Compaction fails

[csterritt]

Hi -- really liking medea so far, in spite of the mythological allusions :-)

I'm writing some simple example code, first to create some entries, next to list some, and finally to delete some entries.

I was surprised to see that if I delete a key 'foo', then the next time I list all the keys it's there, with a value of 'undefined'. Is this expected behavior?

So I thought I'd try compacting the database after deleting a key, and got the following error:

% node delete_some_entries.js
Key 'foo' removed.
Error on medea compact: { Error: EBADF: bad file descriptor, fsync
    at Error (native) errno: -9, code: 'EBADF', syscall: 'fsync' }
Compact done.

This is using node v6.2.0 on OS X El Capitan.

Thanks!

[csterritt]

Update: I thought I'd try removing the db.compact call from the code which does the deletes, and put it in its own file.

I deleted the storage directory contents, re-created the data, and ran:

% node compact_db.js
Compact done.
% node list_entries.js
Key 'foo' has val undefined (?)
Key 'bar' has val 'bar_value'
Key 'baz' has val 'baz_value'

So no error (yay!) but I still see that the key deleted ('foo') is still in the list of keys. Is this expected behavior?

Thanks!

[kevinswiber]

Hey, @csterritt! Having no error and a value of undefined is the equivalent of a "Not Found." You can see how medeadown handles it here: https://github.com/medea/medeadown/blob/master/medeadown.js#L122

[csterritt]

Hey @kevinswiber thanks for the reply!

I guess I assumed that database compaction would remove a key with no value. Nope?

[rijnhard]

I'd also like to know the answer to this.
Compactions should remove deleted keys (the equivalent of an AOF rewrite)