3500, 1024, 767 - Maximum Key Length for InnoDB

[Bambarbia Kirkudu]

It's written in docs that internal maximum key length for InnoDB indexes is 3500 byte, and limited by MySQL to 1024 bytes. In real-life it is limited to 767 bytes.

How to increase MySQL limitations up to 3500?

Just as a sample of use case: I need database of unique URLs, and Internet Explorer has limitation 2048 byte. Of course I am using ascii-fields, and I can even gzip long URLs or encode it somehow. Don't want to spend a time with compiling from source; and can't expect that requirements won't change over time.

May be different storage engine for this specific table? Short MD5 hash-codes for VARCHAR(2048) and programmatic sub-scans without unique indexes?

Thanks