Post

Steve Lorello
@steve.slorello.com

TIL in RediSearch, if you are running an FT.AGGREGATE with a SORTBY, if you apply no MAX, it will only sort the first 10 records. github.com/redis/redis-... One of the really neat things about RediSearch is that it makes you really think about how you're querying your data in #redis.

github.comUnusual behavior of 'Count' with 'SORTBY' · Issue #502 · redis/redis-om-dotnetHi when I try use Count after Orderby cause return wrong result. Sample code is: /* * Redis-OM: 0.7.6 * dotnet core 8.0 * OS Program Run: Windows 10 22H2 * Redis Info: * redis_version:7.4.1 * redis...
Steve Lorello
@steve.slorello.com

First, for data modeling, you use FT.CREATE to create a secondary index on top of your data in Redis (either hashes or JSON). You need to consider the documents you want to index (we use prefixes for your keys to determine what you're indexing), then you specify precisely which fields to index.

0 reposts0 likes

Steve Lorello
@steve.slorello.com

Then when using FT.SEARCH to query your data you use the RediSearch query syntax to build a filter for your documents. FT.SEARCH forces you to think about how you're going to paginate your data, because by default it only returns the first 10 records matching your filter. Why's that you might ask?

Steve Lorello
@steve.slorello.com

Well, at Redis, we measure execution times in microseconds not milliseconds, by default anything that exceeds 10ms is considered "slow", and we want to be as aggressive as possible in servicing queries. The way indexes are structured in RediSearch, the time complexity of a query is:

Steve Lorello
@steve.slorello.com

O(N) in the size of the Result Set (the documents sent back to you). So, that's why we default to 10, we want some relatively small constant - which in strict time-complexity terms - removes the O(N) (as N is a constant), now you're bound to the access complexity of the index O(1) or O(log(N))

Steve Lorello
@steve.slorello.com

You can expand your page size with the LIMIT sub-command on FT.SEARCH e.g. LIMIT 100 200 goes to offset 100 in the result set and returns the next 200 documents. In Redis OM #dotnet one of the things I did was create enumerators that automagically paginate over the result set so you don't have to.