$sth_mlg_addr_duplicate_check->execute($fields[17],$fields[18],$fields
+[19],$fields[20],$fields[21],$fields[22],$fields[23])
      or warn "While checking for duplicate mailing address $fields[17
+]; $fields[19] $fields[20]: " . $dbh->errstr;
    ($mlg_addr_id) = $sth_mlg_addr_duplicate_check->fetchrow_array();

    my $mlg_id;
    if(!defined($mlg_addr_id) && length($fields[20]) == 2){
      $sth_insert_mlg_addr->execute($fields[17],$fields[18],$fields[19
+],$fields[20],$fields[21],$fields[22],$fields[23])
        or warn "While inserting new mailing address |$fields[17]|; |$
+fields[19]| |$fields[20]|, with id |$mlg_addr_id|: " . $dbh->errstr;
      $sth_mlg_addr_duplicate_check->execute($fields[17],$fields[18],$
+fields[19],$fields[20],$fields[21],$fields[22],$fields[23])
        or warn "While checking for duplicate mailing address |$fields
+[17]|; |$fields[19]| |$fields[20]|: " . $dbh->errstr;
      ($mlg_addr_id) = $sth_mlg_addr_duplicate_check->fetchrow_array()
+;
      $mlg_id = $mlg_addr_id;
    } else {
      $mlg_id = $mlg_addr_id;
      # print STDERR "\$mlg_addr_id is already defined as $mlg_addr_id
+.\n";
    }
[download]

Use of uninitialized value in concatenation (.) or string at parse_vot
+er_list.pl line 251, <$fh> line 3483.
While inserting new mailing address |xxxx RUE LOUIS PHILLIPPE|; |MARRE
+RO| |LA|, with id ||: ERROR:  duplicate key violates unique constrain
+t "mlg_addr_uniq_key"
While checking for duplicate mailing address |xxxx RUE LOUIS PHILLIPPE
+|; |MARRERO| |LA|: ERROR:  current transaction is aborted, commands i
+gnored until end of transaction block
While checking for duplicate residential address: ERROR:  current tran
+saction is aborted, commands ignored until end of transaction block
Issuing rollback() for database handle being DESTROY'd without explici
+t disconnect().
[download]

=# SELECT * FROM mlg_addr WHERE address1 LIKE '%RUE LOUIS PHILLIPPE' A
+ND city = 'MARRERO' AND state = 'LA';
 mlg_addr_id | address1 | address2 | city | state | zipcode5 | zipcode
+4 | country
-------------+----------+----------+------+-------+----------+--------
+--+---------
(0 rows)
[download]

my $mlg_addr_duplicate_check =<<EOQ;
SELECT mlg_addr_id FROM mlg_addr WHERE
address1 = ? AND address2 = ? AND city = ? AND state = ?
AND zipcode5 = ? AND  zipcode4 = ? AND country = ?
EOQ

my $sth_mlg_addr_duplicate_check = $dbh->prepare($mlg_addr_duplicate_c
+heck) or die $dbh->errstr;

my $insert_mlg_addr =<<EOQ;
INSERT INTO mlg_addr
(address1,address2,city,state,zipcode5,zipcode4,country)
VALUES(?,?,?,?,?,?,?);
EOQ

my $sth_insert_mlg_addr = $dbh->prepare($insert_mlg_addr) or die $dbh-
+>errstr;
[download]

=# \d mlg_addr
                                     Table "public.mlg_addr"
   Column    |         Type          |                         Modifie
+rs
-------------+-----------------------+--------------------------------
+---------------------------
 mlg_addr_id | integer               | not null default nextval(('mlg_
+addr_id'::text)::regclass)
 address1    | character varying(65) |
 address2    | character varying(65) |
 city        | character varying(40) |
 state       | character varying(2)  |
 zipcode5    | character varying(5)  |
 zipcode4    | character varying(4)  |
 country     | character varying(45) |
Indexes:
    "mlg_addr_id_key" UNIQUE, btree (mlg_addr_id)
    "mlg_addr_uniq_key" UNIQUE, btree (country, zipcode5, zipcode4, ad
+dress1, address2)
[download]

address1 = $fields[17]
address2 = $fields[18]
city = $fields[19]
state = $fields[20]
zipcode5 = $fields[21]
zipcode4 = $fields[22]
country = $fields[13]
[download]

Why would this query fail when there obviously is no duplicate in that table?

-- Hugh

UPDATE:

In response to moritz's questions about the details on the schema and the queries and variables, I've added some of the gruesome details behind the readmore tags.