The QueryExecutor had a lot of dead code made obsolete by the query
engine refactor that has now been removed. The TSDBStore interface has
also been cleaned up so we can have multiple implementations of this
(such as a local and remote version).
A StatementExecutor interface has been created for adding custom
functionality to the QueryExecutor that may not be available in the open
source version. The QueryExecutor delegate all statement execution to
the StatementExecutor and the QueryExecutor will only keep track of
housekeeping. Implementing additional queries is as simple as wrapping
the cluster.StatementExecutor struct or replacing it with something
completely different.
The PointsWriter in the QueryExecutor has been changed to a simple
interface that implements the one method needed by the query executor.
This is to allow different PointsWriter implementations to be used by
the QueryExecutor. It has also been moved into the StatementExecutor
instead.
The TSDBStore interface has now been modified to contain the code for
creating an IteratorCreator. This is so the underlying TSDBStore can
implement different ways of accessing the underlying shards rather than
always having to access each shard individually (such as batch
requests).
Remove the show servers handling. This isn't a valid command in the open
source version of InfluxDB anymore.
The QueryManager interface is now built into QueryExecutor and is no
longer necessary. The StatementExecutor and QueryExecutor split allows
task management to much more easily be built into QueryExecutor rather
than as a separate struct.
This commit adds a configurable limit to the number of series that
can be returned from a `SELECT` statement. The limit is checked
immediately after planning and is determined by the use of iterator
stats.
Fixes#6076
Under highly conncurrent write load, the coordinating node would
create a connection to any other node that is part of the replica
group. Since each connection can be expensive, OOM sitations could
occur because there was no bounds on the number of new connections
that would be created. If writes on a remote node were slow, connections
could pile up an exacerbate the problem.
This switches the pool to be bounded and has a checkout that is blocking
with a timeout. If a connection is available, it's returned immediately.
If the pool still has room for more connections, it will create one if needed.
Otherwise, the call will block until a connection becomes available or
the timeout expires. In the case of a timeout, it is propogated back up
to the PointsWriter that determine what do return to the client.
With this change remote mapping no longer uses HTTP, as the HTTP ports
exposed by nodes on the cluster are not known cluster wide. The TCP
ports exposed by the cluster service are, so this change uses that
functionality. Each RemoteMapper has its own dedicated connection pool
for each node, and remote mapping TCP connections are in no way coupled
with query TCP connections.
Jonathan A. Sternberg
Ben Johnson
Jason Wilder
Philip O'Toole
Philip O'Toole