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https://github.com/dalmatinerdb/ddb_client
https://github.com/dalmatinerdb/ddb_client
Last synced: about 1 month ago
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- Host: GitHub
- URL: https://github.com/dalmatinerdb/ddb_client
- Owner: dalmatinerdb
- License: mit
- Created: 2014-12-11T03:44:46.000Z (about 10 years ago)
- Default Branch: master
- Last Pushed: 2018-03-06T00:57:18.000Z (almost 7 years ago)
- Last Synced: 2024-10-13T23:17:10.539Z (2 months ago)
- Language: Erlang
- Size: 207 KB
- Stars: 11
- Watchers: 5
- Forks: 6
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
## DalmatinerDB Client
An Erlang TCP client for the dalmatiner time series database.
Firstly, in order to read or write data it is necessary to open a connection:
```erlang
{ok, Con} = ddb_tcp:connect("127.0.0.1", 5555).
```
For efficiency reasons, the Dalmatiner TCP endpoint can only accept incoming data when switched to stream mode.
Therefore, in order to write data points, a connection needs to be swtiched to
stream mode as follows:
```erlang
Bucket = <<"my_bucket">>.
%% The delay is the time in seconds before connection is automatically flushed.
Delay = 1.
{ok, SCon} = ddb_tcp:stream_mode(Bucket, Delay, Con).
```
Values should first be encoded in binary format using the [mmath](https://github.com/dalmatinerdb/mmath) module,
before attempting to write:
```erlang
Timestamp = 1466072419.
Bucket = <<"my_bucket">>.
Metric = dproto:metric_from_list([<<"base">>, <<"cpu">>]).
Value = mmath_bin:from_list([63.9, 64.0, 64.1]).
{ok, SCon1} = ddb_tcp:send(Metric, Timestamp, Value, SCon).
```
A stream connection is not required in order to perform read operations. In
addition to listing metrics and buckets, data for a given point in time can
be read as follows:
```erlang
Timestamp = 1466072419.
Bucket = <<"my_bucket">>.
Metric = dproto:metric_from_list([<<"base">>, <<"cpu">>]).
Count = 3.
{ok, Data, Con1} = ddb_tcp:get(Bucket, Metric, Timestamp, Count, Con).
```
Finally, a connection should be closed when done:
```erlang
Con1 = ddb_tcp:close(Con).
```
For more information, please consult the [network protocol
documentation](http://dalmatinerdb.readthedocs.io/en/latest/proto.html).
## Read options
It is possible to specify consistency parameters for an individual read operation if so
required. The following options are available:
Read repair: `{rr, off}` - disables read repair for this get request
`{rr, on}` - ensures read repairs for this read request, even on recently written data
`{rr, default}` - will use the system defaults
Read quorum: `{r, n}` - will use the same value as N for this get request
`{r, R :: pos_integer()}` - will use the value 0 < R <= N for this get request
`{r, default}` - will use the system default for R
To use these options in a read request:
```erlang
Timestamp = 1466072419.
Bucket = <<"my_bucket">>.
Metric = dproto:metric_from_list([<<"base">>, <<"cpu">>]).
Count = 3.
Opts = [{rr, off}, {r, 1}].
{ok, Data, Con1} = ddb_tcp:get(Bucket, Metric, Timestamp, Count, Opts, Con).
```
## Connection pools
A DalmatinerDB connection is dedicated to send data to a single bucket. In cases
where data is written to many buckets at once, it is more efficient to
re-use an existing connection for a bucket instead of opening a new one.
Applications such as [Pooler](https://github.com/seth/pooler) may be used to
pool and share connections to DDB.
## Building the client
The client can be compiled using `rebar3`.
Linting rules are specified using the Elvis plugin, and lint rules may be
checked by running:
```
$ rebar3 as lint lint
```