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a4218f536b
`query_partition_key_range()` does the final result merging and trimming
(if necessary) to make sure we don't send more rows to the client than
requested. This merging and trimming is done by a continuation attached
to the `query_partition_key_range_concurrent()` which does the actual
querying. The continuations captures via value the `row_limit` and
`partition_limit` fields of the `query::read_command` object of the
query. This has an unexpected consequence. The lambda object is
constructed after the call to `query_partition_key_range_concurrent()`
returns. If this call doesn't defer, any modifications done to the read
command object done by `query_partition_key_range_concurrent()` will be
visible to the lambda. This is undesirable because
`query_partition_key_range_concurrent()` updates the read command object
directly as the vnodes are traversed which in turn will result in the
lambda doing the final trimming according to a decremented `row_limits`,
which will cause the paging logic to declare the query as exhausted
prematurely because the page will not be full.
To avoid all this make a copy of the relevant limit fields before
`query_partition_key_range_concurrent()` is called and pass these copies
to the continuation, thus ensuring that the final trimming will be done
according to the original page limits.
Spotted while investigating a dtest failure on my 1865/range-scans/v2
branch. On that branch the way range scans are executed on replicas is
completely refactored. These changes appearantly reduce the number of
continuations in the read path to the point where an entire page can be
filled without deferring and thus causing the problem to surface.
Fixes #3605.
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <f11e80a6bf8089d49ba3c112b25a69edf1a92231.1531743940.git.bdenes@scylladb.com>
(cherry picked from commit cc4acb6e26)
Scylla
Quick-start
$ git submodule update --init --recursive
$ sudo ./install-dependencies.sh
$ ./configure.py --mode=release
$ ninja-build -j4 # Assuming 4 system threads.
$ ./build/release/scylla
$ # Rejoice!
Please see HACKING.md for detailed information on building and developing Scylla.
Running Scylla
- Run Scylla
./build/release/scylla
- run Scylla with one CPU and ./tmp as data directory
./build/release/scylla --datadir tmp --commitlog-directory tmp --smp 1
- For more run options:
./build/release/scylla --help
Building Fedora RPM
As a pre-requisite, you need to install Mock on your machine:
# Install mock:
sudo yum install mock
# Add user to the "mock" group:
usermod -a -G mock $USER && newgrp mock
Then, to build an RPM, run:
./dist/redhat/build_rpm.sh
The built RPM is stored in /var/lib/mock/<configuration>/result directory.
For example, on Fedora 21 mock reports the following:
INFO: Done(scylla-server-0.00-1.fc21.src.rpm) Config(default) 20 minutes 7 seconds
INFO: Results and/or logs in: /var/lib/mock/fedora-21-x86_64/result
Building Fedora-based Docker image
Build a Docker image with:
cd dist/docker
docker build -t <image-name> .
Run the image with:
docker run -p $(hostname -i):9042:9042 -i -t <image name>