To ensure isolation of operation when streaming a mutation from a
mutable source (such as cache or memtable) MVCC is used.
Each entry in memtable or cache is actually a list of used versions of
that entry. Incoming writes are either applied directly to the last
verion (if it wasn't being read by anyone) or preprended to the list
(if the former head was being read by someone). When reader finishes it
tries to squash versions together provided there is no other reader that
could prevent this.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
Originally, ranges for reversed queries were in descending order and
ranges for forward queries in ascending order. However,
streamed_mutations require them to always be in ascending order.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
The main user of this list is MVCC implementation in partition_version.cc.
The reason why boost::intrusive::list<> cannot be used is that tere is no
single owner of the list who could keep boost::intrusive::list<> object
alive. In the MVCC case there is at least one partition_entry object and
possibly multiple partition_snapshot objects which lifetime is independent
and the list must remain in a valid state as long as at least one of them
is alive.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
It is incorrect to update row_cache with a memtable that is also its
underlying storage. The reason for that is that after memtable is merged
into row_cache they share lsa region. Then when there is a cache miss
it asks underlying storage for data. This will result with memtable
reader running under row_cache allocation section. Since memtable reader
also uses allocation section the result is an assertion fault since
allocation sections from the same lsa region cannot be nested.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
With streamed_mutations a partition with many small rows doesn't stress
the cache as much as the test expects. Use large clustering rows instead.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
range_tombstone_stream encapsulates logic responsible for turning
range_tombstone_list into a stream of mutation_fragments and merging
that stream with a stream of clustering rows.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
Row markers and collections weren't filtered out even if they belonged
to a clustering row that shouldn't be in the result. The check whether
to include cell or not was done only for live and dead atomic cells.
This patch adds appropriate checks for collections and row markers.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
mutation_reader and streamed_mutation may use the same stream as a source
mutation_fragments and mutations themselves (this happens in sstable reader).
In such case asking for next streamed_mutation from mutation_reader would
invalidate all other streamed_mutations.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
streamed_mutation represents a mutation in a form of a stream of
mutation_fragments. streamed_mutation emits mutation fragments in the
order they should appear in the sstables, i.e. static row is always
the first one, then clustering rows and range tombstones are emitted
according to the lexicographical ordering of their clustering keys and
bounds of the range tombstones.
Range tombstones are disjoint, i.e. after emitting
range_tombstone_begin it is guaranteed that there is going to be a
single range_tombstone_end before another range_tombstone_begin is
emitted.
The ordering of mutation_fragments also guarantees that by the time
the consumer sees a clustering row it has already received all
relevant tombstones.
Partition key and partition tombstone are not streamed and is part of
the streamed_mutation itself.
streamed_mutation uses batching. The mutation implementations are
supposed to fill a buffer with mutation fragments until is_buffer_full()
or the end of stream is encountered.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
This commit introduces mutation_fragment class which represents the parts
of mutation streamed by streamed_mutation.
mutation_fragment can be:
- a static row (only one in the mutation)
- a clustering row
- start of range tombstone
- end of range rombstone
There is an ordering (implemented in position_in_partition class) between
mutation_fragment objects. It reflects the order in which content of
partition appears in the sstables.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
After commit faa4581, each shard only starts splitting its shared sstables
after opening all sstables. This was important because compaction needs to
be aware of all sstables.
However, another bug remained: If one shard finishes loading its sstables
and starts the splitting compactions, and in parallel a different shard is
still opening sstables - the second shard might find a half-written sstable
being written by the first shard, and abort on a malformed sstable.
So in this patch we start the shared sstable rewrites - on all shards -
only after all shards finished loading their sstables. Doing this is easy,
because main.cc already contains a list of sequential steps where each
uses invoke_on_all() to make sure the step completes on all shards before
continuing to the next step.
Fixes#1371
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <1466426641-3972-1-git-send-email-nyh@scylladb.com>
Using an ordering mechanism better than rw-locks for write/flush
means we can wait for pending write in batch mode, and coalesce
data from more than one mutation into a chunk.
It also means we can wait for a specific read+flush pair (based on
file position).
Downside is that we will not do parallel writes in batch mode (unless
we run out of buffer), which might underutilize the disk bandwidth.
Upside is that running in batch mode (i.e. per-write consistency)
now has way better bandwidth, and also, at least with high mutation
rate, better average latency.
Message-Id: <1465990064-2258-1-git-send-email-calle@scylladb.com>
Scylla will not start if the disk was not benchmarked
so start run io_tune with the right parameters.
Also add the cpu_set environment variables for passing
cpu set to iotune and scylla.
Signed-of-by: Benoît Canet <benoit@scylladb.com>
Message-Id: <1466412846-4760-2-git-send-email-benoit@scylladb.com>
Use the PermissionsStartOnly systemd option to apply the permission
related configurations only to the start command. This allows us to stop
using "sudo" for ExecStartPre and ExecStopPost hooks and drop the
"requiretty" /etc/sudoers hack from Scylla's RPM.
Tested-by: Takuya ASADA <syuu@scylladb.com>
Message-Id: <1466407587-31734-1-git-send-email-penberg@scylladb.com>
Because we build on CentOS 7, which does not have the %sysctl_apply macro,
the macro is not expanded, and therefore executed incorrectly even on 7.2,
which does.
Fix by expanding the macro manually.
Fixes#1360.
Message-Id: <1466250006-19476-1-git-send-email-avi@scylladb.com>
