This commit refactors the tsdb query engine to use separate aggregate
and raw execution paths, encapsulates cursor functionality, and removes
the TagSetCursor from the aggregate path. By removing the TagSetCursor,
we can pass sets of unordered values to the map functions and bypass
the `container/heap` entirely.
For aggregate queries, having a null result means that you haven't
got any data for that time period. CQs used this as a signal that
the measurement was not created and dropped the entire write.
INTO queries can have any structure, including wildcards, so dropping
the entire query isn't going to work. Instead, just drop the nulls
returned.
Since INTO queries need to have absolute information about the database
to work, we need to create a loopback interface back to the cluster
in order to perform them.
This change adds support for diagnostics by decomposing the existing
interface into two interfaces -- one for stats, and the other for
diags. It also adds some basic monitor of system, network, and the Go
runtime.
This change significantly simplifies query executor code. Before this
change there were two types of executors -- RawExecutor and
AggregateExecutor. These two types only differed in one function
Execute(). Otherwise all other methods on the Executors were common and
duplicated between executors
This change merges the two executors into a single type called, wait for
it, Executor and simply switches execute functions depending on the
statement type.
The multiple checks for Mapper and Executor type -- the lack of DRYness
in this code -- meant the same checks would need to be copied. Therefore
this change, as well as fixing the bug, improves the situation a little
bit by *asking* the Mappers what type of Executor is required. This code
is still not ideal.
Fixes#3355.
With this change, the query engine code gathers information about
shards and tagsets by working with individual shards, collating the
information, and returning that to the client. It does not assume that any
particular shard is local, and accesses all shards through abstracted
Mappers, of which there are two types -- a Mapper type for Raw queries
and a second type for Aggregate queries. There are corresponding
Executors for each type of Mapper, but both types of Executors share the
same interface.
Ben Johnson
Paul Dix
Cory LaNou
David Norton
ch33hau
Jason Wilder
Daniel Morsing
Daniel Morsing
Philip O'Toole
Philip O'Toole
gunnaraasen
Alexander Morozov
Joseph Crail