Postgres db-engine ignores schema information in getDropIndexSql() method

[Nicklas Nordborg]

This causes problem when applying the performance fix in 2.4.4 (#796) since Postgres is not able to find the indexes that are going to be dropped. A possible workaround (submitted by Pawel Sztromwasser) is to extend the search path using the following SQL:

ALTER [base_user_name] SET search_path TO 
"$user",public,[base_dynamic_schema_name];

This command executed from psql PostgreSql client adds dynamic schema to the default search_path.

[Nicklas Nordborg]

(In [3906]) Fixes #813: Postgres db-engine ignores schema information in getDropIndexSql() method