Re: [RFC] Faster git grep.

> Ondřej Bílka <neleai@seznam.cz> writes:
> 
> > One solution would be to use same trick as was done in google code. 
> > Build and keep database of trigraphs and which files contain how many of
> > them. When querry is made then check
> > only these files that have appropriate combination of trigraphs.
> 
> This depends on how you go about trying to reducing the database
> overhead, I think.  For example, a very naive approach would be to
> create such trigraph hit index for each and every commit for all
> paths.  When "git grep $commit $pattern" is run, you would consult
> such table with $commit and potential trigraphs derived from the
> $pattern to grab the potential paths your hits _might_ be in.
>

> But the contents of a path usually do not change in each and every
> commit.  So you may want to instead index with the blob object names
> (i.e. which trigraphs appear in what blobs).  But once you go that
> route, your "git grep $commit $pattern" needs to read and enumerate
> all the blobs that appear in $commit's tree, and see which blobs may
> potentially have hits.  Then you would need to build an index every
> time you make a new commit for blobs whose trigraphs have not been
> counted.
> 
> Nice thing is that once a blob (or a commit for that matter) is
> created and its object name is known, its contents will not change,
> so you can index once and reuse it many times.  But I am not yet
> convinced if pre-indexing is an overall win, compared to the cost of
> maintaining such a database.