Xuesen Liang created HBASE-29217:
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Summary: Enhancement for CheckAndMutate
Key: HBASE-29217
URL: https://issues.apache.org/jira/browse/HBASE-29217
Project: HBase
Issue Type: Improvement
Components: Client, regionserver
Reporter: Xuesen Liang
Assignee: Xuesen Liang
The current implementation of _CheckAndMutate_ operation provides two
conditional verification modes:
1. Column Non-exists:
{code:java}
ifMatches(family, qualifier, CompareOperator.EQUAL, null)
{code}
Validates that the specified column does not exist.
2. Column Value Comparison/Filter
{code:java}
ifMatches(family, qualifier, CompareOperator, value)
{code}
OR
{code:java}
ifMatches(Filter)
{code}
Verifies that the column exists and satisfies the defined comparison/filter
logic.
*Limitation:*
The existing API lacks support for composite conditional checks of the form:
_"Column X either does not exist, OR exists and meets comparison condition"._
*Current Workaround & Risks:*
To implement this logic, developers must:
{code:java}
// Step 1: Check column absence
checkAndMutate.ifMatches(family, qualifier, CompareOperator.EQUAL, null)
// Step 2: Check value condition if Step 1 fails
checkAndMutate.ifMatches(family, qualifier, CompareOperator, value)
{code}
This approach introduces following critical issues:
* Non-atomic Execution: The two-phase check creates race conditions.
* API Complexity: Forces developers to implement client-side synchronization
logic.
* Performance: There are two RPC calls.
*Proposed Solution:*
Introduce a composite conditional operator:
{code:java}
ifNotExistsOr(family, qualifier, CompareOperator, value)
{code}
*Implementation Benefits:*
* Atomic Guarantee: Executes the "NOT EXISTS OR SATISFIES" logic in a single
RPC call.
* API Simplification: Reduces client-side code complexity.
This enhancement would align HBase's conditional mutation capabilities with
modern database systems supporting compound atomic predicates, while
maintaining backward compatibility.
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