The vector store returns for every ANN search, in addition to the keys
of the matching items, two additional vectors - "distances" and
"similarity_cores". The "distances" are raw distance metrics - lower
scores are better matches, while "similarity_scores" are modified
such that higher scores are better matches.
Traditionally, search scores in systems like Cassandra and Open Search
use the "similarity scores" approach (higher is better, results are
returned in decreasing similarity order), so this is the more interesting
vector of the two.
But before this patch, our vector_store_client::ann() inspected
only "distances". But... then, it didn't return even that to the
caller :-)
So in this patch, we:
1. Ignore "distances" and instead look at "similarity scores",
which is what users really want based on their experience with
other vector and non-vector search engines.
2. Return the similarity score of each match together with the match.
We already have this score (the vector store returns it) and we
can add it to the existing primary_key structure of each result.
So each result is a "struct primary_key" which has fields partition,
clustering, and after this patch - similarity.
Existing callers in CQL and Alternator vector search will ignore this
"similarity" field in each result, and not notice it was added.
But in the next patch, we'll allow Alternator's vector search to
return this similarity in each result.
The existing unit tests for vector_store_client.cc mocked vector-store
responses with "distances", without "similarity_scores", so no longer
represent what we actually expect the vector store to do. So this patch
also contains modifications for these tests, to mock and to test
"similarity_scores" - not "distances". The more interesting tests, in
the next patch, use the real vector store and check that we really do
get a "similarity_scores" response from it.
This patch also handles a small corner case for DOT_PRODUCT, which is
the only unbounded similarity function. If the similarity overflows
the 32-bit float, the vector store returns a JSON "null" instead of
a JSON number (since JSON doesn't support infinite numbers). Our
existing vector-store client code errored out when it saw this "null",
which is wrong - the request should be allowed to proceed. So in this
patch when we see a "null" JSON for similarity, we return +Inf.
This is usually correct because the top results really have +Inf, not
-Inf, but if we ask for all items we can reach those with similarity
-Inf and incorrectly assign +Inf to them (we have a test for this case
in the next patch). But this problenm won't happen when Limit is low,
and in any case it's better than aborting the request after it had
already succeeded.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
When a `with_connect` operation timed out, the underlying connection
attempt continued to run in the reactor. This could lead to a crash
if the connection was established/rejected after the client object had
already been destroyed. This issue was observed during the teardown
phase of a upcoming high-availability test case.
This commit fixes the race condition by ensuring the connection attempt
is properly canceled on timeout.
Additionally, the explicit TLS handshake previously forced during the
connection is now deferred to the first I/O operation, which is the
default and preferred behavior.
Fixes: SCYLLADB-832
The connection timeout was 2 minutes and the keep-alive
timeout was 11 minutes. If a vector store node became unreachable, these
long timeouts caused significant delays before the system could recover,
negatively impacting high availability.
This change aligns both timeouts with the `request_timeout`
configuration, which defaults to 10 seconds. This allows for much
faster failure detection and recovery, ensuring that unresponsive nodes
are failed over from more quickly.
This commit introduces TLS encryption support for vector store connections.
A new configuration option is added:
- vector_store_encryption_options.truststore: path to the trust store file
To enable secure connections, use the https:// scheme in the
vector_store_primary_uri/vector_store_secondary_uri configuration options.
Fixes: VECTOR-327
The `abort_source_timeout` and `repeat_until` functions are moved to
the shared utility header `test/vector_search/utils.hh`.
This allows them to be reused by upcoming `client` unit tests, avoiding
code duplication.
