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Re: Idle git question: how come so many "objects"?
So I just made a commit that touched four files in all six active branches, and I see: $ git push Counting objects: 172, done. Compressing objects: 100% (89/89), done. Writing objects: 100% (89/89), 17.07 KiB, done. Total 89 (delta 80), reused 0 (delta 0) To ssh://git(at)gitmaster(dot)postgresql(dot)org/postgresql.git 35a3def..8a6eb2e REL8_1_STABLE -> REL8_1_STABLE cfb6ac6..b0e2092 REL8_2_STABLE -> REL8_2_STABLE 301a822..0d45e8c REL8_3_STABLE -> REL8_3_STABLE 61f8618..6bd3753 REL8_4_STABLE -> REL8_4_STABLE 09425f8..0a85bb2 REL9_0_STABLE -> REL9_0_STABLE c0b5fac..225f0aa master -> master Now I realize that in addition to the four files there's a "tree" object and a "commit" object, but that still only adds up to 36 objects that should be created in this transaction. How does it get to 172? And then where do the 89 and 80 numbers come from? regards, tom lane
On Wed, Dec 01, 2010 at 01:03:26AM -0500, Tom Lane wrote: > So I just made a commit that touched four files in all six active > branches, and I see: > > $ git push > Counting objects: 172, done. > Compressing objects: 100% (89/89), done. > Writing objects: 100% (89/89), 17.07 KiB, done. > Total 89 (delta 80), reused 0 (delta 0) > To ssh://git(at)gitmaster(dot)postgresql(dot)org/postgresql.git > 35a3def..8a6eb2e REL8_1_STABLE -> REL8_1_STABLE > cfb6ac6..b0e2092 REL8_2_STABLE -> REL8_2_STABLE > 301a822..0d45e8c REL8_3_STABLE -> REL8_3_STABLE > 61f8618..6bd3753 REL8_4_STABLE -> REL8_4_STABLE > 09425f8..0a85bb2 REL9_0_STABLE -> REL9_0_STABLE > c0b5fac..225f0aa master -> master > > Now I realize that in addition to the four files there's a "tree" object > and a "commit" object, but that still only adds up to 36 objects that > should be created in this transaction. How does it get to 172? And > then where do the 89 and 80 numbers come from? IIRC, each directory also counts as an object. So if you change a file in a/b/c/d you get 5 commit objects, one for the file and four for the directories. What the delta is for I don't know. Perhaps some of the diffs were the same between branches and these got merged? Have a nice day, -- Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/ > Patriotism is when love of your own people comes first; nationalism, > when hate for people other than your own comes first. > - Charles de Gaulle
On Wed, Dec 1, 2010 at 2:08 AM, Martijn van Oosterhout
<kleptog(at)svana(dot)org> wrote:
> On Wed, Dec 01, 2010 at 01:03:26AM -0500, Tom Lane wrote:
>> So I just made a commit that touched four files in all six active
>> branches, and I see:
>>
>> $ git push
>> Counting objects: 172, done.
>> Compressing objects: 100% (89/89), done.
>> Writing objects: 100% (89/89), 17.07 KiB, done.
>> Total 89 (delta 80), reused 0 (delta 0)
>> To ssh://git(at)gitmaster(dot)postgresql(dot)org/postgresql.git
>> 35a3def..8a6eb2e REL8_1_STABLE -> REL8_1_STABLE
>> cfb6ac6..b0e2092 REL8_2_STABLE -> REL8_2_STABLE
>> 301a822..0d45e8c REL8_3_STABLE -> REL8_3_STABLE
>> 61f8618..6bd3753 REL8_4_STABLE -> REL8_4_STABLE
>> 09425f8..0a85bb2 REL9_0_STABLE -> REL9_0_STABLE
>> c0b5fac..225f0aa master -> master
>>
>> Now I realize that in addition to the four files there's a "tree" object
>> and a "commit" object, but that still only adds up to 36 objects that
>> should be created in this transaction. How does it get to 172? And
>> then where do the 89 and 80 numbers come from?
>
> IIRC, each directory also counts as an object. So if you change a file
> in a/b/c/d you get 5 commit objects, one for the file and four for the
> directories.
No, not 5 commit objects - 5 trees (for the directories, including the
root directory), 1 blob (for the file), and 1 commit. From gIt(1):
The object database contains objects of three main types: blobs, which
hold file data; trees, which point to blobs and other trees to build up
directory hierarchies; and commits, which each reference a single tree
and some number of parent commits.
So in Tom's case I think we can account for the root directory, src,
src/backend, src/backend/executor, src/backend/optimizer,
src/backend/optimizer/util, src/test, src/test/regress,
src/test/regress/expected, src/test/regress/sql, the 4 files actually
updated, and the commit - 15 objects per branch * 6 branches = 90
objects. I'm not sure why the actual number is 89, unless perhaps two
of the post-commit regression test files were byte-for-byte identical
and got collapsed into a single object. I believe that "delta" refers
to the number of those objects that are stored as deltas against an
existing object (in essence, diffs) rather than as completely new
copies.
I have no idea where the 172 number comes from.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
* Tom Lane: > $ git push > Counting objects: 172, done. > Compressing objects: 100% (89/89), done. > Writing objects: 100% (89/89), 17.07 KiB, done. > Total 89 (delta 80), reused 0 (delta 0) > To ssh://git(at)gitmaster(dot)postgresql(dot)org/postgresql.git > 35a3def..8a6eb2e REL8_1_STABLE -> REL8_1_STABLE > cfb6ac6..b0e2092 REL8_2_STABLE -> REL8_2_STABLE > 301a822..0d45e8c REL8_3_STABLE -> REL8_3_STABLE > 61f8618..6bd3753 REL8_4_STABLE -> REL8_4_STABLE > 09425f8..0a85bb2 REL9_0_STABLE -> REL9_0_STABLE > c0b5fac..225f0aa master -> master > How does it get to 172? These are the number of objects "git push" (actually, git-send-pack, I think) needs to look at more closely, AFAIUI. It's a pretty arbitrary number. You see it sometimes during pull, too. > And then where do the 89 and 80 numbers come from? 89 is the number of objects which need to be transmitted. Of those, 80 were compressed by diffing them to some other object (which might, in turn, be a diff). -- Florian Weimer <fweimer(at)bfk(dot)de> BFK edv-consulting GmbH http://www.bfk.de/ Kriegsstraße 100 tel: +49-721-96201-1 D-76133 Karlsruhe fax: +49-721-96201-99