From: Tomi Ollila <tomi.ollila@iki.fi>
To: Jani Nikula <jani@nikula.org>, notmuch@notmuchmail.org
Subject: Re: [PATCH] emacs: call "notmuch tag" only once when archiving a
	thread
In-Reply-To: <1325615346-8302-1-git-send-email-jani@nikula.org>
References: <1325615346-8302-1-git-send-email-jani@nikula.org>
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	(i686-pc-linux-gnu)
Date: Wed, 04 Jan 2012 16:35:29 +0200
Message-ID: <yf6wr97y1qm.fsf@taco2.nixu.fi>
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On Tue,  3 Jan 2012 20:29:06 +0200, Jani Nikula <jani@nikula.org> wrote:
> Optimize thread archiving by combining all the -inbox tagging operations to
> a single "notmuch tag" call. Also skip redisplay of tag changes in current
> buffer, as it is immediately killed by the archiving functions.
> 
> For threads in the order of tens or a hundred inbox tagged messages, this
> gives a noticeable speedup.
> 
> On the downside, IIRC Xapian does not perform very well if the query (in
> this case a lot of message-ids OR'd together) is very big. It is unknown to
> me at which point this approach would become slower than the original one
> by one tagging approach, if ever.
> 
> Also, this introduces a limitation to the number of messages that can be
> archived at the same time (through ARG_MAX limiting the command line). At
> least on Linux this seems more like a theoretical limitation than a real
> one.

IIRC some systems have like 32768 byte command line limit.
If the change did tagging in like 100-message batches then this limit is
hardly exceeded (if message-id's max 80 characters then command line is
8000+ bytes)...
Hmm -- is there a length limit for message-id. If not maybe when appending 
message id's keep counting length and tag in batches based on that lenght
value.

Hundreds of messages per tagging operation instead of one is good
improvements.

> Signed-off-by: Jani Nikula <jani@nikula.org>

Tomi