Checking bloom filters of sstables to compute max purgeable timestamp
for compaction is expensive in terms of CPU time. We can avoid
calculating it if we're not about to GC any tombstone.
This patch changes compacting functions to accept a function instead
of ready value for max_purgeable.
I verified that bloom filter operations no longer appear on flame
graphs during compaction-heavy workload (without tombstones).
Refs #1322.
We want the node's schema version to change whenever
table_schema_version of any table changes. The latter is calculated by
hashing mutations so we should also use mutation hash when calculating
schema digest.
The version needs to change value not only on structural changes but
also temporal. This is needed for nodes to detect if the version they
see was already synchronized with or not even if it has the same
structure as the past versions. We also need to end up with the same
version on all nodes when schema changes are commuted.
For regular mutable schemas version will be calculated from underlying
mutations when schema is announced. For static schemas of system
keyspace it is calculated by hashing scylla version and column id,
because we don't have mutations at the time of building the schema.
We will be able to reuse the code in frozen_schema. We need to read
data in mutation form so that we can construct the correct
schema_table_version, and attach the mutations to schema_ptr.
It simplifies add_table_to_schema_mutation() interface.
The current code is also a bit confusing, partition_key is created
with the keyspaces() schema and used in mutations destined for the
columnfamilies() schema. It works, the types are the same, but looks a
bit scary.
All database code was converted to is when storage_proxy was made
distributed, but then new code was written to use storage_proxy& again.
Passing distributed<> object is safer since it can be passed between
shards safely. There was a patch to fix one such case yesterday, I found
one more while converting.
There's nothing legacy about it so rename legacy_schema_tables to
schema_tables. The naming comes from a Cassandra 3.x development branch
which is not relevant for us in the near future.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
