Delete By Predicate

Removes one or more records from a store based on a predicate condition. Instead of targeting records by key, this operation evaluates a logical filter against stored metadata or values and deletes all matching entries. It provides a flexible way to bulk-remove records without knowing their exact keys.

Source Code Example

Click to expand

use ahnlich_types::db::query::DelPred;
use ahnlich_types::db::server::Del;
use ahnlich_types::predicates::{Predicate, PredicateCondition, predicate::Kind as PredicateKind, predicate_condition::Kind as PredicateConditionKind};
use ahnlich_client_rs::db::DbClient;
use ahnlich_types::metadata::{MetadataValue, metadata_value::Value};
use std::collections::HashMap;


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


    // Define the predicate condition to delete
    let condition = PredicateCondition {
        kind: Some(PredicateConditionKind::Value(Predicate {
            kind: Some(PredicateKind::Equals(ahnlich_types::predicates::Equals {
                key: "medal".into(),
                value: Some(MetadataValue {
                    value: Some(Value::RawString("gold".into())),
                }),
            })),
        })),
    };


    // Parameters for deleting predicate
    let params = DelPred {
        store: "Main".to_string(), // your store name
        condition: Some(condition),
    };


    // Call delete predicate
    match db_client.del_pred(params, None).await {
        Ok(Del { deleted_count }) => {
            println!("Successfully deleted {} predicate(s).", deleted_count);
        }
        Err(e) => {
            eprintln!("Error deleting predicate: {:?}", e);
        }
    }


    Ok(())
}

Parameters

• params: DelPred — Defines the predicate filter used to match records for deletion.

• tracing_id: Option<String> — Optional trace identifier for monitoring and observability.

Returns

• Del — Confirmation of the deletion request, including details of what was removed.

• AhnlichError — If the predicate is invalid or no matching records are found.

Behavior

• Wraps the predicate parameters in a request object.

• Propagates tracing context if available.

• Executes the delete operation against the DB service.

• Returns confirmation once the matching records are deleted.