Re: Feature request: temporary schemas

On 09/14/2014 08:21 PM, cowwoc wrote:
> Hi Adrian,
>
> Replies below.
>
> On 14/09/2014 8:34 PM, Adrian Klaver wrote:
>> On 09/14/2014 02:01 PM, cowwoc wrote:
>>> See http://dba.stackexchange.com/q/76494/4719 for a related discussion.
>> So from the above link and the discussion here so far I gather you want:
>>
>> 1) A CREATE TEMPORARY SCHEMA that behaves like CREATE TEMPORARY TABLE,
>> where it lasts only for a session and masks any existing schema and
>> contained objects with the same name for the duration.
>
> Yes. Tests should not be able to see each other's tables, data (and
> ideally not even each other's schema).
>
>> 2) You want to run this on a test database as so you can have 'masked'
>> tests over the permanent schema. Presumably because the tests can be
>> destructive and you do not want change the underlying structure and/or
>> data in your test database.
>
> Not exactly. Each test is responsible for populating its own schema
> (creating tables, inserting data). The main purpose of using temporary
> schemas is to ensure that each test runs in isolation so that data from
> other tests cannot influence the outcome of the test. This ensures test
> execution/results are 100% reproducible.

So the tests may or may not have anything to do with the existing test
database?

>
>> 3) This needs to happen on the order of 4-10 times a second and it
>> needs to be tied to a session, as multiple transactions need to be run
>> in each test.
>>
>> As to whether this is the appropriate list, I would say yes at least
>> for sounding out the idea. The list to address for dealing with the
>> folks that actually would implement the idea I would suggest --hackers.
>>
>> In the meantime, the only way I can see doing this is creating and
>> dropping databases. Not sure that would meet your 4-10 times a second
>> requirement though.
>
> One of the requirements is that if someone kills the process running the
> unit tests, it can't leave behind any dangling schemas. I expect all
> test data to get dropped automatically when the connection is closed
> unexpectedly, so DROP DATABASE won't do.

I would think a DROP DATABASE IF EXISTS, CREATE DATABASE at the
beginning of the test would handle that.

>
> Gili
>
>


--
Adrian Klaver
adrian.klaver@aklaver.com