On Wed, Jun 18, 2014 at 12:18 PM, Eric Rubin-Smith <eas....@gmail.com> wrote:
> Carlos Ferreira wrote: > > > 1 - There a data type named IPV6 Address. 2 - there is a table where > > this data type must be in. ( can be a set of fields, one blob, one > string > > ...) > > > > You want to: > > > > Given a certain IPV6, find in the database the existent IPV6 record with > > the longest equal prefix to the given IPV6 value. > > Not quite. Perhaps you were confused by my (probably unclear) use of > the word "prefix". > > The data structure contains a set of IPv6 *network prefixes*. A prefix > is the first N bits of an IPv6 address and is denoted as an IP address > with a suffix of (128-N) bits of zeros, along with the length of the > prefix: > > feed:beef::/32 > > (here N==32). > > An IPv6 address is inside this prefix iff its first 32 bits are equal to > feed:beef. The phrase you're looking for here is "CIDR block". The way I'd handle this is something like this: Expand the prefix into the full feed:beef:0000:etc Insert into a table (start binary(16), mask_length int) select top 1 binary,length from table where start <= @input order by binary desc Check if the row is inside the range returned. This will take a single index seek. -- Cory Nelson http://int64.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
