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MTBL(7)   MTBL(7)


mtbl - immutable sorted string library


#include <mtbl.h>

gcc [flags] files -lmtbl [libraries]


The mtbl library provides interfaces for creating, searching, and merging Sorted String Table (SSTable) files in the MTBL format, which provide an immutable mapping of keys to values. Sorted String Tables are compact and provide fast random access to keys and key ranges. Keys and values are arbitrary byte arrays, and MTBL SSTables may not contain duplicate keys.

The six main interfaces provided by the mtbl library are:


Iterator objects provide a consistent interface for iterating over the key-value entries returned by other interfaces.


Source objects provide functions for obtaining iterators from an underlying data source. The mtbl_reader and mtbl_merger interfaces provide functions for obtaining references to a source object. The source methods return an mtbl_iter object.


Reader objects provide read-only access to MTBL files.


Writer objects initialize a new MTBL file from a sequence of key-value entries provided by the caller. Keys must be in sorted order based on lexicographical byte value, and keys may not be duplicated.


Merger objects receive multiple sequences of key-value entries from one or more mtbl_source objects and combine them into a single, sorted sequence. The combined, merged output sequence is provided via the mtbl_source interface.


Sorter objects receive a sequence of key-value entries provided by the caller and return them in sorted order. The caller must provide a callback function to merge values in the case of entries with duplicate keys. The sorted output sequence may be retrieved via the mtbl_iter interface or be dumped to an mtbl_writer object.


Fileset objects automatically maintain an mtbl_source built on top of the mtbl_merger and mtbl_reader interfaces. The set of underlying mtbl_reader objects is kept synchronized with a "setfile" on disk listing MTBL files.

Additionally, several utility interfaces are provided:


Calculates the CRC32C checksum of a byte array.


Functions for fixed-width encoding and decoding of 32 and 64 bit integers.


Functions for varint encoding and decoding of 32 and 64 bit integers.