federicoceratto/nim-lmdb

Nim LMDB wrapper

Nim LMDB

Nim wrapper for the Symas LMDB library

"…​with only 32KB of object code, LMDB may seem tiny. But it’s the right 32KB." - from the LMDB home page.

More documentation: upstream docs - wikipedia page - exploring LMDB

Features

• Lightweight and ultra fast

• nim doc documentation

• Basic functional tests and benchmarks

• Tested on Linux

Usage

# Development library:
nimble install lmdb

# Runtime dependency:
sudo apt-get install liblmdb0

import lmdb

# create dbenv, transaction and a dbi
let dbenv = newLMDBEnv("./testdb")
let txn = dbenv.newTxn()
let dbi = txn.dbiOpen(nil, 0)

txn.put(dbi, "foo", "value")
let g = txn.get(dbi, "foo")
txn.del(dbi, "foo", "value")

# commit or abort transaction
txn.commit() # or txn.abort()

# close dbi and env
dbenv.close(dbi)
dbenv.envClose()

Also see tests/functional.nim for more examples.

Contributing

Testing and PRs are welcome.

nim-lmdb's Issues

[Question] how to get (unknown) keys of named DB

Hi,
Thanks for the library. I'm thinking this will be a big speed-up for my applications, but i'm having trouble making use of it.
I'm not seeing a proc for getting all keys of a named DB, so i'm guessing i need to get the count of key/value pairs using:

let c = txn.cursorOpen(dbi)
let key_count = c.count()

then, get the keys with something like this:

while i <= count:
  if i == 1:
    key = c.get("", op = FIRST)
  else:
    key = c.get("", op = NEXT)

  echo key

the empty string are to be a wild attempt at stumbling upon the answer via error message, as i don't see an example with anything besides a hard coded string. Also, I don't understand why the cursor needs a key to be specified to move through keys (using FIRST and NEXT) anyways.

when i try to use count(), it says the DB is not compat. so, i try to add DUPSORT to the DB and it complains that my flags have changed. I try to delete and recreate the DB, but i can't find the syntax for adding more than one dbflag when creating a new DB. I'm thinking i need DUPSORT and CREATE.

I've been at this longer than i care to admit, so any help is appreciated.

Thanks

Doc looks weird

Hi @FedericoCeratto just a heads up, documentation for this package looks weird: