Redis XADD in Ruby (Detailed Guide w/ Code Examples)

Use Case(s)

The XADD command in Redis is used with the Streams data type. It appends new entries to a stream. Common use cases include:

1. Logging systems: where each log entry is added as a new message.
2. Data streaming: continuously capturing real-time data.

Code Examples

Here's a basic usage of the XADD command using Ruby:

require 'redis'

redis = Redis.new

# Add an entry to the stream 'mystream'
redis.xadd('mystream', '*', 'key1', 'value1', 'key2', 'value2')

In this example, we're adding an entry to the stream named 'mystream'. The '*' generates an ID based on the current timestamp. 'key1' and 'key2' represent field names and 'value1' and 'value2' are their respective values.

To add multiple messages at once:

require 'redis'

redis = Redis.new

# Add multiple entries to the stream 'mystream'
fields_values = ['key1', 'value1', 'key2', 'value2']
fields_values2 = ['key3', 'value3', 'key4', 'value4']

redis.xadd('mystream', '*', *fields_values)
redis.xadd('mystream', '*', *fields_values2)

This will add two separate entries to 'mystream', each with their own unique IDs and key-value pairs.

Best Practices

1. Keep your streams and entries adequately small for efficient memory usage.
2. If possible, use auto-generated IDs ('*') instead of manually inputted ones for better performance and uniqueness.

Common Mistakes

1. Trying to add an entry to a non-existent stream. Redis will automatically create the stream if it doesn't exist.
2. Using large-sized data in streams which can lead to memory inefficiency.

FAQs

Q: Can I use XADD with other data types? A: No, XADD is specifically designed for use with Redis Streams.

Q: What happens if I try to add an entry to a non-existent stream? A: Redis will automatically create the stream.

Q: How many fields can I add to a stream entry? A: There's no hard limit, but remember that each additional field consumes more memory.