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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: bitmap slices
Date Mon, 01 Feb 2010 15:42:16 GMT
how would this be different then the byte[] column name you can
already match on?

2010/2/1 Ted Zlatanov <tzz@lifelogs.com>:
> On Fri, 29 Jan 2010 15:07:01 -0600 Ted Zlatanov <tzz@lifelogs.com> wrote:
>
> TZ> On Fri, 29 Jan 2010 12:06:28 -0600 Jonathan Ellis <jbellis@gmail.com> wrote:
> JE> On Fri, Jan 29, 2010 at 9:09 AM, Mehar Chaitanya
> JE> <meharchaitanya@gmail.com> wrote:
>>>>   1. This would lead to enourmous amount of duplication of data, in short
>>>>   if I now want to view the data from IS_PUBLISHED dimenstion then my database
>>>>   size would scale up tremendously.
>
> JE> Yes.  But disk space is so cheap it's worth using a lot of it to make
> JE> other things fast.
>
> TZ> IIUC, Mehar would be duplicating the article data for every article tag.
>
> TZ> I searched the bug tracker and wiki and didn't find anything on the
> TZ> topic of tag storage and search, so I don't think Cassandra supports
> TZ> tags without data duplication.
>
> TZ> Would it be possible to implement an optional byte[] bitmap field in
> TZ> SliceRange?  If you can specify the bitmap as an optional field it would
> TZ> not break current clients.  Then the search can return only the subset
> TZ> of the range that matches the bitmap.  This would make sense for
> TZ> BytesType and LongType, at least.
>
> I looked at the source code and it seems that
> StorageProxy::getSliceRange() is the focal point for reads and bitmap
> matching should be implemented there.  The bitmap could be applied as a
> filter before the other SliceRange parameters, especially the max number
> of return results.  It may be worth the effort to send the bitmap down
> to the ReadCommand/ColumnFamily level to reduce the number of potential
> matches.
>
> If this is not feasible for technical reasons I'd like to know.
> Otherwise I'll put it on my TODO list and produce a proposal (unless
> someone more knowledgeable is interested, of course).
>
> Ted
>
>

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