Along with modifying ExecutionContext to be a context and have the
TaskManager return the context itself, this also creates a Monitor
interface and exposes the Monitor through the Context. This way, we can
access the monitor from within the query.Select method and keep all of
the limits inside of the query package instead of leaking them into the
statement executor.
An eventual goal is to remove the InterruptCh from the IteratorOptions
and use the Context instead, but for now, we'll just assign the done
channel from the Context to the IteratorOptions so at least they refer
to the same channel.
* Introduces EXPLAIN ANALYZE command, which
produces a detailed tree of operations used to
execute the query.
introduce context.Context to APIs
metrics package
* create groups of named measurements
* safe for concurrent access
tracing package
EXPLAIN ANALYZE implementation for OSS
Serialize EXPLAIN ANALYZE traces from remote nodes
use context.Background for tests
group with other stdlib packages
additional documentation and remove unused API
use influxdb/pkg/testing/assert
remove testify reference
This allows the query:
SELECT mean(value) FROM cpu GROUP BY time(1d)
To function in some way that makes sense. The upper limit is implicitly
the `now()` starting time and the lower limit will be whichever interval
the lowest point falls into.
When no lower bound is specified and `max-select-buckets` is specified,
the query will only consider points that would satisfy
`max-select-buckets`. So if you have one point written in 1970, have
another point within the last minute, and then do the above query with
`max-select-buckets` being equal to 10, the older point from 1970 will
not be considered.
Originally, casting was performed inside of the query engine especially
for call iterators. Currently, the engine takes care of all casting so
we just need to normalize the iterators types for type safety reasons
rather than actual functional reasons.
Removing this code. Cover coverage showed that it was not hit when run
against the actual server. I ran the tests package and got code coverage
of the query package while running the tests in that package.
This change provides a clear separation between the query engine
mechanics and the query language so that the language can be parsed and
dealt with separate from the query engine itself.