This PR adds a `StatusError` to the `pproto.RowResponse` type, which
allows a stream to pass an error on the stream (encoded into
the `RowResponse.StatusError`). This can be checked downstream
for matching `EOF` or `err != nil` and handled appropriately.
This is helpful mainly with the `RowResponse` reducers which run in
goroutines. Instead of trying to manage a separate channel of errors
from those goroutines, we just follow the grpc model and send the
error with the stream.
The check for field existence is not necessary; since we
add the `_id` field to every response then at the very
least that field will be returned.
This check was preventin a query like `select _id from ...`
from returning any results.
This pins us to the initial external release of molecula/ext, which
with any luck will be the only one. (Narrator: It was not to be the
only one.) We also use GOPRIVATE so we don't need a replace directive.
After a few experiments with pkg/plugin, I'm ready to concede that the
people warning me it was unsuitable for production use were in fact
correct.
In the brave new world, the "ext" package is moved to its own module
outside pilosa. This means that importing it doesn't imply any need to
version-check against pilosa; we can just use versioned copies of the
ext package, which can be public because it doesn't contain anything
we need to care about keeping proprietary.
Then we can, conditional on build tags, import modules from a
neighboring repo which contains the actual implementations, and if
they're imported, their init functions register them.
This PR is meant to get all columns from an index
based on the TrackExistence row.
`All()` is a PQL function that can be used as a typical
row object. Optional arguments are `limit` and `offset`.
This PR adds a field name (string) to the return types
which represent the values from a specific field. For example,
a TopN query on field `x` would be `TopN(x)` and have results
like:
```
[]Pair{
{ID: 14, Count: 10},
{ID: 3, Count: 8},
{ID: 7, Count: 3},
}
```
In order to know what field this result type refers to, we wrap
`[]Pair` in a new struct called `PairsField` which contains an
addition `Field` string where `x` is stored.
This is useful for informing the gRPC server how to construct
more appropriate headers for the result stream (in this case,
the column headers can now be "x" and "count").
Similar logic was applied to `RowIdentifiers` and `Pair` as well.
There is a TODO in the `StringWithSubj` method because the value
types really depend on the subject type (for example, `count` uses
uint64, while `sum` uses int64). I'm waiting to address this
until we decide how to handle sums of floats (Decimal), because
that will affect this logic as well.
This PR adds support for a `having` argument in a `GroupBy` query.
Usage looks like this:
```
GroupBy(Rows(a), having=Condition(count > 10))
GroupBy(Rows(a), aggregate=Sum(field=b), having=Condition(sum > 100))
```
In order to standardize results as streams of RowResponse,
this PR introduces two interfaces `StreamClient` and
`StreamServer`) which mirror the grpc stream interfaces.
Upstream users (sqlmapper, vdsm, etc) can implement
instances of these interfaces to ensure that results can
stream through the entire sytem in an expected way.
This PR also fixes a couple of missing data types.
