If no chunking was requested by the user, the co-ordinating node buffers all
results in RAM before emitting a single result. However buffering was not
merging results for rows which had data for the same series. This change fixes this.
Fixes issue #3242.
Any literal values in a math query e.g. the '2' in 'value * 2' are
stored as float64, so all other values must be cast to this type. This
does mean that precision may be lost if the integer values are greater
than 2^53.
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.
Cory LaNou
Philip O'Toole
Ben Johnson