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From: Jeff King <>
To: "Ævar Arnfjörð Bjarmason" <>
Cc: Martin Langhoff <>,
	Git Mailing List <>,
	Taylor Blau <>
Subject: Re: git log exclude pathspec from file - supported? plans?
Date: Thu, 1 Jul 2021 17:43:23 -0400	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, Jul 01, 2021 at 05:27:05PM -0400, Jeff King wrote:

> > One of the PCREv2 experiments I had very early WIP work towards was to
> > create a search index for commit messages, contents etc. and stick it in
> > something similar to the --changed-paths part of the commit-graph.
> Yeah, to some degree --change-paths may mitigate this, since for a
> series of simple pathspecs we'd generate the bloom filter once and then
> get O(1) matching per commit.

The timings for "git rev-list" I shared earlier were with commit-graphs,
but not with changed-path filters. They don't seem to help much, though.

I suspect the reason is that they can never give a definite answer. They
can only say "probably, yes, this commit is worth looking at". And then
we have to do the same slow, linear pathspec match on that commit. And
if your pathspec contains virtually every path in the first place, then
the answer from the bloom filters will always be "probably, yes".

So I guess they are not really a silver bullet here.


      parent reply	other threads:[~2021-07-01 21:43 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2021-06-30 16:59 ` git log exclude pathspec from file - supported? plans? Martin Langhoff
2021-06-30 17:58   ` Jeff King
2021-06-30 18:22     ` Ævar Arnfjörð Bjarmason
2021-07-01 21:27       ` Jeff King
2021-07-01 21:30         ` [PATCH 1/3] pathspec: add optional trie index Jeff King
2021-07-01 21:30         ` [PATCH 2/3] pathspec: turn on tries when appropriate Jeff King
2021-07-01 21:36         ` [PATCH 3/3] tree-diff: use pathspec tries Jeff King
2021-07-01 21:43         ` Jeff King [this message]

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