From: Junio C Hamano <gitster@pobox.com>
To: Christian Couder <christian.couder@gmail.com>
Cc: git@vger.kernel.org, "Nguyen Thai Ngoc Duy" <pclouds@gmail.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Christian Couder" <chriscool@tuxfamily.org>
Subject: Re: [PATCH v1 00/19] Add configuration options for split-index
Date: Mon, 24 Oct 2016 11:07:59 -0700 [thread overview]
Message-ID: <xmqq8ttd7h8g.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <20161023092648.12086-1-chriscool@tuxfamily.org> (Christian Couder's message of "Sun, 23 Oct 2016 11:26:29 +0200")
Christian Couder <christian.couder@gmail.com> writes:
> The design is similar as the previous work that introduced
> "core.untrackedCache".
>
> The new "core.splitIndex" configuration option can be either true,
> false or undefined which is the default.
>
> When it is true, the split index is created, if it does not already
> exists, when the index is read. When it is false, the split index is
> removed if it exists, when the index is read. Otherwise it is left as
> is.
I admit I haven't thought it through, but this sounds OK.
> Along with this new configuration variable, the two following options
> are also introduced:
>
> - splitIndex.maxPercentChange
>
> This is to avoid having too many changes accumulating in the split
> index while in split index mode. The git-update-index
> documentation says:
>
> If split-index mode is already enabled and `--split-index` is
> given again, all changes in $GIT_DIR/index are pushed back to
> the shared index file.
>
> but it is probably better to not expect the user to think about it
> and to have a mechanism that pushes back all changes to the shared
> index file automatically when some threshold is reached.
>
> The default threshold is when the number of entries in the split
> index file reaches 20% (by default) of the number of entries in
> the shared index file. The new "splitIndex.maxPercentChange"
> config option lets people tweak this value.
OK.
> - splitIndex.sharedIndexExpire
>
> To make sure that old sharedindex files are eventually removed
> when a new one has been created, we "touch" the shared index file
> every time it is used by a new split index file. Then we can
> delete shared indexes with an mtime older than one week (by
> default), when we create a new shared index file. The new
> "splitIndex.sharedIndexExpire" config option lets people tweak
> this grace period.
I do not quite understand this justification. Doesn't each of the
"this hold only changes since the base index file" files have a
backpointer that names the base index file it is a delta against?
Is it safe to remove a base index file when there is still a split
index file that points at it?
IOW, I do not see why it can be safe for the expiration decision to
be based on timestamp (I would understand it if it were based on a
refcnt, though).
next prev parent reply other threads:[~2016-10-24 18:08 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-23 9:26 [PATCH v1 00/19] Add configuration options for split-index Christian Couder
2016-10-23 9:26 ` [PATCH v1 01/19] split-index: s/eith/with/ typo fix Christian Couder
2016-10-23 9:26 ` [PATCH v1 02/19] config: add git_config_get_split_index() Christian Couder
2016-10-23 9:26 ` [PATCH v1 03/19] split-index: add {add,remove}_split_index() functions Christian Couder
2016-10-25 9:58 ` Duy Nguyen
2016-10-29 22:06 ` Christian Couder
2016-11-07 10:08 ` Duy Nguyen
2016-11-09 9:24 ` Duy Nguyen
2016-11-09 14:47 ` Christian Couder
2016-10-23 9:26 ` [PATCH v1 04/19] read-cache: add and then use tweak_split_index() Christian Couder
2016-10-23 9:26 ` [PATCH v1 05/19] update-index: warn in case of split-index incoherency Christian Couder
2016-10-25 10:00 ` Duy Nguyen
2016-10-29 22:19 ` Christian Couder
2016-11-01 19:05 ` Junio C Hamano
2016-11-01 23:00 ` Christian Couder
2016-11-02 1:37 ` Junio C Hamano
2016-10-23 9:26 ` [PATCH v1 06/19] t1700: add tests for core.splitIndex Christian Couder
2016-10-23 9:26 ` [PATCH v1 07/19] Documentation/config: add information " Christian Couder
2016-10-23 9:26 ` [PATCH v1 08/19] Documentation/git-update-index: talk about core.splitIndex config var Christian Couder
2016-10-23 9:26 ` [PATCH v1 09/19] config: add git_config_get_max_percent_split_change() Christian Couder
2016-10-25 10:06 ` Duy Nguyen
2016-10-29 22:24 ` Christian Couder
2016-11-01 19:13 ` Junio C Hamano
2016-11-05 0:27 ` Christian Couder
2016-10-23 9:26 ` [PATCH v1 10/19] read-cache: regenerate shared index if necessary Christian Couder
2016-10-23 16:07 ` Ramsay Jones
2016-10-29 22:40 ` Christian Couder
2016-10-25 10:16 ` Duy Nguyen
2016-10-29 22:58 ` Christian Couder
2016-10-23 9:26 ` [PATCH v1 11/19] t1700: add tests for splitIndex.maxPercentChange Christian Couder
2016-11-01 19:15 ` Junio C Hamano
2016-10-23 9:26 ` [PATCH v1 12/19] Documentation/config: add splitIndex.maxPercentChange Christian Couder
2016-11-01 19:19 ` Junio C Hamano
2016-11-05 0:45 ` Christian Couder
2016-11-06 17:16 ` Junio C Hamano
[not found] ` <CAP8UFD1YL+RgdqbV0V1OnC=sJHJFc_an02Q9JeDNapW+u1CZcA@mail.gmail.com>
2016-11-07 9:38 ` Duy Nguyen
2016-11-18 14:34 ` Christian Couder
2016-11-22 10:35 ` Duy Nguyen
2016-11-22 13:13 ` Christian Couder
2016-11-22 13:20 ` Duy Nguyen
2016-10-23 9:26 ` [PATCH v1 13/19] sha1_file: make check_and_freshen_file() non static Christian Couder
2016-10-23 9:26 ` [PATCH v1 14/19] read-cache: touch shared index files when used Christian Couder
2016-10-25 10:26 ` Duy Nguyen
2016-11-01 19:23 ` Junio C Hamano
2016-10-23 9:26 ` [PATCH v1 15/19] config: add git_config_get_date_string() from gc.c Christian Couder
2016-11-01 19:28 ` Junio C Hamano
2016-11-23 15:04 ` Christian Couder
2016-11-23 17:34 ` Junio C Hamano
2016-11-28 16:19 ` Christian Couder
2016-11-28 16:56 ` Junio C Hamano
2016-10-23 9:26 ` [PATCH v1 16/19] read-cache: unlink old sharedindex files Christian Couder
2016-10-25 10:43 ` Duy Nguyen
2016-10-27 10:25 ` Duy Nguyen
2016-10-27 12:14 ` Christian Couder
2016-10-27 16:13 ` Junio C Hamano
2016-10-29 3:30 ` Duy Nguyen
2016-10-23 9:26 ` [PATCH v1 17/19] t1700: test shared index file expiration Christian Couder
2016-10-23 9:26 ` [PATCH v1 18/19] Documentation/config: add splitIndex.sharedIndexExpire Christian Couder
2016-10-23 9:26 ` [PATCH v1 19/19] Documentation/git-update-index: explain splitIndex.* Christian Couder
2016-10-24 18:07 ` Junio C Hamano [this message]
2016-10-25 9:30 ` [PATCH v1 00/19] Add configuration options for split-index Duy Nguyen
2016-10-25 17:21 ` Junio C Hamano
2016-10-26 9:25 ` Duy Nguyen
2016-10-26 16:14 ` Junio C Hamano
2016-10-25 10:52 ` Duy Nguyen
2016-11-03 14:34 ` Christian Couder
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