Merging Related Information from 2 Tables

Martin McCormick martin at
Thu Oct 29 15:39:15 UTC 2009

This is probably going to be a hashing exercise but I am
checking to see if any of the building blocks needed are already
out there.

	The problem is simple to describe in that there are 2
tables. One is a DNS zone transfer table of all the A or Address
records in a given zone or from several zones for that matter.
the other table is from the same zones and consists of text or
TXT records. The only thing the 2 tables have in common is that
some of the TXT records share the exact same name field as the A
records so we should be able to display the important contents
of the A and TXT records on the same line if their names match.
The challenge is to do this quickly so some sort of hash
function is needed to locate A and TXT records having
the same name.

Grep does this beautifully for single entries across multiple
files, but I need to merge the text part of the TXT record with
the IP address and host name from the A record with the same
name. The only hard part is finding the quickest way to match
the roughly 25,000 host names in the A records with around half
as many TXT records. This is basically a bucket list problem in
which we can either have an A record name in a bucket by itself
or an A record in a given bucket and a TXT record in another
bucket with the same name as the A record.

	In the interest of standing on the shoulders of giants,
I am checking to see how much tried and tested tools already
exist and how much needs to be home-grown.

	It is also possible to use egrep to search for A and TXT
records in 1 pass through a file in which case one would search
from the same file for both record types but the problem is the
same. In case anybody wonders:

egrep '([[:space:]]IN([[:space:]]TXT[[:space:]]|[[:space:]]A[[:space:]]))' >ATXT.txt

The line break here is for Email consideration. The above
command should all be on one line.

	Thanks for any suggestions.

Martin McCormick WB5AGZ  Stillwater, OK 
Systems Engineer
OSU Information Technology Department Telecommunications Services Group

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