Document Oracle-specific database settings, esp. for tests.

[Aymeric Augustin]

EDIT: a few days after reporting this ticket, I changed my recommendation. See comments 2 and 3 below. I'm updating the title to reflect this.

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Original title: Don't hardcode the location of Oracle's datafiles for the test tablespaces

Use case: I want to move Oracle's datafiles to a RAM disk (tmpfs) to speed up the execution of Django's test suite.

Problem: django.db.backends.oracle.creation currently uses this SQL: CREATE TABLESPACE %(tblspace)s DATAFILE '%(tblspace)s.dbf' ...

It's allright to provide a datafile name, because we can't assume all users of Django are using Oracle-managed files. However, since we provide a relative path, the file will always be created in Oracle's dbs directory. The DB_CREATE_FILE_DEST parameter is ignored when a datafile name is provided.

See ​http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/clauses004.htm#i1030551 (if you speak Oraclese).

Proposed solution: add an optional setting to control the location of the datafile during the tests. If the setting is not provided, default to TEST_TBLSPACE + '.dbf' for backwards compatibility.

[Aymeric Augustin]

NB: during the test suite, each tablespace takes 160MB (see attached screenshot). This is a good reason to move it to RAM.

[Aymeric Augustin]

Upon further investigation, there are undocumented TEST_CREATE and TEST_USER_CREATE boolean parameters.

The best solution may be to set TEST_CREATE = False and create the tablespace with whatever parameters I want.

[Aymeric Augustin]

Here is a new patch that documents the undocumented Oracle-specific settings. I'm now using this, and I'm creating and dropping the user and the tablespaces with a separate SQL script.