Re: [HACKERS] Contributing - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] Contributing
Date
Msg-id 29746.932485374@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] Contributing  (Thomas Lockhart <lockhart@alumni.caltech.edu>)
List pgsql-hackers
Thomas Lockhart <lockhart@alumni.caltech.edu> writes:
> The Hermit Hacker wrote:
>> Is this less then when using the -z option for CVS?

> I believe so. I'm just guessing at CVS's behavior, but I *know* that
> CVSup only sends compressed diffs of the changes to update a cvs
> repository or a checked-out tree. afaik CVS sends the entire file,
> compressing it for transmission much as does CVSup.

No, CVS will send either a whole file or a diff (the U or P code in its
printout tells you which way it updated the file, ie, Update whole thing
or Patch).  Either way, it's compressed if you've specified -z.

It looks like cvs has some semi-intelligent algorithm for choosing
which to do ... probably, it produces the diff and then looks to see
if the diff is bigger than the file.

I would expect CVSup to require more total net traffic just because
it has to transfer more info --- log entries, intermediate versions
(with CVS, if foo.c has been checked in three times since your last
update, you are sent one diff covering all the changes), etc.
I have not tried to time it however.  In any case, I suspect other
considerations are going to drive each hacker's choice of which way
to run.
        regards, tom lane


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