Struct Database

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

Database

Implementations

impl<'a> Database<'a>

pub fn stat(&'a self) -> MdbResult<MDB_stat>

Retrieves current db’s statistics.

pub fn get<V: FromMdbValue + 'a>(&'a self, key: &dyn ToMdbValue) -> MdbResult<V>

Retrieves a value by key. In case of DbAllowDups it will be the first value

Examples found in repository

examples/simple.rs (line 32)

fn main() {
    let env = EnvBuilder::new().open("test-lmdb", 0o777).unwrap();

    let db_handle = env.get_default_db(DbFlags::empty()).unwrap();
    let txn = env.new_transaction().unwrap();
    {
        let db = txn.bind(&db_handle); // get a database bound to this transaction

        let pairs = vec![("Albert", "Einstein",),
                         ("Joe", "Smith",),
                         ("Jack", "Daniels")];

        for &(name, surname) in pairs.iter() {
            db.set(&surname, &name).unwrap();
        }
    }

    // Note: `commit` is choosen to be explicit as
    // in case of failure it is responsibility of
    // the client to handle the error
    match txn.commit() {
        Err(_) => panic!("failed to commit!"),
        Ok(_) => ()
    }

    let reader = env.get_reader().unwrap();
    let db = reader.bind(&db_handle);
    let name = db.get::<&str>(&"Smith").unwrap();
    println!("It's {} Smith", name);
}

pub fn set(&self, key: &dyn ToMdbValue, value: &dyn ToMdbValue) -> MdbResult<()>

Sets value for key. In case of DbAllowDups it will add a new item

Examples found in repository

examples/simple.rs (line 18)

fn main() {
    let env = EnvBuilder::new().open("test-lmdb", 0o777).unwrap();

    let db_handle = env.get_default_db(DbFlags::empty()).unwrap();
    let txn = env.new_transaction().unwrap();
    {
        let db = txn.bind(&db_handle); // get a database bound to this transaction

        let pairs = vec![("Albert", "Einstein",),
                         ("Joe", "Smith",),
                         ("Jack", "Daniels")];

        for &(name, surname) in pairs.iter() {
            db.set(&surname, &name).unwrap();
        }
    }

    // Note: `commit` is choosen to be explicit as
    // in case of failure it is responsibility of
    // the client to handle the error
    match txn.commit() {
        Err(_) => panic!("failed to commit!"),
        Ok(_) => ()
    }

    let reader = env.get_reader().unwrap();
    let db = reader.bind(&db_handle);
    let name = db.get::<&str>(&"Smith").unwrap();
    println!("It's {} Smith", name);
}

pub fn append<K: ToMdbValue, V: ToMdbValue>( &self, key: &K, value: &V, ) -> MdbResult<()>

Appends new key-value pair to database, starting a new page instead of splitting an existing one if necessary. Requires that key be >= all existing keys in the database (or will return KeyExists error).

pub fn append_duplicate<K: ToMdbValue, V: ToMdbValue>( &self, key: &K, value: &V, ) -> MdbResult<()>

Appends new value for the given key (requires DbAllowDups), starting a new page instead of splitting an existing one if necessary. Requires that value be >= all existing values for the given key (or will return KeyExists error).

pub fn insert( &self, key: &dyn ToMdbValue, value: &dyn ToMdbValue, ) -> MdbResult<()>

Set value for key. Fails if key already exists, even when duplicates are allowed.

pub fn del(&self, key: &dyn ToMdbValue) -> MdbResult<()>

Deletes value for key.

pub fn del_item( &self, key: &dyn ToMdbValue, data: &dyn ToMdbValue, ) -> MdbResult<()>

Should be used only with DbAllowDups. Deletes corresponding (key, value)

pub fn new_cursor(&'a self) -> MdbResult<Cursor<'a>>

Returns a new cursor

pub fn del_db(self) -> MdbResult<()>

Deletes current db, also moves it out

pub fn clear(&self) -> MdbResult<()>

Removes all key/values from db

pub fn iter(&'a self) -> MdbResult<CursorIterator<'a, CursorIter>>

Returns an iterator for all values in database

pub fn keyrange_from<'c, K: ToMdbValue>( &'c self, start_key: &'c K, ) -> MdbResult<CursorIterator<'c, CursorFromKeyIter<'_>>>

Returns an iterator through keys starting with start_key (>=), start_key is included

pub fn keyrange_to<'c, K: ToMdbValue + 'c>( &'c self, end_key: &'c K, ) -> MdbResult<CursorIterator<'c, CursorToKeyIter<'_>>>

Returns an iterator through keys less than end_key, end_key is not included

pub fn keyrange_from_to<'c, K: ToMdbValue + 'c>( &'c self, start_key: &'c K, end_key: &'c K, ) -> MdbResult<CursorIterator<'c, CursorKeyRangeIter<'_>>>

Returns an iterator through keys start_key <= x < end_key. This is, start_key is included in the iteration, while end_key is kept excluded.

pub fn keyrange<'c, K: ToMdbValue + 'c>( &'c self, start_key: &'c K, end_key: &'c K, ) -> MdbResult<CursorIterator<'c, CursorKeyRangeIter<'_>>>

Returns an iterator for values between start_key and end_key (included). Currently it works only for unique keys (i.e. it will skip multiple items when DB created with ffi::MDB_DUPSORT). Iterator is valid while cursor is valid

pub fn item_iter<'c, 'db: 'c, K: ToMdbValue>( &'db self, key: &'c K, ) -> MdbResult<CursorIterator<'c, CursorItemIter<'c>>>

Returns an iterator for all items (i.e. values with same key)

pub fn set_compare( &self, cmp_fn: extern "C" fn(*const MDB_val, *const MDB_val) -> c_int, ) -> MdbResult<()>

Sets the key compare function for this database.

Warning: This function must be called before any data access functions are used, otherwise data corruption may occur. The same comparison function must be used by every program accessing the database, every time the database is used.

If not called, keys are compared lexically, with shorter keys collating before longer keys.

Setting lasts for the lifetime of the underlying db handle.

pub fn set_dupsort( &self, cmp_fn: extern "C" fn(*const MDB_val, *const MDB_val) -> c_int, ) -> MdbResult<()>

Sets the value comparison function for values of the same key in this database.

Warning: This function must be called before any data access functions are used, otherwise data corruption may occur. The same dupsort function must be used by every program accessing the database, every time the database is used.

If not called, values are compared lexically, with shorter values collating before longer values.

Only used when DbAllowDups is true. Setting lasts for the lifetime of the underlying db handle.

Trait Implementations

impl<'a> Debug for Database<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.