Get By Predicate

Retrieve one or more stored vectors and their associated metadata from a store by applying a predicate filter. Unlike Get Key, which retrieves a single item by its unique key, Get by Predicate allows querying based on conditions defined on metadata fields (for example, "all items where category = book"). This is useful for flexible filtering, targeted queries, or conditional retrieval.

Source Code Example

Click to expand

use ahnlich_client_rs::db::DbClient;
use ahnlich_types::{
    db::query::GetPred,
    metadata::{MetadataValue, metadata_value::Value},
    predicates::{
        Predicate, PredicateCondition,
        predicate::Kind as PredicateKind,
        predicate_condition::Kind as PredicateConditionKind,
        Equals,
    },
};
use tokio;


#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let addr = "http://127.0.0.1:1369";
    let client = DbClient::new(addr.to_string()).await?;


    let condition = PredicateCondition {
        kind: Some(PredicateConditionKind::Value(Predicate {
            kind: Some(PredicateKind::Equals(Equals {
                key: "role".into(),
                value: Some(MetadataValue {
                    value: Some(Value::RawString("admin".into())),
                }),
            })),
        })),
    };


    let get_pred_params = GetPred {
        store: "Main".to_string(),
        condition: Some(condition),
    };


    let result = client.get_pred(get_pred_params, None).await?;
    println!("Fetched rows: {:#?}", result);


    Ok(())
}

Parameters

• params: GetPred — Contains the store name and predicate condition used to filter results.

• tracing_id: Option<String> — Optional trace context for observability, attached to the request if provided.

Returns

• Get — Response with all matched vectors and metadata.

• AhnlichError — Error if the store is missing, the predicate is invalid, or the server cannot complete the request.

Behavior

• Builds a gRPC request from the given GetPred parameters.

• Attaches optional tracing metadata using add_trace_parent.

• Calls the get_pred RPC on the server through the cloned client.

• Waits asynchronously for the server’s response and extracts the inner Get payload with .into_inner().