README.md

Juttle PostgreSQL Adapter

PostgreSQL adapter for the Juttle data flow language, with read & write support.

Examples

Read rows from your logs SQL table where the log level is info, with the

read postgres -table 'logs' level = 'info'

Perform an equivalent query using the -raw option:

read postgres -raw 'select * from "logs" where "level" = "info" limit 10000'

Add a debug option to return the final SQL query instead (before any pagination):

read postgres -table "logs" -debug true level = "info"

will output: {query: 'select * from "logs" where "level" = 'info' limit 10000'}.

If you have time series data in your table, indicate the column with the timestamp using the timeField option to paginate and sort data correctly:

read postgres -timeField "create_time" -table "logs";
read postgres -timeField "create_time" -table "logs -from :2 days ago: -to :1 hour ago:;"

The content of the column indicated by timeField will appear as the time field in resulting points.

An end-to-end example is described here and deployed to the demo system demo.juttle.io.

Installation

Like Juttle itself, the adapter is installed as a npm package. Both Juttle and the adapter need to be installed side-by-side:

$ npm install juttle
$ npm install juttle-postgres-adapter

Configuration

The adapter needs to be registered and configured so that it can be used from within Juttle. To do so, use the following format when adding a Postgres configuration to your ~/.juttle/config.json file:

{
    "adapters": {
        "postgres": [{
            "hostname": "localhost",
            "port": 5432,
            "user": "postgres",
            "pw": "",
            "db": "postgres",
            "id": "default"
        }]
    }
}

Read options

Name	Type	Required	Description
table	string	yes	table to query
raw	string	no	send a raw SQL query to PostgreSQL
debug	boolean	no	output a query corresponding to current set of options and filters
timeField	string	no	assume date time column, to and from options will use this to limit rows by time. Include this option to sort results by time.
fetchSize	integer	no	row limit, defaults to 10000 records
from	moment	no	select points after this time (inclusive)
to	moment	no	select points before this time (exclusive)
db	string	no	select the database name to use in your instance
id	string	no	select the config instance to use

Write options

Name	Type	Required	Description
table	string	yes	table to write points into
db	string	no	select the database name to use in your instance
id	string	no	select the config instance to use

Numeric Types

When reading numeric data types of variable storage size from PostgreSQL, values are treated as type String in juttle. You may want to use Number.fromString() function in the juttle program if your data has numbers of these types. When juttle reads fields of PostgreSQL real and double precision types, their values are treated as numbers.

Time Zones

Use the timestamp with time zone date type in your postgres table to avoid time zone confusion. If your timestamp value does not have a time zone, Postgres will use the local system TimeZone parameter and then convert to UTC.

Contributing

Contributions are welcome! Please file an issue or open a pull request.

To check code style and run unit tests:

npm test

Both are run automatically by Travis.