From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 13 Jan 2021 08:54:52 GMT
Subject: Re: [PATCH 01/20] pack-revindex: introduce a new API
Message-ID: <xmqqv9c1xllv.fsf@gitster.c.googlers.com>
In-Reply-To: <xmqqa6tdz2fo.fsf@gitster.c.googlers.com>

Junio C Hamano <gitster@pobox.com> writes:

> Without knowing what exactly "pack position", "offset" and "index
> position" refer to, the above three are almost impossible to grok.
> Can we have one paragraph description for each?  Something along the
> lines of...
>
>  - Pack position: a packstream consists of series of byte ranges,
>    each of which represents an object, so the objects can be
>    numbered from 0 (the object whose data is stored at the earliest
>    part in the packfile) to N (the object whose data is stored at
>    the tail end of the packfile).  The number corresponding to an
>    object in this order in the packfile is called the "pack
>    position" of the object.
>
>  - Offset: The ofs_t distance between the beginning of a pack stream
>    and the beginning of data that represents an object is called the
>    "offset" of the object in the packfile.
>
>  - Index position: for a single pack stream, there is a table that
>    maps object name to its offset and the entries in this table are
>    sorted by the object name (this is what pack ".idx" file is).
>    The location (counting from 0) of an object in this table is
>    called the "index position" of the object in the packfile.
>
> I am not sure if the above correctly reflects what you meant by
> "position", though.

Please scratch the above.  I see Peff already pointed out pretty
much the same, and his phrasing looked a lot cleaner than my
attempt.

Thanks.