Just in case the new algorithm turns out to be buggy, or give a
performance regression, add a flag to fall-back to the old algorithm for
use in the field.
Closes#9908
* github.com:scylladb/scylla:
db: config: add a flag to disable new reversed reads algorithm
replica: table: remove obsolete comment about reversed reads
Just in case the new algorithm turns out to be buggy, or give a
performance regression, add a flag to fall-back to the old algorithm for
use in the field.
Mirroring replica::database::get_keyspaces(), for Thrift's use.
We return a vector instead of a hash map. Random access is already
available via database::find_keyspace(). The name is available
via the keyspace metadata, and in fact Thrift ignore the map
name and uses the metadata name. Using a simpler type reduces
include dependencies for this heavily used module.
The function is plumbed to replica::database::get_keyspaces() so
it returns the same data.
Fixes#9408
While it is rare, some customer issues have shown that we can run into cases
where commit log apply (writing mutations to it) fails badly. In the known
cases, due to oversized mutations. While these should have been caught earlier
in the call chain really, it would probably help both end users and us (trying
to figure out how they got so big and how they got so far) iff we added info
to the errors thrown (and printed), such as ks, cf, and mutation content.
Somewhat controversial. Making the apply with CL decision path
coroutinized, mainly to be able to in next patch make error handling
more informative (because we will have exceptions that are immediate
and/or futurized).
This is as stated somewhat problematic, it adds an allocation to
perf_simple_query::write path (because of crap clang cr frame folding?).
However, tasks/op remain constant and actual tps (though unstable)
remain more or less the same (on my crappy measurements).
Counter path is unaffected, as coroutine frame alloc replaces with(...)
alloc, and all is same and dandy.
I am hoping that the simpler error + verbose code will compensate for
the extra alloc.
Mechanical changes and a resulting downgrade in one caller (which is
itself converted later).
Signed-off-by: Michael Livshin <michael.livshin@scylladb.com>
Move replica-oriented classes to the replica namespace. The main
classes moved are ::database, ::keyspace, and ::table, but a few
ancillary classes are also moved. There are certainly classes that
should be moved but aren't (like distributed_loader) but we have
to start somewhere.
References are adjusted treewide. In many cases, it is obvious that
a call site should not access the replica (but the data_dictionary
instead), but that is left for separate work.
scylla-gdb.py is adjusted to look for both the new and old names.
The database, keyspace, and table classes represent the replica-only
part of the objects after which they are named. Reading from a table
doesn't give you the full data, just the replica's view, and it is not
consistent since reconciliation is applied on the coordinator.
As a first step in acknowledging this, move the related files to
a replica/ subdirectory.
