package lmdb

A transaction handle. A transaction may be read-only or read-write.

go ~rw db f makes a transaction in db with the permission rw and using the function f.

The function f will receive the transaction handle. All the operations called using the Txn module will be executed when f returns. The transaction handle should not be leaked outside of f.

Return None if the transaction was aborted with abort, and Some v otherwise.

Here is an example incrementing a value atomically:

go ~rw:`Write db begin fun txn ->
  let v = get k in
  put k (v+1) ;
  v
end

abort txn will abort the transaction.

get txn k returns the value associated to k.

• raises Not_found

  if the key is not in the database.

put txn k v associates the key k to the value v.

• parameter flags

  Flags that allow to modify the behavior of put.

append txn k v append k, v at the end of the database without performing comparisons.

Should only be used to quickly add already-sorted data to the database.

remove txn k removes k from the database.

If the database accepts duplicates:

• if elt is provided, only the specified binding is removed.
• if elt is not provided, all the bindings with k are removed.

The comparison function used by the database.