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Clarify doc for readset validations (#2647)
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Clarify that both prior blocks and prior transactions in the same block
are considered during readset validation.

Signed-off-by: David Enyeart <enyeart@us.ibm.com>
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denyeart authored Jun 7, 2021
1 parent a8dbb68 commit 07808a0
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Showing 2 changed files with 10 additions and 8 deletions.
6 changes: 4 additions & 2 deletions docs/source/glossary.rst
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Expand Up @@ -148,8 +148,10 @@ Concurrency Control Version Check

Concurrency Control Version Check is a method of keeping ledger state in sync across
peers on a channel. Peers execute transactions in parallel, and before committing
to the ledger, peers check whether the state read at the time the transaction was executed
has been modified. If the data read for the transaction has changed between execution time and
to the ledger, peers check whether the state read at the time the transaction
was executed has been modified in a new block that was in-flight at time of execution
or in a prior transaction in the same block.
If the data read for the transaction has changed between execution time and
commit time, then a Concurrency Control Version Check violation has
occurred, and the transaction is marked as invalid on the ledger and values
are not updated in the state database.
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12 changes: 6 additions & 6 deletions docs/source/readwrite.rst
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Expand Up @@ -73,12 +73,12 @@ read-write set for updating the versions and the values of the affected
keys.

In the validation phase, a transaction is considered ``valid`` if the
version of each key present in the read set of the transaction matches
the version for the same key in the world state - assuming all the
preceding ``valid`` transactions (including the preceding transactions
in the same block) are committed (*committed-state*). An additional
validation is performed if the read-write set also contains one or more
query-info.
version of each key present in the read set of the transaction (from time of simulation)
matches the current version for the same key, taking into consideration
``valid`` transactions that have been committed to state from new
blocks since the transaction was simulated, as well as valid preceding transactions
in the same block. An additional validation is performed if the read-write set
also contains one or more query-info.

This additional validation should ensure that no key has been
inserted/deleted/updated in the super range (i.e., union of the ranges)
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