[Pgpool-general] Problem with DBI and Load Balancing

[Julian Scarfe]

I've been trying out master-slave and load-balancing mode with DBI, the Perl 
database interface (and DBD::Pg).  All queries seem to go to the master.

The problem seems to be that DBI (or DBD::Pg, I don't know which), inserts 
whitespace before the query:

Dec 18 12:14:56 kutta postgres[29981]: [4-1] LOG:  statement: SELECT 
version()
Dec 18 12:14:56 kutta postgres[29981]: [5-1] LOG:  statement: 
SELECT host from host
Dec 18 12:14:56 kutta postgres[29981]: [6-1] LOG:  statement:  RESET ALL
Dec 18 12:14:56 kutta postgres[29981]: [7-1] LOG:  statement:  SET SESSION 
AUTHORIZATION DEFAULT

Note the spaces before my statement, "SELECT host from host", which I didn't 
introduce.  I imagine that's what's causing pgpool to send the query only to 
the master.  The significance of leading whitespace is clearly documented on 
the pgpool page and is obvious from the code.

/*
 * return non 0 if load balance is possible
 */
static int load_balance_enabled(POOL_CONNECTION_POOL *backend, char *sql)
{
 if (pool_config.load_balance_mode &&
  DUAL_MODE &&
  MAJOR(backend) == PROTO_MAJOR_V3 &&
  TSTATE(backend) == 'I' &&
  !strncasecmp(sql, "SELECT", 6))
  return 1;
 return 0;
}

Would it be possible to have an ignore_leading_whitespace option (or even 
default to ignoring leading whitespace) for compatibility please?

Julian Scarfe