Andrey N. Gura created IGNITE-14269:
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Summary: Design conditional multi update functionality for meta storage client
Key: IGNITE-14269
URL:
https://issues.apache.org/jira/browse/IGNITE-14269 Project: Ignite
Issue Type: New Feature
Reporter: Andrey N. Gura
Assignee: Andrey N. Gura
Fix For: 3.0.0-alpha2
Define entities required for implementation of conditional multi updates (aka "transactions") for meta storage.
Requirements:
- Design should provide possibility to define conditional updates in if-then-else manner with nested branches.
- Update always starts with condition.
- Any nested branch must start with condition.
- Update can't precede to condition.
- Every branch can yield exactly one custom result (limited by number of simple types) and any number of entries. Corresponding expression always must be at the end of branch.
- Condition for entry revision allows the following comparisons: equal, !equal, less, greater.
- Condition for entry value allows the following operations (byte-wise): equal, !equal.
- Update allows the following operations: put, remove, no-op.
- Condition can not use previously defined condition instance again because it will lead to graph cycle and infinite update execution.
Assumptions:
- It seems that conditions and updates entities can be conveniently linked using chaining.
Simple example (pseudocode):
{code}
CompletableFuture<Result, List<Entry>> = invoke(valCond(EQUAL, perstEnabled, true)._then(
valCond(EQUAL, walEnabled, true)._then(
update(walEnabled, true)).
_else(
update(walEnabled, false))
)._else(NoopUpdate))
{code}
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