Previously batch statement result set included rows for only
those updates which have a prefetch data present (i.e. there
was an "old" (pre-existing) row for a key).
Also, these rows were sorted not in the order in which statements
appear in the batch, but in the order of updated clustering keys.
If we have a batch which updates a few non-existent keys, then
it's impossible to figure out which update inserted a new key
by looking at the query response. Not only because the responses
may not correspond to the order of statements in the batch, but
even some rows may not show up in the result set at all.
The patch proposes the following fix:
For conditional batch statements the result set now always
includes a row for each LWT statement, in the same order
in which individual statements appear in the batch.
This way we can always tell which update did actually insert
a new key or update the existing one.
`update_parameters::prefetch_data::row::is_in_cas_result_set`
member variable was removed as well as supporting code in
`cas_request::applies_to` which iterated through cas updates
and marked individual `prefetch_data` rows as "need to be in
cas result set".
Instead now `cas_request::applies_to` is significantly
simplified since it doesn't do anything more than checking
`stmt.applies_to()` in short-circuiting manner.
A few tests for the issue are written, other lwt-batch-related
tests were adjusted accordingly to include rows in result set
for each statement inside conditional batches.
Tests: unit(dev, debug)
Co-authored-by: Konstantin Osipov <kostja@scylladb.com>
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Add a couple of cql tests regarding conditional batches:
1. Verify that "delete" takes priority over "insert"
when applied to the same row within the same batch.
2. Test that a workaround for the issue works as expected (i.e.
delete only individual cells instead of the full record).
Tests: unit(dev)
Fixes: #6273
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Message-Id: <20200506201200.176590-1-pa.solodovnikov@scylladb.com>
These unit tests cover all CQL aspects of lightweight transactions,
such as grammar, null semantics, batch semantics, result set
format, and so on.
For now, comment out unicode tests: test output depends
on libjsoncpp version in use.
