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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Derrick Stolee <stolee@gmail.com>
Cc: "Jeff King" <peff@peff.net>,
	"SZEDER Gábor" <szeder.dev@gmail.com>,
	"Stefan Beller" <sbeller@google.com>, git <git@vger.kernel.org>,
	"Duy Nguyen" <pclouds@gmail.com>
Subject: Re: Bloom Filters (was Re: We should add a "git gc --auto" after "git clone" due to commit graph)
Date: Tue, 09 Oct 2018 20:45:11 +0200
Message-ID: <87ftxfez7s.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <f877020c-3098-e4c4-ad64-cca57f764b91@gmail.com>


On Tue, Oct 09 2018, Derrick Stolee wrote:

> The filter needs to store every path that would be considered "not
> TREESAME". It can't store wildcards, so you would need to evaluate the
> wildcard and test all of those paths individually (not a good idea).

If full paths are stored, yes, But have you considered instead of
storing paths, storing all trigrams that can be extracted from changed
paths at that commit?

I.e. instead of a change to "t/t0000-basic.sh" storing
"t/t0000-basic.sh" we'd store ["t/t", "/t0", "t00", "000", "00-" ...]
etc.

That sort of approach would mean that e.g. "t*000*", "*asi*.sh"
etc. could all be indexed, and as long as we could find three
consecutive bytes of fixed string we'd have a chance to short-circuit,
but would need to degrade to a full tree unpack for e.g. "t*". We could
also special-case certain sub-three-char indexes, or to
"bi-grams". E.g. to be able to index '*.c' or 't*' (first char at the
beginning of a string only).

It would mean having to check more things in the bloom filter for each
commit, but that's going to be hot in cache at that point so it'll
probably beat unpacking trees by far, and we could short-circuit exit at
the first one that returned false.

  reply index

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-03 13:23 We should add a "git gc --auto" after "git clone" due to commit graph Ævar Arnfjörð Bjarmason
2018-10-03 13:36 ` SZEDER Gábor
2018-10-03 13:42   ` Derrick Stolee
2018-10-03 14:18     ` Ævar Arnfjörð Bjarmason
2018-10-03 14:01   ` Ævar Arnfjörð Bjarmason
2018-10-03 14:17     ` SZEDER Gábor
2018-10-03 14:22       ` Ævar Arnfjörð Bjarmason
2018-10-03 14:53         ` SZEDER Gábor
2018-10-03 15:19           ` Ævar Arnfjörð Bjarmason
2018-10-03 16:59             ` SZEDER Gábor
2018-10-05  6:09               ` Junio C Hamano
2018-10-10 22:07                 ` SZEDER Gábor
2018-10-10 23:01                   ` Ævar Arnfjörð Bjarmason
2018-10-03 19:08           ` Stefan Beller
2018-10-03 19:21             ` Jeff King
2018-10-03 20:35               ` Ævar Arnfjörð Bjarmason
2018-10-03 17:47         ` Stefan Beller
2018-10-03 18:47           ` Ævar Arnfjörð Bjarmason
2018-10-03 18:51             ` Jeff King
2018-10-03 18:59               ` Derrick Stolee
2018-10-03 19:18                 ` Jeff King
2018-10-08 16:41                   ` SZEDER Gábor
2018-10-08 16:57                     ` Derrick Stolee
2018-10-08 18:10                       ` SZEDER Gábor
2018-10-08 18:29                         ` Derrick Stolee
2018-10-09  3:08                           ` Jeff King
2018-10-09 13:48                             ` Bloom Filters (was Re: We should add a "git gc --auto" after "git clone" due to commit graph) Derrick Stolee
2018-10-09 18:45                               ` Ævar Arnfjörð Bjarmason [this message]
2018-10-09 18:46                               ` Jeff King
2018-10-09 19:03                                 ` Derrick Stolee
2018-10-09 21:14                                   ` Jeff King
2018-10-09 23:12                                     ` Bloom Filters Jeff King
2018-10-09 23:13                                       ` [PoC -- do not apply 1/3] initial tree-bitmap proof of concept Jeff King
2018-10-09 23:14                                       ` [PoC -- do not apply 2/3] test-tree-bitmap: add "dump" mode Jeff King
2018-10-10  0:48                                         ` Junio C Hamano
2018-10-11  3:13                                           ` Jeff King
2018-10-09 23:14                                       ` [PoC -- do not apply 3/3] test-tree-bitmap: replace ewah with custom rle encoding Jeff King
2018-10-10  0:58                                         ` Junio C Hamano
2018-10-11  3:20                                           ` Jeff King
2018-10-11 12:33                                       ` Bloom Filters Derrick Stolee
2018-10-11 13:43                                         ` Jeff King
2018-10-09 21:30                             ` We should add a "git gc --auto" after "git clone" due to commit graph SZEDER Gábor
2018-10-09 19:34                       ` [PATCH 0/4] Bloom filter experiment SZEDER Gábor
2018-10-09 19:34                         ` [PATCH 1/4] Add a (very) barebones Bloom filter implementation SZEDER Gábor
2018-10-09 19:34                         ` [PATCH 2/4] commit-graph: write a Bloom filter containing changed paths for each commit SZEDER Gábor
2018-10-09 21:06                           ` Jeff King
2018-10-09 21:37                             ` SZEDER Gábor
2018-10-09 19:34                         ` [PATCH 3/4] revision.c: use the Bloom filter to speed up path-limited revision walks SZEDER Gábor
2018-10-09 19:34                         ` [PATCH 4/4] revision.c: add GIT_TRACE_BLOOM_FILTER for a bit of statistics SZEDER Gábor
2018-10-09 19:47                         ` [PATCH 0/4] Bloom filter experiment Derrick Stolee
2018-10-11  1:21                         ` [PATCH 0/2] Per-commit filter proof of concept Jonathan Tan
2018-10-11  1:21                           ` [PATCH 1/2] One filter per commit Jonathan Tan
2018-10-11  1:21                           ` [PATCH 2/2] Only make bloom filter for first parent Jonathan Tan
2018-10-11  7:37                           ` [PATCH 0/2] Per-commit filter proof of concept Ævar Arnfjörð Bjarmason
2018-10-15 14:39                         ` [PATCH 0/4] Bloom filter experiment Derrick Stolee
2018-10-16  4:45                           ` Junio C Hamano
2018-10-16 11:13                             ` Derrick Stolee
2018-10-16 12:57                               ` Ævar Arnfjörð Bjarmason
2018-10-16 13:03                                 ` Derrick Stolee
2018-10-18  2:00                                 ` Junio C Hamano
2018-10-16 23:41                           ` Jonathan Tan
2018-10-08 23:02                     ` We should add a "git gc --auto" after "git clone" due to commit graph Junio C Hamano
2018-10-03 14:32     ` Duy Nguyen
2018-10-03 16:45 ` Duy Nguyen
2018-10-04 21:42 ` [RFC PATCH] " Ævar Arnfjörð Bjarmason
2018-10-05 12:05   ` Derrick Stolee
2018-10-05 13:05     ` Ævar Arnfjörð Bjarmason
2018-10-05 13:45       ` Derrick Stolee
2018-10-05 14:04         ` Ævar Arnfjörð Bjarmason
2018-10-05 19:21         ` Jeff King
2018-10-05 19:41           ` Derrick Stolee
2018-10-05 19:47             ` Jeff King
2018-10-05 20:00               ` Derrick Stolee
2018-10-05 20:02                 ` Jeff King
2018-10-05 20:01               ` Ævar Arnfjörð Bjarmason
2018-10-05 20:09                 ` Jeff King
2018-10-11 12:49 [PATCH 1/2] One filter per commit Derrick Stolee
2018-10-11 19:11 ` [PATCH] Per-commit and per-parent filters for 2 parents Jonathan Tan

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