This module allows OpenResty applications to use the LMDB (Lightning Memory-Mapped Database) inside the Nginx worker process. It has two parts, a core module built into Nginx that controls the life cycle of the database environment, and a FFI based Lua binding for interacting with the module to access/change data.
syntax: value, err = lmdb.get(key, db?)
context: any context except init_by_lua*
Gets the value corresponding to key from LMDB database db. If db is omitted,
it defaults to "_default".
If the key does not exist, nil will be returned.
In case of error, nil and a string describing the error will be returned instead.
syntax: ok, err = lmdb.set(key, value, db?)
context: any context except init_by_lua*
Sets the value corresponding to key to value inside LMDB database db. If db is omitted,
it defaults to "_default".
Setting a key's value to nil will remove that key from the corresponding database.
In case of error, nil and a string describing the error will be returned instead.
syntax: status, err = lmdb.get_env_info()
context: any context except init_by_lua*
Get the LMDB database runtime information. status table struct as below.
{
"last_used_page": 11,
"last_txnid": 14,
"max_readers": 126,
"num_readers": 1,
"map_size": 1048576,
"page_size": 4096,
"max_map_size": 1048576
}
In case of error, nil and a string describing the error will be returned instead.
syntax: ok, err = lmdb.db_drop(delele?, db?)
context: any context except init_by_lua*
Clears the contents of database db. If delete is true, then the database handle is also dropped.
In case of error, nil and a string describing the error will be returned instead.
syntax: local txn = transaction.begin(hint?)
context: any context
Creates a new LMDB transaction object. This does not actually starts the transaction, but only creates
a Lua table that stores the operations for execution later. If hint is provided then the Lua table holding
the operations will be pre-allocated to store hint operations.
syntax: txn:reset()
context: any context
Resets a transaction object. Removes all existing transactions and results (if any) from the object but
keeps the table's capacity. After this call the transaction can be reused as if it was a new transaction
returned by transaction.begin().
syntax: txn:get(key, db?)
context: any context
Appends a get operation in the transactions table. If db is omitted,
it defaults to "_default". The output table contains the following
fields:
value: Value forkey, ornilifkeyis not found
syntax: txn:set(key, value, db?)
context: any context
Appends a set operation in the transactions table. If db is omitted,
it defaults to "_default". The output able contains the following
fields:
result: Alwaystruefor successful transaction commits
syntax: txn:db_open(create, db?)
context: any context
Appends a db_open operation in the transactions table. If db is omitted,
it defaults to "_default". This operation does not return anything
in case of successful transaction commits.
syntax: txn:db_drop(delete, db?)
context: any context
Appends a db_drop operation in the transactions table. If db is omitted,
it defaults to "_default". This operation does not return anything
in case of successful transaction commits.
syntax: local res, err = txn:commit()
context: any context except init_by_lua*
Commits all operations currently inside the transactions table using a single LMDB transaction. Since LMDB transaction exhibits ACID (atomicity, consistency, isolation, durability) properties, this method will either commit all operations at once or fail without causing side effects.
In case of successful transaction commit, true will be returned. Output value of each operation
can be accessed like this: txn[3].value. Please note that Lua table index starts at 1 and the
order corresponds to the order operations were appended into the transaction. So the first operation's
output will be inside txn[1] and second operation's result will be inside txn[2].
In case of any error during the transaction, it will be rolled back and nil and
an string describing the reason of the failure will be returned instead. Accessing the output value
from the txn table when commit() returned an error is undefined.
syntax: lmdb_environment_path path;
context: main
Set the directory in which the LMDB database files reside.
syntax: lmdb_max_databases number;
context: main
Set the maximum number of named databases, the default value is 1.
syntax: lmdb_map_size number;
context: main
Set the size of the memory map, the default value is 1048576(1MB).
syntax: lmdb_encryption_key path/to/keyfile;
context: main
Encrypt the lmdb database. Encryption is enabled only when the lmdb_encryption_key is set. The
content of keyfile will be used to derive a key to encrypt lmdb.
syntax: lmdb_encryption_mode "aes-256-gcm";
context: main
Set the lmdb database encryption mode. The default encryption mode is "aes-256-gcm". The optional encryption
modes are "chacha20-poly1305" and "aes-256-gcm". Note that lmdb_encryption_mode needs to be set only when
lmdb_encryption_key is set.
Copyright (c) 2021-2022 Kong, Inc.
Licensed under the Apache License, Version 2.0 <LICENSE or https://www.apache.org/licenses/LICENSE-2.0>. Files in the project may not be copied, modified, or distributed except according to those terms.