Roman Puchkovskiy created IGNITE-20108:
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Summary: Use tableEnlistTs as baseTs when validating schema
Key: IGNITE-20108
URL: https://issues.apache.org/jira/browse/IGNITE-20108
Project: Ignite
Issue Type: Improvement
Reporter: Roman Puchkovskiy
Fix For: 3.0.0-beta2
https://cwiki.apache.org/confluence/display/IGNITE/IEP-110%3A+Schema+synchronization%3A+basic+schema+changes#IEP110:Schemasynchronization:basicschemachanges-Basicrequirements
requires an ALTER TABLE occurring after a transaction had started but before
the tx touched the table for the first time to be visible to the tx and not
cause its abortion.
To achieve this, we should take baseTs=tableEnlistTs(tx, table).
Both tx coordinator and primary need to track those tableEnlistTs. On the
coordinator and the primary these values will most likely be different (because
they are taken from different clocks: the coordinator clock and the primary
clock), but this is acceptable.
h3. Coordinator
The coordinator already tracks some information about a transaction (namely,
its enlisted partitions); tableEnlistTs should be added to this structure. When
doing the client schema version check (IGNITE-20106), the coordinator should
check whether tableEnlistTs already exists for the table in question, and, if
not, generate it (as HLC.now()) and remember it; then use it to obtain the
server-side schema version and use the version to validate the client's request.
h3. Primary
The primary should track tableEnlistSchemaVersion too. It should make sure that
the coordinator's tableEnlistSchemaVersion (that can be determined by the
schema version of the tuples that the client sends) matches the primary's
tableEnlistSchemaVersion (that is determined by the operationTs (on the primary
clock) of the first operation touching the table in the transaction.
On recovery, the primary should recover tableEnlistSchemaVersions; it can do so
by scanning all writes made by a transaction and looking into Schema Version
mentioned in the corresponding tuples.
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