log slow queries and hints

Hello. I'm new with postgresql, some times ago i'm turn on log slow
queries, but log file contains not only queries , nor
Oct 28 13:03:44 selfip postgres[18072]: [5-1]
user=dbu_vase_1,db=db_vase_1 WARNING:  nonstandard use of \\ in a string
literal at character 90
Oct 28 13:03:44 selfip postgres[18072]: [5-2]
user=dbu_vase_1,db=db_vase_1 HINT:  Use the escape string syntax for
backslashes, e.g., E'\\'.


How can i disable this hints, or (i'm use drupal for this database) fix
queries?

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Vasiliy G Tolstov <v.tolstov@selfip.ru>
Selfip.Ru