Iterator Class

Definition

public class Iterator : IDisposable

Iterator is an ordered cursor over a database or a single column family. Because RocksDB stores keys in sorted byte order, an iterator is the primitive for range scans, prefix scans, and reverse scans.

Remarks

Create an iterator with RocksDb.NewIterator. It holds a native handle and an implicit snapshot of the database state at construction time, so concurrent writes are invisible to it. Always dispose the iterator (or wrap it in using) — a long-lived iterator pins obsolete SST files and blocks compaction.

Scope a scan efficiently by setting iterate_lower_bound / iterate_upper_bound on ReadOptions, or pin an older view with a snapshot. On net6+, GetKeySpan / GetValueSpan give zero-allocation access to the native buffers. See Iterators.

Methods

SeekToFirst

public Iterator SeekToFirst()

Positions the iterator at the smallest key.

SeekToLast

public Iterator SeekToLast()

Positions the iterator at the largest key.

Seek

public Iterator Seek(string key)

Positions the iterator at the first key greater than or equal to key.

SeekForPrev

public Iterator SeekForPrev(string key)

Positions the iterator at the last key less than or equal to key.

Next

public Iterator Next()

Moves the iterator forward by one key.

Prev

public Iterator Prev()

Moves the iterator backward by one key. Combine with SeekToLast for descending iteration.

Valid

public bool Valid()

Returns whether the iterator is currently positioned on a valid entry. Use it as the loop condition.

StringKey

public string StringKey()

Returns the current key decoded as a UTF-8 string.

StringValue

public string StringValue()

Returns the current value decoded as a UTF-8 string.

GetKeySpan

public ReadOnlySpan<byte> GetKeySpan()

Returns the current key as a zero-allocation ReadOnlySpan<byte> over the native buffer (net6+). The span is only valid until the next move.

GetValueSpan

public ReadOnlySpan<byte> GetValueSpan()

Returns the current value as a zero-allocation ReadOnlySpan<byte> over the native buffer (net6+). The span is only valid until the next move.

Applies to