[HBASE-9899] for idempotent operation dups, return the result instead of throwing conflict exception

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.3.0, 2.0.0
• Hadoop Flags: Reviewed

Release Note

Non-idempotent operations (increment/append/checkAndPut/...) may throw OperationConflictException even though the increment/append succeeded. For example (client rpc retries number set to 3):

1. first increment rpc request success
2. client timeout and send second rpc request, but nonce is same and save in server. The server found that it has already succeed, so return a OperationConflictException to make sure that increment operation only be applied once in server.

This patch will solve this problem by read the previous result when receive a duplicate rpc request.
1. Store the mvcc to OperationContext. When first rpc request succeed, store the mvcc for this operation nonce.
2. When there are duplicate rpc request, convert to read result by the mvcc.

• Assignee: Guanghao Zhang
• Reporter: Sergey Shelukhin
• Created: 06/Nov/13 00:43
• Updated: 16/Jun/22 18:28
• Resolved: 27/Apr/17 09:12

Description

After HBASE-3787, we could store mvcc in operation context, and use it to convert the modification request into read on dups instead of throwing OperationConflictException.
MVCC tracking will have to be aware of such MVCC numbers present. Given that scanners are usually relatively short-lived, that would prevent low watermark from advancing for quite a bit more time

Issue Links

• is blocked by: HBASE-3787 Increment is non-idempotent but client retries RPC
• is related to: HBASE-24515 batch Increment/Append fails when retrying the RPC
• relates to: HBASE-16801 The Append/Increment may return the data from future