[jira] [Updated] (HBASE-15557) document SyncTable in ref guide

["Sean Busbey (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-15557?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sean Busbey updated HBASE-15557:
--------------------------------
    Status: Patch Available  (was: Open)

moved to patch available so I can check out the rendered version. Thanks [~wchevreuil]!

> document SyncTable in ref guide
> -------------------------------
>
>                 Key: HBASE-15557
>                 URL: https://issues.apache.org/jira/browse/HBASE-15557
>             Project: HBase
>          Issue Type: Bug
>          Components: documentation
>    Affects Versions: 1.2.0
>            Reporter: Sean Busbey
>            Assignee: Wellington Chevreuil
>            Priority: Critical
>         Attachments: HBASE-15557.master.001.patch
>
>
> The docs for SyncTable are insufficient. Brief description from [~davelatham] HBASE-13639 comment:
> {quote}
> Sorry for the lack of better documentation, Abhishek Soni. Thanks for bringing it up. I'll try to provide a better explanation. You may have already seen it, but if not, the design doc linked in the description above may also give you some better clues as to how it should be used.
> Briefly, the feature is intended to start with a pair of tables in remote clusters that are already substantially similar and make them identical by comparing hashes of the data and copying only the diffs instead of having to copy the entire table. So it is targeted at a very specific use case (with some work it could generalize to cover things like CopyTable and VerifyRepliaction but it's not there yet). To use it, you choose one table to be the "source", and the other table is the "target". After the process is complete the target table should end up being identical to the source table.
> In the source table's cluster, run org.apache.hadoop.hbase.mapreduce.HashTable and pass it the name of the source table and an output directory in HDFS. HashTable will scan the source table, break the data up into row key ranges (default of 8kB per range) and produce a hash of the data for each range.
> Make the hashes available to the target cluster - I'd recommend using DistCp to copy it across.
> In the target table's cluster, run org.apache.hadoop.hbase.mapreduce.SyncTable and pass it the directory where you put the hashes, and the names of the source and destination tables. You will likely also need to specify the source table's ZK quorum via the --sourcezkcluster option. SyncTable will then read the hash information, and compute the hashes of the same row ranges for the target table. For any row range where the hash fails to match, it will open a remote scanner to the source table, read the data for that range, and do Puts and Deletes to the target table to update it to match the source.
> I hope that clarifies it a bit. Let me know if you need a hand. If anyone wants to work on getting some documentation into the book, I can try to write some more but would love a hand on turning it into an actual book patch.
> {quote}



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