FT.AGGREGATE COLLECT reducer example

This example demonstrates the COLLECT reducer for FT.AGGREGATE: a GROUPBY reducer that, within each group, projects a chosen set of fields from every row — optionally deduplicated, sorted and limited — and returns them as an array of per-entry maps under the reducer alias. A single aggregation can therefore return each group and its top-N members.

Prerequisites

Redis 8.8+ with the Search module, listening on localhost:6379. COLLECT is gated behind unstable search features; the example enables the gate itself with CONFIG SET search-enable-unstable-features yes.

The client is configured with Protocol: 2 because the RESP3 response shape of FT.AGGREGATE is still marked unstable; set UnstableResp3: true instead if you want to use RESP3. AggregateRow.Collect decodes both the RESP2 and RESP3 entry shapes, so no other code changes are needed.

Run

go run .

The example:

1. Creates an index idx:products over hashes prefixed with product:.
2. Seeds 10 products with name, category, brand, price, rating.
3. Runs two aggregations:
   • Top-2 per category (options struct) — GROUPBY @category with REDUCE COLLECT ... FIELDS 2 @name @price SORTBY 2 @rating DESC LIMIT 0 2, built with redis.NewCollectReducer next to a plain COUNT reducer.
   • Whole documents per brand (builder) — LOAD * → GROUPBY @brand → COLLECT FIELDS *, expressed with the fluent AggregateBuilder.Collect. (On current unstable server builds, SORTBY combined with FIELDS * drops the sort field from the entries — sort with an explicit field list instead, as in the first query.)

Replies are decoded with AggregateRow.Collect, which returns the collected entries as []map[string]interface{} regardless of protocol.