* feat: flags for pushing down new aggregates
* refactor: grouped aggregate rewrite rules
The storage operation ReadGroup aggregates per series on the storage
side. The planner will rewrite grouped aggregate queries to call
ReadGroup, which will perform a partial aggregation, followed by
another operation that will perform the rest of the aggregation on
the compute side.
* feat: storage capabilities for grouped aggregates
* fix: changes from review
* feat: group read operation name should include aggregate
This implements create empty for the window table reader and allows this
table read function to be used when it is specified. It will pass down
the create empty flag from the original window call into the storage
read function.
This also fixes the window table reader so it properly creates
individual tables for each window. Previously, it was constructing one
table for an entire series instead of one table per window.
Tests have been added to verify three edge case behaviors. The first is
the normal read operation where all values are present. The second is
when create empty is specified so null values may be created. The third
is with truncated boundaries to ensure that storage is read from and the
start and stop timestamps get correctly truncated.
Added a (disabled and feature-flagged) planner rule that matches:
ReadRange -> window -> { min, max, mean, count, sum }
The rule requires:
* the pushDownWindowAggregate{Count,Rest} feature flags enabled
* having WindowAggregateCapability
(which StorageReader does not currently have)
* use of "_value" columns only
* window.period == window.every
* window.every.months == 0
* window.every is positive
* window.offset == 0
* standard time columns
* createEmpty is false
The storage filters are modified to use the predicates directly so we do
not have to pass `semantic.FunctionExpression` around. Instead, since
simple expressions are all that are supported anyway, we transform
suitable function expressions into predicates as part of the push down
rule and this simplifies the influxdb reader code.
This also moves the storage predicate conversion code into the standard
library package as it is the only location that uses this code now that
the predicate conversion is done as part of the push down rule.
This refactor was prompted by another refactor of the
`semantic.FunctionExpression` that would cause it to always contain a
`semantic.Block`. Since the push down filter needs the expressions and
to combine them, this refactor allows us not do construct a combined
filter inside of blocks which allows us to have better type safety.
This removes the storage dependency on libflux by moving the interfaces
it implements to the `query` package so it can reference the definitions
rather than the package with the implementation and the registration
with the runtime. This breaks the dependency where a storage package
depends on a flux runtime package.
jlapacik
Jonathan A. Sternberg
Adrian Thurston
Yiqun Zhang