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Add the following counters: (1) querier_cache_lookups (2) querier_cache_misses (3) querier_cache_drops (4) querier_cache_time_based_evictions (5) querier_cache_resource_based_evictions (6) querier_cache_memory_based_evictions (6) querier_cache_population (1) counts the total number of querier cache lookups. Not all page-fetches will result in a querier lookup. For example the first page of a query will not do a lookup as there was no previous page to reuse the querier from. The second, and all subsequent pages however should attempt to reuse the querier from the previous page. (2) counts the subset of (1) where the read have missed the querier cache (failed to find a matching saved querier). (3) counts the subset of (1) where the querier was recalled and dropped immediately. This can happen for example if the querier was at the wrong position. (4) counts the cached queriers that were evicted due to their TTL expiring. (5) counts the cached queriers that were evicted due to reader-resource (those limited by reader-concurrency limits) shortage. (6) counts the cached queriers that were evicted due to reaching the cache's memory limits (currently set to 4% of the shards' memory). (7) is the current number of entries in the cache Note: * The count of cache hits can be derived from these counters as (1) - (2). * cache_drop (3) also implies a cache hit (see above). This means that the number of actually reused queriers is: (1) - (2) - (3)
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>