This is not complete, but it is a starting point for more thorough tests
of subqueries.
This also reorders the use of `cmp.Diff` so the `want` is first and
`got` is second. This way, the `want` shows up as a minus sign in the
diff rather than, confusingly, as a plus sign.
This adds support for math functions into the query language. Math
functions are special because they are transformations and do not access
the filesystem in the same way aggregate functions do. A transformation
takes one point and always outputs one point making it more similar to
binary expressions so these math functions follow the same rules as
binary expressions.
This also supports using math literals (so you can do `sin(1)`) and the
math functions can be used anywhere such as in a field or an expression.
Both of the following are supported:
SELECT sin(value) FROM cpu
SELECT value FROM cpu WHERE sin(value) > 0.5
Arguments are in radians. Degrees is not supported.
This change makes it so that we simplify the math engine so it doesn't
use a complicated set of nested iterators. That way, we have to change
math in one fewer place.
It also greatly simplifies the query engine as now we can create the
necessary iterators, join them by time, name, and tags, and then use the
cursor interface to read them and use eval to compute the result. It
makes it so the auxiliary iterators and all of their complexity can be
removed.
This also makes use of the new eval functionality that was recently
added to the influxql package.
No math functions have been added, but the scaffolding has been included
so things like trigonometry functions are just a single commit away.
This also introduces a small breaking change. Because of the call
optimization, it is now possible to use the same selector multiple times
as a selector. So if you do this:
SELECT max(value) * 2, max(value) / 2 FROM cpu
This will now return the timestamp of the max value rather than zero
since this query is considered to have only a single selector rather
than multiple separate selectors. If any aspect of the selector is
different, such as different selector functions or different arguments,
it will consider the selectors to be aggregates like the old behavior.
This also adds a small script to write out the dependencies to gdm.
These can be written with:
$ ./write-gdm-deps.sh > Godeps
This is a temporary script during the migration.
The dependency overrides have also been removed in favor of them being
locked by Gopkg.lock.