InfluxDB Line Protocol Listener for PostgreSQL
A simple InfluxDB line protocol listener.
This is a very basic example of an extension that listens for data on a socket and writes it to the database.
It is an ongoing experimental work for educational purposes and as such there are no guarantees regarding feasability for any specific purpose, including its intended use.
Building and Installing
To install the dependencies it is easiest to install the PGDG version of the packages. Using the instructions from PostgreSQL Apt Repository would look like this:
sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update
sudo apt-get -y install postgresql postgresql-server-dev-13After the dependencies are installed, To build and install the extension:
git clone git@github.com:mkindahl/pg_influx.git
cd pg_influx
make
sudo make install
Running Regression Tests
To run the regression tests
make installcheck
InfluxDB Line Protocol
The listener uses the Influx line protocol, which is a simple protocol for sending metric data that is supported by Telegraf.
Each line of the line protocol consists of lines of the format:
measurementName,tagKey=tagValue fieldKey="fieldValue" 1465839830100400200
There is a single measurement name (also called "metric"), zero or more tag keys with values, and at least one field with a field value. The timestamp is optional, and is given in nanoseconds since the epoch. When parsing the line, quotes are removed from any quoted field value before being used as a literal string.
The grammar is very simple, but we use an even more simplified
version. We allow \ to escape any character in values and keys and
the actual interpretation of the strings will be done at a later
stage, so we do not bother about distinguishing integers from
floating-point numbers, nor bare strings from quoted strings (but we
remove the quotes).
Line = Ident, {",", Item}, " ", Item, {",", Item};
Item = Ident, "=", Value;
Ident = LETTER, {LETTER | DIGIT | "_" | "-"};
Value = QString | BString;
BString = LETTER, {"\", ANY | VALUE_CHAR};
QString = '"', {"\", ANY | STRING_CHAR}, '"';
VALUE_CHAR = ? any character except space, comma, or backslash ?;
STRING_CHAR = ? any character except quote or backslash ?;
LETTER = ? any letter ?;
DIGIT = ? any digit ?;