dhis2-devs team mailing list archive

[Lars Helge Øverland <larshelge@xxxxxxxxx>]

Hi Bob,

just to inform - the SQL views are dropped in reversed alphabetical order,
and generated in alphabetical order based on name. This means there is no
"intelligence" around detecting view inter-dependencies, but at least gives
a way to deal with it (make sure that a view which depends on another view
is alphabetically ordered after it).

regards,

Lars



On Mon, Sep 28, 2015 at 1:09 PM, Knut Staring <knutst@xxxxxxxxx> wrote:

> I have a similar problem in 2.19 where backups are not getting generated
> because of sqlviews.
>
> On Mon, Sep 28, 2015 at 11:03 AM, Bob Jolliffe <bobjolliffe@xxxxxxxxx>
> wrote:
>
>> I am not sure if this is an issue which has been fixed in later
>> versions, but we recently chanced upon some odd behaviour in 2.17.
>>
>> On the production system there are a number of views defined (through
>> the sql view interface).  A couple of those views depend on other
>> views.   When resource tables are regenerated the views are dropped
>> and recreated as expected.
>>
>> But ...
>>
>> When we restored an exact backup on to a different database on a new
>> system suddenly the resource table generation was failing because it
>> was failing to delete views which depended on other views.  It seems
>> the natural order was changed on the new sqlview table and so the list
>> of views to be deleted come out in a different order to the source
>> system.
>>
>> So ... either
>>
>> 1.  the problem is fixed on a later version; or
>> 2.  we need to have a "cleverer" way to drop the (potentially
>> interdependent) views; or
>> 3.  we need to maintain some sort of ordering/cascading logic which is
>> restored with the backup; or
>> 4.  we should issue a cautionary note that creating views which depend
>> on other views is potentially fragile.  It might work on one system
>> but cause odd problems on a restored system.
>>
>> Maybe 4 is enough.  Anyway I thought I should raise the issue.  Any
>> thoughts?
>>
>> Bob
>>
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>
>
>
> --
> Knut Staring
> Dept. of Informatics, University of Oslo
> Norway: +4791880522
> Skype: knutstar
> http://dhis2.org
>
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>


-- 
Lars Helge Øverland
Lead developer, DHIS 2
University of Oslo
Skype: larshelgeoverland
http://www.dhis2.org <https://www.dhis2.org>