This is a first implementation, EXPLAIN is highly
dependent on the database and I have made some
compromises.

On one hand, the method allows you to run the most
common EXPLAIN and that's it. If you want EXPLAIN
ANALYZE in PostgreSQL you need to do it by hand.

On the other hand, I've tried to construct a string
as close as possible to the ones built by the
respective shells. The rationale is that IMO the
user should feel at home with the output and
recognize it at first sight. Per database.

I don't know whether this implementation is going
to work well. Let's see whether people like it.

Postgres: Do not attempt to deallocate a statement if the connection is no longer active.

Add tests for prepared statements with multiple schemas in
postgreSQL.

* https://github.com/rails/rails:
  Postgresql adapter: added current_schema check for table_exists?
  Postgresql adapter: added current_schema check for table_exists?

Also, move the utils test into its own test case.

Move the private method #extract_schema_and_table into a separate
Utils module so that it can be tested without resorting to #send.

* amongst other things, allows meta_search to run against view-backed models

* add/cleanup tests

* tidy test code and fix my typo 

* table_exists? scoped by schema search path unless schema is explicitly named. Added tests and doc to clarify the behaviour
* extract_schema_and_table tests and implementation extended to cover all cases
* primary_key does not ignore schema information
* add current_schema and schema_exists? methods
* more robust table referencing in insert_sql and sql_for_insert methods

Fix a couple of helper requires that were missed. This was causing the tests to fail to run on 1.8.7.

Refactor Active Record test connection setup. Please see the RUNNING_UNIT_TESTS file for details, but essentially you can now configure things in test/config.yml. You can also run tests directly via the command line, e.g. ruby path/to/test.rb (no rake needed, uses default db connection from test/config.yml). This will help us fix the CI by enabling us to isolate the different Rails versions to different databases.

Applied Patch from https://rails.lighthouseapp.com/projects/8994/tickets/5577-suport-from-tsvector-data-type-in-postgresql

index dump should not include full text indexes. Thanks Ken Mayer for the original patch! [#4949 state:resolved]
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>