This is a CQL-based Cassandra storage component, built upon the Zipkin v1 thrift model. This uses Cassandra 2.2+ features, but is tested against the latest patch of Cassandra 3.11.
CassandraSpanStore.getDependencies() returns pre-aggregated dependency links (ex via zipkin-dependencies).
The implementation uses the Datastax Java Driver 3.x.
zipkin2.storage.cassandra.v1.CassandraStorage.Builder includes defaults that will
operate against a local Cassandra installation.
Queries are logged to the category "com.datastax.driver.core.QueryLogger" when debug or trace is enabled via SLF4J. Trace level includes bound values.
See Logging Query Latencies for more details.
This module conditionally runs integration tests against a local Cassandra instance.
Tests are configured to automatically access Cassandra started with its defaults.
To ensure tests execute, download a Cassandra 2.2+ distribution, extract it, and run bin/cassandra.
If you run tests via Maven or otherwise when Cassandra is not running, you'll notice tests are silently skipped.
Results :
Tests run: 62, Failures: 0, Errors: 0, Skipped: 48
This behaviour is intentional: We don't want to burden developers with installing and running all storage options to test unrelated change. That said, all integration tests run on pull request via Travis.
This component is tuned to help reduce the size of indexes needed to perform query operations. The most important aspects are described below. See CassandraStorage for details.
Redundant requests to store autocomplete values are ignored for an hour to reduce load. This is implemented by DelayLimiter
Indexing of traces are optimized by default. This reduces writes to Cassandra at the cost of memory needed to cache state. This cache is tunable based on your typical span count.
Core annotations,
ex "sr", are not written to annotations_index, as they aren't intended for use in user queries.
Also, binary annotation values longer than 256 characters are not indexed. These optimizations
significantly limit writes per trace.
User-supplied query limits are over-fetched according to a configured index fetch multiplier in attempts to mitigate redundant data returned from index queries.
While not supported, here are some notes if you are running the original schema on Cassandra 2.1.
The zipkin-ui always specifies a service name, but the http api permits leaving it out. This won't work in Cassandra 2.1
Upgrades assume features that are present in Cassandra 2.2+. Do not have zipkin upgrade your schema if you are running Cassandra 2.1.
If using zipkin-server, set CASSANDRA_ENSURE_SCHEMA=false.
Manually running below will add default ttls to the original schema.
ALTER TABLE zipkin.traces WITH default_time_to_live = 604800;
ALTER TABLE zipkin.service_span_name_index WITH default_time_to_live = 259200;
ALTER TABLE zipkin.service_name_index WITH default_time_to_live = 259200;
ALTER TABLE zipkin.span_names WITH default_time_to_live = 259200;
ALTER TABLE zipkin.annotations_index WITH default_time_to_live = 259200;
ALTER TABLE zipkin.dependencies WITH default_time_to_live = 259200;
ALTER TABLE zipkin.service_names WITH default_time_to_live = 259200;