What is RedisGears?#

RedisGears is a programmable serverless engine for transaction, batch, and event-driven data processing allowing users to write and run their own functions on data stored in Redis.

Functions can be implemented in different languages, including Python and C, and can be executed by the RedisGears engine in one of two ways:

  1. 1.Batch: triggered by the Run action, execution is immediate and on existing data
  2. 2.Event: triggered by the Register action, execution is triggered by new events and on their data

Some batch type operations RedisGears can do:

  • Run an operation on all keys in the KeySpace or keys matching a certain pattern like :
    • Prefix all KeyNames with person:
    • Delete all keys whose value is smaller than zero
    • Write all the KeyNames starting with person: to a set
  • Run a set of operations on all(or matched) keys where the output of one operation is the input of another like
    • Find all keys with a prefix person: (assume all of them are of type hash)
    • Increase user's days_old by 1, then sum them by age group (10-20, 20-30 etc.)
    • Add today's stats to the sorted set of every client, calculate last 7 days average and save the computed result in a string

Some event type operations RedisGears can do:

  • RedisGears can also register event listeners that will trigger a function execution every time a watched key is changed like
    • Listen for all operations on all keys and keep a list of all KeyNames in the KeySpace
    • Listen for DEL operations on keys with a prefix I-AM-IMPORTANT: and asynchronously dump them in a "deleted keys" log file
    • Listen for all HINCRBY operations on the element score of keys with a prefix player: and synchronously update a user's level when the score reaches 1000

How do I use RedisGears?#

Run the Docker container:

docker run -p 6379:6379 redislabs/redisgears:latest

For a very simple example that lists all keys in your Redis database with a prefix of person: create the following python script and name it hello_gears.py :

gb = GearsBuilder() gb.run('person:*')

Execute your function:

docker exec -i redisgears redis-cli RG.PYEXECUTE "`cat hello_gears.py`"

Using gears-cli#

The gears-cli tool provides an easier way to execute RedisGears functions, specially if you need to pass some parameters too.

It's written in Python and can be installed with pip:

pip install gears-cli
gears-cli hello_gears.py REQUIREMENTS rgsync


gears-cli --help
usage: gears-cli [-h] [--host HOST] [--port PORT]
[--requirements REQUIREMENTS] [--password PASSWORD] path [extra_args [extra_args ...]]

RedisGears references#