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From: Elijah Newren <newren@gmail.com>
To: Phil Hord <phil.hord@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>
Subject: Re: [PATCH 1/1] delete multiple tags in a single transaction
Date: Thu, 8 Aug 2019 11:15:24 -0700
Message-ID: <CABPp-BFH++aJinkzg+qsZDRN6R5-E8LPCG_u+udZLW6o0MGBug@mail.gmail.com> (raw)
In-Reply-To: <20190808035935.30023-1-phil.hord@gmail.com>

On Wed, Aug 7, 2019 at 9:11 PM Phil Hord <phil.hord@gmail.com> wrote:
>
> From: Phil Hord <phil.hord@gmail.com>
>
> 'git tag -d' accepts one or more tag refs to delete, but each deletion
> is done by calling `delete_ref` on each argv. This is painfully slow
> when removing from packed refs. Use delete_refs instead so all the
> removals can be done inside a single transaction with a single write.

Nice, thanks for working on this.

> I have a repo with 24,000 tags, most of which are not useful to any
> developers. Having this many refs slows down many operations that
> would otherwise be very fast. Removing these tags when they've been
> accidentally fetched again takes about 30 minutes using delete_ref.

I also get really slow times on a repo with ~20,000 tags (though order
~3 minutes rather than ~30, probably due to having an SSD on this
machine) -- but ONLY IF the refs are packed first (git pack-refs
--all).  If the refs are loose, it's relatively quick to delete a
dozen thousand or so tags (order of a few seconds).  It might be worth
mentioning in the commit message that this only makes a significant
difference in the case where the refs are packed.

>     git tag -l feature/* | xargs git tag -d
>
> Removing the same tags using delete_refs takes less than 5 seconds.

It appears this same bug also affects `git branch -d` when deleting
lots of branches (or remote tracking branches) and they are all
packed; could you apply the same fix there?

In constrast, it appears that `git update-ref --stdin` is fast
regardless of whether the refs are packed, e.g.
   git tag -l feature/* | sed -e 's%^%delete refs/tags/%' | git
update-ref --stdin
finishes quickly (order of a few seconds).

  parent reply	other threads:[~2019-08-08 18:15 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-08  3:59 Phil Hord
2019-08-08 12:47 ` Martin Ågren
2019-08-08 12:53   ` [PATCH] t7004: check existence of correct tag Martin Ågren
2019-08-08 18:15 ` Elijah Newren [this message]
2019-08-08 23:43   ` [PATCH 1/1] delete multiple tags in a single transaction Phil Hord
2019-08-09  3:05     ` Jeff King
2019-08-08 19:39 ` Junio C Hamano
2019-08-08 23:58   ` Phil Hord

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