put duplicate

[cekvenich2]

Hi, I have a question on what happens on put when the key is duplicate.
I'm clear on what happens when dupSort is true.

But when it's false, and I do a put, it appends anyway.
(Should I always check for a put with a get to avoid collision?)
tia

[kriszyp]

Doing a put with dupSort: false with an entry that already exists will replace it. So:

db = open(...); // no dupSort
db.put('key', 'first value');
db.put('key', 'second value'); // replaces the value for 'key'
await db;
db.get('key'); // returns 'second value' 

LMDB does have an option for doing puts that will only execute if there is no existing entry and fail if there is an existing entry:

db.put('key', 'second value', { noOverwrite: true });
// or
db.ifNoExists('key', () => db.put('key', 'second value'));

Both of these will (return a promise that) resolves to false if there is already an existing entry.

[cekvenich2]

Thx. Whatever issue I had I now can't reproduce.