Redis Sorted Object Set (Sorted Hashes)

We all know that the best way to store objects in Redis is through, Redis hashes. Redis sorted sets are used to keep a sorted set with a given score for each value. What if we need a sorted set of objects? What we need is a “Sorted set of Objects”, which Redis does not support by default. We came up with a hybrid, simple data structure that allows sorted objects using Redis Hashes and Redis Sorted sets.

Use of Redis Hashes

Here we will keep an object as a Redis hash. Think of a simple object with several values as shown below.

TICKET1 {     
    MERCHANT_ID: 0123456789,     
    TIME_STAMP: 00000000000,     
    SALE: 12.32 
}

This will be saved in the Redis

HMSET TICKET1 MERCHANT_ID "0123456789" TIME_STAMP "00000000000" SALE "12.32"

When we need to edit an existing value and add a new value it can be done below

// Adding a new value
HSET TICKET1 DISCOUNT "0.60"
 
// Set Multiple Values
HMSET TICKET1 DISCOUNT "0.50" SALE "12.60"
 
// Set single Value
HSET TICKET1 SALE "12.50"
 
// RESULT
TICKET1 {
    MERCHANT_ID: 0123456789,
    TIME_STAMP: 00000000000,
    SALE: 12.50,
    DISCOUNT: 0.50
}

Getting full map and some selected value

// Get the full object
HGETALL TICKET1

1) "MERCHANT_ID" 
2) "0123456789" 
3) "TIME_STAMP" 
4) "00000000000" 
...   

// Get set of selected subset of values 
HMGET TICKET1 MERCHANT_ID SALE   
1) "0123456789" 
2) "12.50"   

// get a single value 
HGET DISCOUNT   
1) "0.50"

Whole map or items can be deleted

// Delete one field
HDEL TICKET1 SALE
 
// Delete whole object
DEL TICKET1

There is some more commands in the Redis hash that can help us in this process

Use of Redis Sorted Sets

As we said above we need to search with time values and in-order searches. This cannot be done alone by Redis hashes. Here we keep a list of all keys in the Redis hashes as a sorted set. This allow us to get all the maps that came after some time stamp. or between two time stamps. Other than that this allows us to search under topics (EX: get all TICKETS after 00000001 time stamp)

ZADD TICKETS 1459746182 "TICKET1"
ZADD TICKETLINES 1459746192 "TICKETLINE1"
ZADD TICKETLINES 1459746222 "TICKETLINE2"
ZADD TICKETS 1459746282 "TICKET2"
ZADD TICKETS 1459746382 "TICKET3"

Get items under one topic within a given time range

ZRANGE TICKETS 1459746282 -1
1) "TICKET2"
2) "TICKET3"

There is some more commands in the Redis hash that can help us in this process