The test put a wrapping range into a non-wrapping range variable.
This was harmless at the time this test was written, but newer code
may not be as forgiving so better use a non-wrapping range as intended.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20170704103128.29689-1-nyh@scylladb.com>
When starting repair, we divided the large token ranges (vnodes) linto small
subranges of a desired length (around 100 partition), and built a huge list
of those subranges - to iterate over them later and compare checksums of
those chunks.
However, building this list up-front is completely unnecessary, and wastes
a lot of memory: In a test with 1 TB of data, as much as 3 gigabytes was
spent on this list. Instead, what we do in this patch is to find the next
chunk in a DFS-like splitting algorithm, using only the token range
midpoint() function (as before). The amount of memory needed for this is
O(logN), instead of O(N) in the previous implementation.
Refs #2430.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Right now, next_token_for_shard() only allows iterating linearly in shard
order. Add the ability to select a specific shard to skip to (in case we're
only interested in a single shard), and to select larger ranges (so that
exponential increases are not implemented by iteration).
Sharding on the most significant token bits aliases with the vnode mechanism,
which also uses the most significant bits; this requires a huge number of
vnodes to achieve good sharding.
This patch teaches the murmur3 partitioner to ignore the most significant
N bits when calculating a token's hard, so we use token bits which still have
some entropy. In effect, with changes the token range layout from
shard 0
shard 1
...
shard S-1
to
shard 0
shard 1
...
shard S-1
shard 0
shard 1
...
shard S-1
...
shard 0
shard 1
...
shard S-1
Where the number of repetitions of the block is 2^(ignored msb bits).
For compatibility, the default is zero ignored bits, matching the pre-patch
state, until we wire things up.
Cassandra 1.x clusters often use RandomPartitioner. Supporting
RandomPartitioner will allow easier migration to Scylla
Tests are added to make sure scylla generates the same token as
Cassandra does for the same partition key.
Fixes#1438
Message-Id: <3bc8b7f06fad16d59aaaa96e2827198ce74214c6.1469166766.git.asias@scylladb.com>
In order to support ByteOrderedPartitioner, we need to implement the
missing describe_ownership and midpoint function in
byte_ordered_partitioner class.
As a starter, this path uses a simple node token distance based method
to calculate ownership. C* uses a complicated key samples based method.
We can switch to what C* does later.
Tests are added to tests/partitioner_test.cc.
Fixes#1378
The midpoint() algorithm to find a token between two tokens doesn't
work correctly in case of wraparound. The code tried to handle this
case, but did it wrong. So this patch fixes the midpoint() algorithm,
and adds clearer comments about why the fixed algorithm is correct.
This patch also modifies two midpoint() tests in partitioner_test,
which were incorrect - they verified that midpoint() returns some expected
values, but expected values were wrong!
We also add to the test a more fundemental test of midpoint() correctness,
which doesn't check the midpoint against a known value (which is easy to
get wrong, like indeed happened); Rather we simply check that the midpoint
is really inside the range (according to the token ordering operator).
This simple test failed with the old implementation of midpoint() and
passes with the new one.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
