in reply to mldbm file size limit?

jling,
By default, MLDBM uses SDBM which has the following warning from TFM:

There are a number of limits on the size of the data that you can store in the SDBM file. The most important is that the length of a key, plus the length of its associated value, may not exceed 1008 bytes.

You will need to give a snippet of code that demonstrates the problem if you are not using the defaults so that we can investigate further.

Cheers - L~R