Problem with reading data from standby server ?

Hello,

when I read binary replication tutorial 
(http://wiki.postgresql.org/wiki/Binary_Replication_Tutorial) I see on 
Hot Standby: Hot Standby is identical to Warm Standby, except that the 
Standby is available to run read-only queries.
I setup hot standby server described in tutorial and it's working fine, 
no problem with that. I have a problem when I try to start a script that 
should read whole table, error message from php is:

PHP Warning:  pg_query(): Query failed: ERROR:  canceling statement due 
to conflict with recovery
DETAIL:  User query might have needed to see row versions that must be 
removed. in dump.php on line 68
PHP Warning:  pg_fetch_array() expects parameter 1 to be resource, 
boolean given in dump.php on line 69
PHP Warning:  pg_query(): Query failed: ERROR:  canceling statement due 
to conflict with recovery
DETAIL:  User query might have needed to see row versions that must be 
removed. in dump.php on line 235
PHP Warning:  pg_fetch_array() expects parameter 1 to be resource, 
boolean given in dump.php on line 236


Script actually start sql query:

SELECT abs.id, array_accumulate(abs.status) AS status, 
array_accumulate(abs.service) AS service, stb.model FROM statuses abs, 
stb_tbl stb WHERE abs.id = stb.ser
  AND abs.service != 8 AND abs.id LIKE '432%' GROUP BY abs.id, stb.model 
ORDER BY abs.id


array_accumulate aggregate is:


CREATE AGGREGATE array_accumulate (
     sfunc = array_append,
     basetype = anyelement,
     stype = anyarray,
     initcond = '{}'
);


When data is fetched it's saved into a file after some modifications. 
This script is work a 30-40 min until all data is parsed. Well, I think 
problem is started when master server send new wal file to slave, but 
how I can resolve that problem ?



Any solutions or some one to can point me how I can resolve this 
problem ?


Regards,
Condor