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https://issues.apache.org/jira/browse/HBASE-3787?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13567864#comment-13567864
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Andrew Purtell edited comment on HBASE-3787 at 1/31/13 5:50 PM:
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I think the above comments all taken together are a reasonable thing to try:
- Introduce a nonce (generated internally by the client) on non-idempotent
operations to convert them into idempotent ones.
- nonce = hash(client address, table, row, timestamp)
- HBaseClient should generate a new nonce whenever a new op is sent to new
server. Reuse the nonce for any retry.
- Server tracks nonces by (client address, nonce, timestamp)
- Add the entry when op processing starts, remove it when finished or failed,
refuse to process an op twice by sending back a DoNotRetryException. Perhaps we
introduce a new exception type like OperationInProgressException which inherits
from DoNotRetryException so the client understands the retry operation was
failed because the previous attempt is still pending server side.
- We should append the nonce to the WALEdit, and recover them along with the
entry data.
was (Author: apurtell):
I think the above comments all taken together are a reasonable thing to try:
- Introduce a nonce (generated internally by the client) on non-idempotent
operations to convert them into idempotent ones.
- nonce = hash(client address, table, row, timestamp)
- HBaseClient should generate a new nonce whenever a request is sent to new
server.
- Server tracks nonces by (client address, nonce, timestamp)
- Add the entry when op processing starts, remove it when finished or failed,
refuse to process an op twice by sending back a DoNotRetryException. Perhaps we
introduce a new exception type like OperationInProgressException which inherits
from DoNotRetryException so the client understands the retry operation was
failed because the previous attempt is still pending server side.
- We should append the nonce to the WALEdit, and recover them along with the
entry data.
> Increment is non-idempotent but client retries RPC
> --------------------------------------------------
>
> Key: HBASE-3787
> URL: https://issues.apache.org/jira/browse/HBASE-3787
> Project: HBase
> Issue Type: Bug
> Components: Client
> Affects Versions: 0.96.0, 0.94.4
> Reporter: dhruba borthakur
> Priority: Critical
> Fix For: 0.96.0
>
>
> The HTable.increment() operation is non-idempotent. The client retries the
> increment RPC a few times (as specified by configuration) before throwing an
> error to the application. This makes it possible that the same increment call
> be applied twice at the server.
> For increment operations, is it better to use
> HConnectionManager.getRegionServerWithoutRetries()? Another option would be
> to enhance the IPC module to make the RPC server correctly identify if the
> RPC is a retry attempt and handle accordingly.
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