Struct Connection 

pub struct Connection<'a> { /* private fields */ }

Connections are used to interact with a Database instance.

Concurrency

Each connection is thread-safe, and multiple connections can connect to the same Database instance in a multithreaded environment.

Note that since connections require a reference to the Database, creating or using connections in multiple threads cannot be done from a regular std::thread since the threads (and connections) could outlive the database. This can be worked around by using a scoped thread (Note: Introduced in rust 1.63. For compatibility with older versions of rust, crosssbeam_utils::thread::scope can be used instead).

Also note that write queries can only be done one at a time; the query command will return an error if another write query is in progress.

let conn = Connection::new(&db)?;
conn.query("CREATE NODE TABLE Person(name STRING, age INT32, PRIMARY KEY(name));")?;
// Write queries must be done sequentially
conn.query("CREATE (:Person {name: 'Alice', age: 25});")?;
conn.query("CREATE (:Person {name: 'Bob', age: 30});")?;
let (alice, bob) = std::thread::scope(|s| -> Result<(Vec<Value>, Vec<Value>), Error> {
    let alice_thread = s.spawn(|| -> Result<Vec<Value>, Error> {
        let conn = Connection::new(&db)?;
        let mut result = conn.query("MATCH (a:Person) WHERE a.name = \"Alice\" RETURN a.name AS NAME, a.age AS AGE;")?;
        Ok(result.next().unwrap())
    });
    let bob_thread = s.spawn(|| -> Result<Vec<Value>, Error> {
        let conn = Connection::new(&db)?;
        let mut result = conn.query(
            "MATCH (a:Person) WHERE a.name = \"Bob\" RETURN a.name AS NAME, a.age AS AGE;",
        )?;
        Ok(result.next().unwrap())
    });
    Ok((alice_thread.join().unwrap()?, bob_thread.join().unwrap()?))
 })?;

 assert_eq!(alice, vec!["Alice".into(), 25.into()]);
 assert_eq!(bob, vec!["Bob".into(), 30.into()]);
 temp_dir.close()?;
 Ok(())

Implementations

impl<'a> Connection<'a>

pub fn new(database: &'a Database) -> Result<Self, Error>

Creates a connection to the database.

Arguments

• database: A reference to the database instance to which this connection will be connected.

pub fn set_max_num_threads_for_exec(&mut self, num_threads: u64)

Sets the maximum number of threads to use for execution in the current connection

Arguments

• num_threads: The maximum number of threads to use for execution in the current connection

pub fn get_max_num_threads_for_exec(&self) -> u64

Returns the maximum number of threads used for execution in the current connection

pub fn prepare(&self, query: &str) -> Result<PreparedStatement, Error>

Prepares the given query and returns the prepared statement. PreparedStatements can be run using Connection::execute

Arguments

• query: The query to prepare. See https://kuzudb.com/docs/cypher for details on the query format.

pub fn query(&self, query: &str) -> Result<QueryResult<'a>, Error>

Executes the given query and returns the result.

Arguments

• query: The query to execute. See https://kuzudb.com/docs/cypher for details on the query format.

pub fn execute( &self, prepared_statement: &mut PreparedStatement, params: Vec<(&str, Value)>, ) -> Result<QueryResult<'a>, Error>

Executes the given prepared statement with args and returns the result.

Arguments

• prepared_statement: The prepared statement to execute

 let conn = Connection::new(&db)?;
 conn.query("CREATE NODE TABLE Person(name STRING, age INT64, PRIMARY KEY(name));")?;
 let mut prepared = conn.prepare("CREATE (:Person {name: $name, age: $age});")?;
 conn.execute(&mut prepared,
     vec![("name", Value::String("Alice".to_string())), ("age", Value::Int64(25))])?;
 conn.execute(&mut prepared,
     vec![("name", Value::String("Bob".to_string())), ("age", Value::Int64(30))])?;

pub fn interrupt(&self) -> Result<(), Error>

Interrupts all queries currently executing within this connection

pub fn set_query_timeout(&self, timeout_ms: u64)

Sets the query timeout value of the current connection

A value of zero (the default) disables the timeout.

Trait Implementations

impl Send for Connection<'_>

impl Sync for Connection<'_>