[notmuch] strange behavior of indexing of and searching for strings containing '[]'

[Olly Betts]

On 2010-02-05, Jameson Rollins wrote:
> Hey, folks.  I've been noticing some strange behavior of notmuch search
> results for strings containing '[]'.  Here are some searches for some
> exact strings in messages subjects:

The '[]' is a red herring.  Xapian's TermGenerator and QueryParser classes
treat these two characters pretty much as if they were spaces.

> servo:~ 0$ notmuch search subject:'emacs paned UI'

Note that the '' is quoting for the shell only here.  So Xapian sees:

    subject:emacs paned UI

Assuming you are defaulting to an AND search, that's `emacs in the subject'
AND `paned anywhere in the indexed text' AND `UI anywhere in the indexed text'.

To specify a quoted phrase you want "" anyway (not ''), so the command
matching what I think you intended to search for is:

    notmuch search 'subject:"emacs paned UI"'
 
> servo:~ 0$ notmuch search subject:'[notmuch] emacs paned UI'

    notmuch search 'subject:"[notmuch] emacs paned UI"'

Which should return identical results to:

    notmuch search 'subject:"notmuch emacs paned UI"'

> thread:5f2cb4b108773a39161b33c86e54f7fd  4 mins. ago [1/1] Jameson Rollins;=
>  [notmuch] loss of duplicate messages (inbox)
> servo:~ 0$=20
>
> Not only did it not turn up the message that *does* match that exact
> string in it's subject line, it actually turns up a completely different
> message that doesn't match the search term at all!

It matches the notmuch in the subject, and presumably emacs, paned, and UI
in the body.

> [snip the rest - the same explanations apply]

Cheers,
    Olly