Re: lztext and compression ratios...

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jan Wieck <JanWieck(at)yahoo(dot)com>
Cc: PostgreSQL GENERAL <pgsql-general(at)postgresql(dot)org>, PostgreSQL HACKERS <pgsql-hackers(at)postgresql(dot)org>, PostgreSQL SQL <pgsql-sql(at)postgresql(dot)org>
Subject: Re: lztext and compression ratios...
Date: 2000-07-06 14:22:55
Message-ID: 29094.962893375@sss.pgh.pa.us
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JanWieck(at)t-online(dot)de (Jan Wieck) writes:
>> As long as you brought it up: how sure are you that the method you've
>> used is not subject to any patents?

> Now that you ask for it: I'm not sure. Could be.

>> If you can show that this method uses no ideas not found in zlib,
>> then I'll feel reassured

> To do so I don't know enough about the algorithms used in
> zlib. Is there someone out here who could verify that if I
> detailed enough describe what our compression code does?

After a quick look at the code, I don't think there is anything
problematic about the data representation or the decompression
algorithm. The compression algorithm is another story, and it's
not real well commented :-(. The important issues are how you
search for matches in the past text and how you decide which match
is the best one to use. Please update the code comments to describe
that, and I'll take another look.

regards, tom lane

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