Alexander Lapin created IGNITE-17309:
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Summary: Transactional support for partition scans
Key: IGNITE-17309
URL: https://issues.apache.org/jira/browse/IGNITE-17309
Project: Ignite
Issue Type: Improvement
Reporter: Alexander Lapin
It's required to add transactional support to
{code:java}
org.apache.ignite.internal.table.InternalTable#scan {code}
binding it to
{code:java}
org.apache.ignite.internal.storage.MvPartitionStorage#scan(java.util.function.Predicate<org.apache.ignite.internal.schema.BinaryRow>,
java.util.UUID) {code}
along with acquiring corresponding locks, namely S_commit(table) - if a
predicate can produce phantom reads, IS_commit(table) - otherwise.
Besides transactional support itself, it worth to ensure that scans together
with other read commands don't linearized wihtin raft, meaning that raft in
lease-based mode shouldn't perform read-index and thus properly perform
multiple scans concurrently. If given assumption occurred to be incorrect it'll
be required to re-implement scans in order to use storage directly without any
raft interaction. It's possible because any RW-reads goes through
PrimaryReplica that is guaranteed to be up-to-date. The only non-trivial moment
here, is that according to raft paper storage itself isn't guaranteed to apply
all commands up to commit index in a synchronous way, meaning that it's
required to await for applyIndex to be greater or equal than commitIndex.
IGNITE-16907 will introduce storage specific applied index, so that we should
only extract commit index to replica somehow.
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