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A previous patch fixed Alternator's writes to use the timestamp provided by LWT instead of the current timestamp. That patch fixed the PutItem, DeleteItem and UpdateItem operations - and this patch fixes the remaining write operation: BatchWriteItems. So, Fixes #5653. Unfortunatly, the requirements of both BatchWriteItems and LWT make the resulting code - and this patch - somewhat inelegant. BatchWriteItems requires that we prepare all the operations first - failing if any of them has an error. Before this patch, the result of this preparation was an array of mutations, which in a second step we wrote to the database. But we can no longer use mutations for the result of the first step, because creating a mutation requires knowing the timestamp, which we don't know during the preparate phase - we will only know it during the later LWT operation. So now we need to invent a new intermediate format between the request and the mutation. This intermediate format is further complicated by the need to be send it between shards (for LWT's shard forwarding) so it cannot, for example, contain a reference to a schema. The fact that different sub-operations need to be sent to different shards, and that different sub-operations may write to different tables, further complicate the book-keeping and gives us a bunch of funky-typed maps. But eventually it all fits together. After this patch, as before this patch, the same code (now called put_or_delete_item), is used to implement both the PutItem and DeleteItem stand-alone operation, and the BachWriteItems operation which includes a whole list of these PutItem and DeleteItem operation. This patch also includes two more tests in test_batch.py, which test two more corner tests we haven't tested before: One tests the capability of BatchWriteItems to write to more than one table. The other tests that BatchWriteItems can write an empty item (it is not surprising that it does, but we do have special code for this case, so we should test it). Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Scylla
Quick-start
To get the build going quickly, Scylla offers a frozen toolchain which would build and run Scylla using a pre-configured Docker image. Using the frozen toolchain will also isolate all of the installed dependencies in a Docker container. Assuming you have met the toolchain prerequisites, which is running Docker in user mode, building and running is as easy as:
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
$ ./tools/toolchain/dbuild ./build/release/scylla --developer-mode 1
Please see HACKING.md for detailed information on building and developing Scylla.
Note: GCC >= 8.1.1 is required to compile Scylla.
Running Scylla
- Run Scylla
./build/release/scylla
- run Scylla with one CPU and ./tmp as work directory
./build/release/scylla --workdir tmp --smp 1
- For more run options:
./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its APIs - CQL and Thrift. There is also experimental support for the API of Amazon DynamoDB, but being experimental it needs to be explicitly enabled to be used. For more information on how to enable the experimental DynamoDB compatibility in Scylla, and the current limitations of this feature, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found in ./docs and on the wiki. There is currently no clear definition of what goes where, so when looking for something be sure to check both. Seastar documentation can be found here. User documentation can be found here.
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>