Struct libmdbx::Cursor

pub struct Cursor<'txn, K>where
    K: TransactionKind,{ /* private fields */ }

A cursor for navigating the items within a table.

Implementations

impl<'txn, K> Cursor<'txn, K>where
    K: TransactionKind,

pub fn cursor(&self) -> *mut MDBX_cursor

Returns a raw pointer to the underlying MDBX cursor.

The caller must ensure that the pointer is not used after the lifetime of the cursor.

pub fn first<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at first key/data item.

pub fn first_dup<Value>(&mut self) -> Result<Option<Value>>where
    Value: TableObject<'txn>,

TableFlags::DUP_SORT-only: Position at first data item of current key.

pub fn get_both<Value>(&mut self, k: &[u8], v: &[u8]) -> Result<Option<Value>>where
    Value: TableObject<'txn>,

TableFlags::DUP_SORT-only: Position at key/data pair.

pub fn get_both_range<Value>(
    &mut self,
    k: &[u8],
    v: &[u8]
) -> Result<Option<Value>>where
    Value: TableObject<'txn>,

TableFlags::DUP_SORT-only: Position at given key and at first data greater than or equal to specified data.

pub fn get_current<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Return key/data at current cursor position.

pub fn get_multiple<Value>(&mut self) -> Result<Option<Value>>where
    Value: TableObject<'txn>,

DupFixed-only: Return up to a page of duplicate data items from current cursor position. Move cursor to prepare for Self::next_multiple().

pub fn last<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at last key/data item.

pub fn last_dup<Value>(&mut self) -> Result<Option<Value>>where
    Value: TableObject<'txn>,

DupSort-only: Position at last data item of current key.

pub fn next<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at next data item

pub fn next_dup<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

TableFlags::DUP_SORT-only: Position at next data item of current key.

pub fn next_multiple<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

TableFlags::DUP_FIXED-only: Return up to a page of duplicate data items from next cursor position. Move cursor to prepare for MDBX_NEXT_MULTIPLE.

pub fn next_nodup<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at first data item of next key.

pub fn prev<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at previous data item.

pub fn prev_dup<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

TableFlags::DUP_SORT-only: Position at previous data item of current key.

pub fn prev_nodup<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at last data item of previous key.

pub fn set<Value>(&mut self, key: &[u8]) -> Result<Option<Value>>where
    Value: TableObject<'txn>,

Position at specified key.

pub fn set_key<Key, Value>(&mut self, key: &[u8]) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at specified key, return both key and data.

pub fn set_range<Key, Value>(
    &mut self,
    key: &[u8]
) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at first key greater than or equal to specified key.

pub fn prev_multiple<Key, Value>(&mut self) -> Result<Option<(Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

TableFlags::DUP_FIXED-only: Position at previous page and return up to a page of duplicate data items.

pub fn set_lowerbound<Key, Value>(
    &mut self,
    key: &[u8]
) -> Result<Option<(bool, Key, Value)>>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Position at first key-value pair greater than or equal to specified, return both key and data, and the return code depends on a exact match.

For non DupSort-ed collections this works the same as Self::set_range(), but returns false if key found exactly and true if greater key was found.

For DupSort-ed a data value is taken into account for duplicates, i.e. for a pairs/tuples of a key and an each data value of duplicates. Returns false if key-value pair found exactly and true if the next pair was returned.

pub fn iter<Key, Value>(&mut self) -> Iter<'txn, '_, K, Key, Value> where
    Self: Sized,
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over table items. The iterator will begin with item next after the cursor, and continue until the end of the table. For new cursors, the iterator will begin with the first item in the table.

For tables with duplicate data items (TableFlags::DUP_SORT), the duplicate data items of each key will be returned before moving on to the next key.

pub fn iter_start<Key, Value>(&mut self) -> Iter<'txn, '_, K, Key, Value> where
    Self: Sized,
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over table items starting from the beginning of the table.

For tables with duplicate data items (TableFlags::DUP_SORT), the duplicate data items of each key will be returned before moving on to the next key.

pub fn into_iter_start<Key, Value>(self) -> IntoIter<'txn, K, Key, Value>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over table items starting from the beginning of the table.

For tables with duplicate data items (TableFlags::DUP_SORT), the duplicate data items of each key will be returned before moving on to the next key.

pub fn iter_from<Key, Value>(
    &mut self,
    key: &[u8]
) -> Iter<'txn, '_, K, Key, Value> where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over table items starting from the given key.

For tables with duplicate data items (TableFlags::DUP_SORT), the duplicate data items of each key will be returned before moving on to the next key.

pub fn into_iter_from<Key, Value>(
    self,
    key: &[u8]
) -> IntoIter<'txn, K, Key, Value>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over table items starting from the given key.

For tables with duplicate data items (TableFlags::DUP_SORT), the duplicate data items of each key will be returned before moving on to the next key.

pub fn iter_dup<Key, Value>(&mut self) -> IterDup<'txn, '_, K, Key, Value> where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over duplicate table items. The iterator will begin with the item next after the cursor, and continue until the end of the table. Each item will be returned as an iterator of its duplicates.

pub fn iter_dup_start<Key, Value>(&mut self) -> IterDup<'txn, '_, K, Key, Value> where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over duplicate table items starting from the beginning of the table. Each item will be returned as an iterator of its duplicates.

pub fn iter_dup_from<Key, Value>(
    &mut self,
    key: &[u8]
) -> IterDup<'txn, '_, K, Key, Value> where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over duplicate items in the table starting from the given key. Each item will be returned as an iterator of its duplicates.

pub fn iter_dup_of<Key, Value>(
    &mut self,
    key: &[u8]
) -> Iter<'txn, '_, K, Key, Value> where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over the duplicates of the item in the table with the given key.

pub fn into_iter_dup_of<Key, Value>(
    self,
    key: &[u8]
) -> IntoIter<'txn, K, Key, Value>where
    Key: TableObject<'txn>,
    Value: TableObject<'txn>,

Iterate over the duplicates of the item in the table with the given key.

impl<'txn> Cursor<'txn, RW>

pub fn put(&mut self, key: &[u8], data: &[u8], flags: WriteFlags) -> Result<()>

Puts a key/data pair into the table. The cursor will be positioned at the new data item, or on failure usually near it.

pub fn del(&mut self, flags: WriteFlags) -> Result<()>

Deletes the current key/data pair.

Flags

WriteFlags::NO_DUP_DATA may be used to delete all data items for the current key, if the table was opened with TableFlags::DUP_SORT.

Trait Implementations

impl<'txn, K> Clone for Cursor<'txn, K>where
    K: TransactionKind,

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'txn, K> Debug for Cursor<'txn, K>where
    K: TransactionKind,

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

Formats the value using the given formatter.

impl<'txn, K> Drop for Cursor<'txn, K>where
    K: TransactionKind,

fn drop(&mut self)

Executes the destructor for this type.

impl<'txn, K> IntoIterator for Cursor<'txn, K>where
    K: TransactionKind,

type Item = Result<(Cow<'txn, [u8]>, Cow<'txn, [u8]>), Error>

The type of the elements being iterated over.

type IntoIter = IntoIter<'txn, K, Cow<'txn, [u8]>, Cow<'txn, [u8]>>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'txn, K> Send for Cursor<'txn, K>where
    K: TransactionKind,

impl<'txn, K> Sync for Cursor<'txn, K>where
    K: TransactionKind,