From: Jonathan Dieter Date: Mon, 19 Apr 2021 20:19:49 +0000 (+0100) Subject: Clean up phrasing to hopefully make it more clear that zdicts are optional X-Git-Tag: archive/raspbian/1.2.1+ds1-1+rpi1^2~7^2~7^2~4^2 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=617fef6e3263635140c635645e6a5bccf643b8c8;p=zchunk.git Clean up phrasing to hopefully make it more clear that zdicts are optional Signed-off-by: Jonathan Dieter --- diff --git a/README.md b/README.md index 9244aa4..3b9c360 100644 --- a/README.md +++ b/README.md @@ -53,10 +53,12 @@ zck_read_header ## Zchunk dictionaries -If you're creating a zchunk file that has any repetitive data, you may be -able to reduce the file size by using a [zstd dictionary](https://facebook.github.io/zstd/#small-data). -The dictionary is stored as extra data in chunk 0, but is used as a starting -point for compressing each chunk, which can give a significant overall savings. +By default, each chunk in a zchunk file is compressed independently. However, +if you're creating a zchunk file that has any repetitive data, you may +be able to reduce the overall file size by using a [zstd dictionary](https://facebook.github.io/zstd/#small-data). +The dictionary takes up extra space at the beginning of the zchunk file, but is +used as an identical initial dictionary for compressing each chunk, which can +give a significant overall savings. It is important that all further revisions of the zchunk file use the same dictionary. If the dictionary changes, none of the chunks will match from the