LMDB bindings for lua

license: MIT

errors

operations that can fail will return nil, error, errno on failure.

functions

`lmdb.open(path, opt)`

create a new environment handle and open the database at the path. returns the environment handle (env) on success.

opt is an optional table of options:

maxdbs: number: the maximum number of databases in the environment. must be set if multiple databases will be used.
mapsize: number: the memory map size used for this environment. this is also the maximum size of the database. default: 1GiB (1024^3).
rdonly: boolean: open the environment in read-only mode.
nosubdir: boolean: the path is used for the database file itself and not its containing directory.
nosync: boolean: don't flush buffers to disk when committing.
nolock: boolean: turn off locking. the application must manage all concurrency.

`lmdb.version()`

returns the LMDB version as major, minor, patch.

`lmdb.next(db, key)`

returns the next key-value pair after key in the database handle db, or the first key-value pair if key is nil. keys are ordered lexicographically. unlike next, this function does not work for traversal if, during traversal, keys are set to nil. (TODO: fix this somehow)

`env:txn_begin(write_enabled)`

create a new transaction in the environment. if write_enabled is true, then the transaction may make modifications to the database. returns the transaction handle (txn) on success.

`env:copy(path)`

copy the environment to the specified path. return true on success.

`env:sync(force)`

flush buffers to disk. if force is true, a synchronous flush is performed even if nosync is set. return true on success.

`env:close()`

close the environment.

`txn:open(name, create)`

open a database in the environment. if multiple databases are to be used in the environment, name is the name of the database to open. otherwise, it should not be supplied. if create is true, the database is created if it does not exist. returns a database handle (db) on success.

`txn:drop(name)`

delete the database name from the environment. (or clear the database, if name is not supplied)

`txn:abort()`

abandon all operations performed in the transaction.

`txn:commit()`

commit all operations of the transaction into the database.

`txn:txn_begin()`

create a nested transaction in the parent transaction.

`db[key]`

read the value of key from the database.

`db[key] = value`

write value as the value of key into the database.

`pairs(db)`, `lmdb.pairs(db)`

returns lmdb.next, db, nil, allowing iteration through all the key-value pairs of a database. the lmdb.pairs form works even on lua 5.1, which doesn't support the __pairs metamethod.

`#db`

return the number of entries in the database.