, then issue a new put, instead of simply issuing an undelete with
the same parameters as the prior delete.
{quote}
I think there is no difference in terms of the read because you need to read
the previous "delete" put as well to construct the "undelete" put while the
other way need to read&write more data.
> Add an "undelete" operation
> ---------------------------
>
> Key: HBASE-11292
> URL: https://issues.apache.org/jira/browse/HBASE-11292
> Project: HBase
> Issue Type: New Feature
> Components: Deletes
> Reporter: Gary Helmling
> Labels: Phoenix
>
> While column families can be configured to keep deleted cells (allowing time
> range queries to still retrieve those cells), deletes are still somewhat
> unique in that they are irreversible operations. Once a delete has been
> issued on a cell, the only way to "undelete" it is to rewrite the data with a
> timestamp newer than the delete.
> The idea here is to add an "undelete" operation, that would make it possible
> to cancel a previous delete. An undelete operation will be similar to a
> delete, in that it will be written as a marker ("tombstone" doesn't seem like
> the right word). The undelete marker, however, will sort prior to a delete
> marker, canceling the effect of any following delete.
> In the absence of a column family configured to KEEP_DELETED_CELLS, we can't
> be sure if a prior delete marker and the effected cells have already been
> garbage collected. In this case (column family not configured with
> KEEP_DELETED_CELLS) it may be necessary for the server to reject undelete
> operations to avoid creating the appearance of a client contact for undeletes
> that can't reliably be honored.
> I think there are additional subtleties of the implementation to be worked
> out, but I'm also interested in a broader discussion of interest in this
> capability.
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