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https://issues.apache.org/jira/browse/IGNITE-19228?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Roman Puchkovskiy reassigned IGNITE-19228:
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Assignee: Roman Puchkovskiy
> Schema validation during tx processing: common framework
> --------------------------------------------------------
>
> Key: IGNITE-19228
> URL: https://issues.apache.org/jira/browse/IGNITE-19228
> Project: Ignite
> Issue Type: Improvement
> Reporter: Roman Puchkovskiy
> Assignee: Roman Puchkovskiy
> Priority: Major
> Labels: ignite-3
>
> h3. Definitions
> When a coordinator initiates a transaction, it takes a timestamp
> beginTs=Ts=Now and sends it to all participants. On first access to a table Q
> (in this transaction) on a primary replica node, the schema of Q is obtained
> for moment Ts; this schema is called ‘initial schema’ and associated with
> this transaction on this node. When a commit of the transaction is processed
> with commit timestamp Tc, the node obtains the schema of Q again, now at the
> moment of Tc; this is the ‘commit schema’. If the commit schema is different
> from the initial schema and not compatible with it (using the notion of the
> forward compatibility defined below), the commit fails (and the transaction
> is aborted).
> An initial schema is said to be _forward-compatible_ with a commit schema if,
> having a tuple written with the initial schema, it is enough to know the
> commit schema to read the tuple.
> An initial schema is said to be _backward-compatible_ with a commit schema if
> the same is true the other way around: having a tuple written with the commit
> schema, we can read it having just the initial schema.
> h3. What to do
> We need to validate:
> * forward schema compatibility on commit
> * backward compatibility on reads in RW txs
> If a schema change is incompatible, the transaction is aborted.
> This task is about the implementation of a common framework allowing to do
> validations with just a single validator that considers all schema changes
> incompatible, and using this framework while processing transactions.
> Real validators will be added in a follow-up task.
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