The patch calculates row count during result building and while merging.
If one of results that are being merged does not have row count the
merged result will not have one either.
Query result digest is used to verify that all replicas have the same
data. Therefore, it needs to contain more information than the query
result itself in order to ensure proper detection of disagreements.
Generally, adding clustering keys to the digest regardless of whether
the client asked for them will guarantee correctness. However, adding
tombstones as well improves the chances of early detection of nodes
containing stale data.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
The query result footprint for cassandra-stress mutation as reported
by tests/memory-footprint increased by 18% from 285 B to 337 B.
perf_simple_query shows slight regression in throughput (-8%):
build/release/tests/perf/perf_simple_query -c4 -m1G --partitions 100000
Before: ~433k tps
After: ~400k tps
We want the format of query results to be eventually defined in the
IDL and be independent of the format we use in memory to represent
collections. This change is a step in this direction.
The change decouples format of collection cells in query results from
our in-memory representation. We currently use collection_mutation_view,
after the change we will use CQL binary protocol format. We use that because
it requires less transformations on the coordinator side.
One complication is that some list operations need to retrieve keys
used in list cells, not only values. To satisfy this need, new query
option was added called "collections_as_maps" which will cause lists
and sets to be reinterpreted as maps matching their underlying
representation. This allows the coordinator to generate mutations
referencing existing items in lists.
Allows for having more than one clustering row range set, depending on
PK queried (although right now limited to one - which happens to be exactly
the number of mutiplexing paging needs... What a coincidence...)
Encapsulates the row_ranges member in a query function, and if needed holds
ranges outside the default one in an extra object.
Query result::builder::add_partition now fetches the correct row range for
the partition, and this is the range used in subsequent iteration.
When partition has no live regular rows, but has some data live in the
static row, then it should appear in the results, even though we
didn't select any static column.
To reproduce:
create table cf (k blob, c blob, v blob, s1 blob static, primary key (k, c));
update cf set s1 = 0x01 where k = 0x01;
update cf set s1 = 0x02 where k = 0x02;
select k from cf;
The "select" statement should return 2 rows, but was returning 0.
The following query worked fine, because static columns were included:
select * from cf;
The data query should contain only live data, so we shouldn't write a
partition entry if it's supposed to be absent from the results. We
can'r tell that though until we've processed all the data. To solve
this problem, query result writer is using an optimistic approach,
where the partition header will be retracted from the buffer
(cheaply), if it turns out there's no live data in it.
Deleted cells store deletion time not expiry time. This change makes
expiry() valid only for live cells with TTL and adds deletion_time(),
which is inteded to be used with deleted cells.
