PostgreSQL adapter: quote_string is not thread safe

>> puts $$
94100
>> PGconn.escape('test')
=> "test"
>> PGconn.new({}).escape('test')
=> "test"

 sudo dtrace -n 'pid94100::PQescapeString:entry { printf("it called me\n") } pid94100::PQescapeStringConn:entry { printf("it called me\n") }'
dtrace: description 'pid94100::PQescapeString:entry ' matched 2 probes
CPU     ID                    FUNCTION:NAME
  1  22323             PQescapeString:entry it called me

  0  22324         PQescapeStringConn:entry it called me

http://www.postgresql.org/docs/8...

PQescapeString can be used safely in single-threaded client programs that work with only one PostgreSQL connection at a time (in this case it can find out what it needs to know "behind the scenes"). In other contexts it is a security hazard and should be avoided in favor of PQescapeStringConn.