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Redis Repositories Anatomy
Redis as a store itself offers a very narrow low-level API leaving higher level functions, such as secondary indexes and query operations, up to the user.
This section provides a more detailed view of commands issued by the repository abstraction for a better understanding of potential performance implications.
Consider the following entity class as the starting point for all operations:
Example 1. Example entity
@RedisHash("people")
public class Person {
@Id String id;
@Indexed String firstname;
String lastname;
Address hometown;
}
public class Address {
@GeoIndexed Point location;
}
Insert new
repository.save(new Person("rand", "al'thor"));
HMSET "people:19315449-cda2-4f5c-b696-9cb8018fa1f9" "_class" "Person" "id" "19315449-cda2-4f5c-b696-9cb8018fa1f9" "firstname" "rand" "lastname" "al'thor" (1)
SADD "people" "19315449-cda2-4f5c-b696-9cb8018fa1f9" (2)
SADD "people:firstname:rand" "19315449-cda2-4f5c-b696-9cb8018fa1f9" (3)
SADD "people:19315449-cda2-4f5c-b696-9cb8018fa1f9:idx" "people:firstname:rand" (4)
1 | Save the flattened entry as hash. |
2 | Add the key of the hash written in <1> to the helper index of entities in the same keyspace. |
3 | Add the key of the hash written in <2> to the secondary index of firstnames with the properties value. |
4 | Add the index of <3> to the set of helper structures for entry to keep track of indexes to clean on delete/update. |
Replace existing
repository.save(new Person("e82908cf-e7d3-47c2-9eec-b4e0967ad0c9", "Dragon Reborn", "al'thor"));
DEL "people:e82908cf-e7d3-47c2-9eec-b4e0967ad0c9" (1)
HMSET "people:e82908cf-e7d3-47c2-9eec-b4e0967ad0c9" "_class" "Person" "id" "e82908cf-e7d3-47c2-9eec-b4e0967ad0c9" "firstname" "Dragon Reborn" "lastname" "al'thor" (2)
SADD "people" "e82908cf-e7d3-47c2-9eec-b4e0967ad0c9" (3)
SMEMBERS "people:e82908cf-e7d3-47c2-9eec-b4e0967ad0c9:idx" (4)
TYPE "people:firstname:rand" (5)
SREM "people:firstname:rand" "e82908cf-e7d3-47c2-9eec-b4e0967ad0c9" (6)
DEL "people:e82908cf-e7d3-47c2-9eec-b4e0967ad0c9:idx" (7)
SADD "people:firstname:Dragon Reborn" "e82908cf-e7d3-47c2-9eec-b4e0967ad0c9" (8)
SADD "people:e82908cf-e7d3-47c2-9eec-b4e0967ad0c9:idx" "people:firstname:Dragon Reborn" (9)
1 | Remove the existing hash to avoid leftovers of hash keys potentially no longer present. |
2 | Save the flattened entry as hash. |
3 | Add the key of the hash written in <1> to the helper index of entities in the same keyspace. |
4 | Get existing index structures that might need to be updated. |
5 | Check if the index exists and what type it is (text, geo, …). |
6 | Remove a potentially existing key from the index. |
7 | Remove the helper holding index information. |
8 | Add the key of the hash added in <2> to the secondary index of firstnames with the properties value. |
9 | Add the index of <6> to the set of helper structures for entry to keep track of indexes to clean on delete/update. |
Save Geo Data
Geo indexes follow the same rules as normal text based ones but use geo structure to store values. Saving an entity that uses a Geo-indexed property results in the following commands:
GEOADD "people:hometown:location" "13.361389" "38.115556" "76900e94-b057-44bc-abcf-8126d51a621b" (1)
SADD "people:76900e94-b057-44bc-abcf-8126d51a621b:idx" "people:hometown:location" (2)
1 | Add the key of the saved entry to the the geo index. |
2 | Keep track of the index structure. |
Find using simple index
repository.findByFirstname("egwene");
SINTER "people:firstname:egwene" (1)
HGETALL "people:d70091b5-0b9a-4c0a-9551-519e61bc9ef3" (2)
HGETALL ...
1 | Fetch keys contained in the secondary index. |
2 | Fetch each key returned by <1> individually. |
Find using Geo Index
repository.findByHometownLocationNear(new Point(15, 37), new Distance(200, KILOMETERS));
GEORADIUS "people:hometown:location" "15.0" "37.0" "200.0" "km" (1)
HGETALL "people:76900e94-b057-44bc-abcf-8126d51a621b" (2)
HGETALL ...
1 | Fetch keys contained in the secondary index. |
2 | Fetch each key returned by <1> individually. |