`SHOW TAG VALUES` output has been modified to print the measurement name
for every measurement and to return the output in two columns: key and
value. An example output might be:
> SHOW TAG VALUES WITH KEY IN (host, region)
name: cpu
---------
key value
host server01
region useast
name: mem
---------
key value
host server02
region useast
`measurementsByExpr` has been taught how to handle reserved keys (ones
with an underscore at the beginning) to allow reusing that function and
skipping over expressions that don't matter to the call.
Fixes#5593.
Previously the call iterator would normalize the time to the interval
for all calls. This meant that when `first()` or `last()` was called
with no group by interval the value would be found for each shard, the
time was normalized, then it tried to find the value between the shards
(but no longer with any time data as that had already been eliminated).
This removes part of the time logic from the call iterators and makes a
new iterator `IntervalIterator` to normalize the times as they come out
of the underlying iterator.
Fixes#5890.
All three of these iterators are supposed to support all four types of
iterators, but the implementation was never done for string or boolean.
Fixes#5886.
This refactor is primarily to support Kapacitor. Kapacitor doesn't care
about the iterators and mostly keeps the points it handles in memory.
The iterator interface is more than Kapacitor cares about.
This commit refactors and opens up the internals of aggregating and
reducing incoming points so it can be used by an outside library with
the same code. It also makes the iterators used by the call iterators
publically usable with new functionality.
Reducers are split into two methods which are separate interfaces that
can be combined for dealing with casting between different types. The
Aggregator interfaces accept points into the aggregator and retain any
internal state they need. The Emitter interface will then create a point
from that aggregated state which can be fed to the iterator. The
Emitters do not fill in the name or tag of the point as that is expected
to be done by the person aggregating the point. While the Emitters do
sometimes fill in the time, that value will also be overwritten by the
iterator. Filling in the time is to allow a future version that will
allow returning the point time instead of just the interval time.
The limit iterator would short circuit if there were no dimensions and
all points had been read. It also needs to consider that multiple
sources will require reading the entire iterator too, so the short
circuit requires only a single source.
Fixes#5871.
The RPC handler for remote queries would attempt to reuse a closed
connection for certain commands that didn't use pooling. The RPC
commands that close the connection have been fixed to not try reusing
the connection.
When creating an iterator, if there are no points to return, the points
decoder would hit an EOF that it didn't catch and would return that
error back to the client who made the request. It now properly returns
no points by using a `nilFloatIterator` if there are no points to
return.
This fixes remote execution when a cluster has nothing to return.
The dimensions array in `RewriteWildcards` gets emptied by an earlier
section of the code and then tries to iterate over that empty slice to
append it to the list of dimensions.
That makes the loop dead code that can't ever be hit.
Also improve the efficiency of this method by not creating a new slice
when there are no wildcards. We already check at the beginning of the
function if there is a wildcard out of necessity. There's no point in
making a new slice and copying the contents if we know that there will
be no wildcards to expand.
It also improves memory efficiency by assuming that if a wildcard
exists, there is only one and the pre-allocated slice can take advantage
of that. If there are multiple wildcards, then a new slice will have to
be created in the middle of the loop to raise the capacity.
When a wildcard is specified for the field but not the dimensions, the
dimensions get added to the list of fields as part of
`RewriteWildcards()`.
But when a dimension was given with no wildcard, the dimension didn't
get removed from the wildcard in the fields section. This teaches the
rewriter to disclude dimensions explicitly included from being expanded
as a field. Now this statement when a measurement has one tag named host
and a field named value:
SELECT * FROM cpu GROUP BY host
Would expand to this:
SELECT value FROM cpu GROUP BY host
Instead of this:
SELECT host, value FROM cpu GROUP BY host
If you want the latter behavior, you can include it like this:
SELECT host, * FROM cpu GROUP BY host
Fixes#5770.
The name of the column will be every measurement located inside of the
math expression in the order they are encountered in within the
expression.
Also handle `*influxql.ParenExpr` in the function
`(*influxql.Field).Name()`
Fixes#5730.
A new attribute has been added to points to track how many points were
used to calculate that point. This is particularly useful for finding
the mean as we can then split mean calculation into two phases: one at
the shard level and a second at the shards level.
This optimization is now used so we don't have to hold so many points in
memory while calculating the mean.
The select call and the query executor would both calculate the time
range, but in separate ways. The query executor needed some way to pass
in the implicit end time that is placed there by the query executor.
Fixes#5636.
Derivatives rely on the underlying iterator to handle start and end
times. They do not perform them or organize points into groups. In
certain circumstances, the start time or end time that got implicitly
passed could be on an uneven interval with the first point returned by
the aggregate, which caused the entire iterator not to be read.
This fixes#5571.
Jonathan A. Sternberg
Jonathan A. Sternberg
Ben Johnson
Nathaniel Cook
Gabriel Levine
Joe LeGasse
Jack Zampolin
Seif Lotfy