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Published 20 hours ago • verified publisher icon conor42

Why is large dictionary size no longer supported?

Open amstc opened this issue 4 years ago • 2 comments

v0.9.1 used to support 4GB dictionary. Why is the limit lowered to 1GB in both the later versions of Radyx and the new release of fast LZMA2 DLL?

amstc avatar Apr 13 '20 18:04 amstc

Mostly because I couldn't test very large dictionaries at the time, and also because the specification only allows 1.5 Gb, though some decoders may accept larger ones anyway. It will be able to support 1.5 Gb after some minor interface changes. This is already done in the fxz implementation.

conor42 avatar Apr 15 '20 06:04 conor42

Igor Pavlov once said something similar. https://sourceforge.net/p/sevenzip/discussion/45798/thread/0c997a36/

Maybe because of a lack market demand, it looks it is hard to find an software with large dictionaries supporting. So far I've found Radyx, fa011.zip and PowerArchiver, these three break the typical 2GB barrier. fa011.zip claims supporting dictionaries up to 4000MB (https://github.com/Bulat-Ziganshin/FA/blob/master/0.11/Release-notes.md). PowerArchiver provides an option up to 4095MB but its workable size seems no larger than 2048MB.

Large dictionary supporting is just uncommon, so I was not surprised when I found that the dictionary settings in Radyx was lowered from 4GB to 1GB. Anyway, the 1.5GB plan is a good news, and thanks for your development.

amstc avatar Apr 15 '20 10:04 amstc