LMDB API

OpenLDAP Lightning Memory-Mapped Database Manager. More...

Collaboration diagram for LMDB API:

Topics
	Version Macros
	Environment Flags
	Database Flags
	Write Flags

Classes
struct	MDB_val
	Generic structure used for passing keys and data in and out of the database. More...

Typedefs
typedef struct MDB_env	MDB_env
	Opaque structure for a database environment.
typedef struct MDB_txn	MDB_txn
	Opaque structure for a transaction handle.
typedef unsigned int	MDB_dbi
	A handle for an individual database in the DB environment.
typedef struct MDB_cursor	MDB_cursor
	Opaque structure for navigating through a database.
typedef struct MDB_val	MDB_val
	Generic structure used for passing keys and data in and out of the database.
typedef int	MDB_cmp_func(const MDB_val *a, const MDB_val *b)
	A callback function used to compare two keys in a database.
typedef void	MDB_rel_func(MDB_val *item, void *oldptr, void *newptr, void *relctx)
	A callback function used to relocate a position-dependent data item in a fixed-address database.

Detailed Description

OpenLDAP Lightning Memory-Mapped Database Manager.

Typedef Documentation

MDB_cmp_func

typedef int MDB_cmp_func(const MDB_val *a, const MDB_val *b)

A callback function used to compare two keys in a database.

MDB_cursor

typedef struct MDB_cursor MDB_cursor

Opaque structure for navigating through a database.

MDB_dbi

typedef unsigned int MDB_dbi

A handle for an individual database in the DB environment.

MDB_env

typedef struct MDB_env MDB_env

Opaque structure for a database environment.

A DB environment supports multiple databases, all residing in the same shared-memory map.

MDB_rel_func

typedef void MDB_rel_func(MDB_val *item, void *oldptr, void *newptr, void *relctx)

A callback function used to relocate a position-dependent data item in a fixed-address database.

The newptr gives the item's desired address in the memory map, and oldptr gives its previous address. The item's actual data resides at the address in item. This callback is expected to walk through the fields of the record in item and modify any values based at the oldptr address to be relative to the newptr address.

Parameters

[in,out]	item	The item that is to be relocated.
[in]	oldptr	The previous address.
[in]	newptr	The new address to relocate to.
[in]	relctx	An application-provided context, set by mdb_set_relctx().

Todo

This feature is currently unimplemented.

MDB_txn

typedef struct MDB_txn MDB_txn

Opaque structure for a transaction handle.

All database operations require a transaction handle. Transactions may be read-only or read-write.

MDB_val

typedef struct MDB_val MDB_val

Generic structure used for passing keys and data in and out of the database.

Values returned from the database are valid only until a subsequent update operation, or the end of the transaction. Do not modify or free them, they commonly point into the database itself.

Key sizes must be between 1 and mdb_env_get_maxkeysize() inclusive. The same applies to data sizes in databases with the MDB_DUPSORT flag. Other data items can in theory be from 0 to 0xffffffff bytes long.