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https://issues.apache.org/jira/browse/COUCHDB-1130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13021835#comment-13021835
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Paul Joseph Davis commented on COUCHDB-1130:
--------------------------------------------
The first thing I noticed is that v3 while faster has a much broader range than
v2. I played around with the first function a bit to see if I could improve it
a bit. I think I did, but I also notice that reordering the functions appears
to impact the ranges reported as well. I think to get anything meaningful we'd
need to run many more iterations and get a better statistical understanding of
it.
I'm +1 on switching to either v2 or v3.
Good work Randall.
> binary optimization in couch_file
> ---------------------------------
>
> Key: COUCHDB-1130
> URL: https://issues.apache.org/jira/browse/COUCHDB-1130
> Project: CouchDB
> Issue Type: Improvement
> Components: Database Core
> Affects Versions: 1.0.2
> Reporter: Randall Leeds
> Priority: Minor
> Attachments:
> 0001-refactor-remove_block_prefixes-2-for-optimization.patch,
> davisp_prof_bin_opt, prof_bin_opt
>
>
> I've had this patch sitting around since January and kept forgetting to file
> the ticket. Hurray spring cleaning.
> Just for fun I ran erlc with +bin_opt_info, which gives information about how
> the Erlang VM can optimize creating binary objects.
> What follows is the commit message from my patch.
> Even if I'm wrong about the last point, it can't hurt.
> What think you all?
> -------------------
> Running erlc with +bin_opt_info gives an INFO message stating that "matching
> anything else but a plain variable to the left of a binary pattern will
> prevent
> delayed sub binary optimization; SUGGEST changing argument order"
> I guess matching 0 is triggering this. If I understand correctly, this change
> will allow the compiler to skip creating a sub-binary that starts at the block
> boundary in the third clause and delay creation until we strip the leading
> byte
> in the 0 clause. This means one less 1-byte binary every time we read across a
> block boundary.
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