/redis-search

Use DIALECT 2 for Query Syntax

Pass DIALECT 2 on every FT.SEARCH / FT.AGGREGATE / FT.HYBRID call. From Redis 8 onward, DIALECT 2 is the only supported value — dialects 1, 3, and 4 are deprecated and removed in current Redis Open Source. Vector query attributes (the =>[KNN ...] form) require DIALECT 2 to parse.

Correct: Specify DIALECT 2 explicitly, or rely on modern client defaults.

# In raw commands, specify DIALECT 2 at the end
FT.SEARCH idx:bicycle "@model:hyperion" DIALECT 2

FT.AGGREGATE idx:bicycle "@type:{mountain}"
    GROUPBY 1 @brand
    REDUCE COUNT 0 AS bike_count
    DIALECT 2

Note on Redis 8 and DIALECT: Redis 8 (built-in Redis Search) accepts only DIALECT 2. The DEFAULT_DIALECT FT.CONFIG knob no longer accepts other values. Older Redis 7.x / RediSearch-module deployments still respect dialect 1; if you target both, set DIALECT 2 explicitly so behavior is identical across versions.

Why DIALECT 2:

• Required for vector search (=>[KNN ...] attribute syntax).
• Required for PARAMS placeholder binding.
• Predictable handling of special characters and NULL-like missing fields.
• The only dialect that will be supported going forward.

Incorrect: Relying on the server-side default with a client library that pins an older dialect.

# Bad: omitting DIALECT in a vector query with a legacy redis-py — falls back to DIALECT 1 and rejects =>[KNN ...]
FT.SEARCH idx:bicycle "*=>[KNN 10 @embedding $vec AS score]" PARAMS 2 vec "..."

Client mirrors

# redis-py — STEP_START dialect
# Mirrors doctests/search_quickstart.py
from redis import Redis
r = Redis()
# Modern redis-py defaults to DIALECT 2; set explicitly when in doubt
r.ft("idx:bicycle").search("@model:hyperion", dialect=2)
# STEP_END

// Jedis — STEP_START dialect
// Mirrors SearchQuickstartExample.java
import redis.clients.jedis.UnifiedJedis;
import redis.clients.jedis.search.FTSearchParams;
import redis.clients.jedis.search.SearchResult;

try (UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379")) {
    SearchResult res = jedis.ftSearch("idx:bicycle",
        "@model:hyperion",
        FTSearchParams.searchParams().dialect(2));
}
// STEP_END

Upstream sources

• redis-py: doctests/search_quickstart.py
• Jedis: SearchQuickstartExample.java
• Reference: Query Dialects