mirrors/scylladb
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Optimize sstable::as_mutation_source() for one partition

Browse Source 
Although usually one can fast_forward_to() on the result of a
sstable::as_mutation_source(), earlier we had an optimization
where if a single partition was specified, it was read exactly,
and fast_forward_to() was *NOT* allowed.

With the mutation_reader::forwarding flag patch, when this flag
was on - requesting fast_forward_to() - we disabled this optimization.
This makes sense, but is not backward compatible with the code which
previously assumes this optimization exists... So this patch returns
this optimization, despite this meaning that we blatently ignore
the fwd_mr flag in that case.

Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20170620081107.14335-1-nyh@scylladb.com>
This commit is contained in:
Nadav Har'El
2017-06-20 11:11:07 +03:00
committed by Tomasz Grabiec
parent ba0ba87bf9
commit 186f031187
1 changed files with 5 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
sstables/sstables.cc
View File

@@ -2826,7 +2826,11 @@ mutation_source sstable::as_mutation_source() {
tracing::trace_state_ptr trace_ptr,
streamed_mutation::forwarding fwd,
::mutation_reader::forwarding fwd_mr) mutable {
if (!fwd_mr && range.is_singular() && range.start()->value().has_key()) {
// CAVEAT: if as_mutation_source() is called on a single partition
// we want to optimize and read exactly this partition. As a
// consequence, fast_forward_to() will *NOT* work on the result,
// regardless of what the fwd_mr parameter says.
if (range.is_singular() && range.start()->value().has_key()) {
const dht::ring_position& pos = range.start()->value();
return make_mutation_reader<single_partition_reader_adaptor>(sst, s, pos, slice, pc, fwd);
} else {