Need a method remove all keys but keep the file size not changed

[calvin2021y]

This is not a bug report but a future request.

I need a method to remove all keys, but not trim and truncate file size to DEFAULT_MMAP_SIZE.

any suggestions how to do it myself, or MMKV will consider add this future?

[calvin2021y]

I need reuse the db instance without close it. keep the file size to reduce the IO overhead.

[lingol]

What do you mean by saying reduce IO overhead? Do you find MMKV's space expansion algorithm not working for you?

[calvin2021y]

The file size reduced into 4KB after clear.

I use 2 MMKV instance as log rotate at high speed, after one full then change to other one.

In this case every time rotate the file size changed, I guess keep the file size not change but destroy the data inside it will avoid a lot system call and block time.

[lingol]

Why do you need two instances and rotate them? It's quite a strange usage.

[calvin2021y]

1. avoid thread lock, the log always read/write in one thread

2. if I need destroy one, no need search by key range

3. when need backup or send to remote, just move the task into other thread.

[lingol]

I take it that you have set a size limit or key count limit per instance. How large is one file grow to, normally speaking?

[calvin2021y]

Yes, I use count limit. the file size could be 10M to 100M depend the logs item size and MAX_LOG_ENTRY_LIMIT(adjustable).