[doc] DB migration mechanism

[Sebastian Birnbach]

Thanks all. I took the liberty to write this down in
http://wiki.horde.org/UpdatingYourDatabaseSchema.

  Sebastian

2014-12-18 9:45 GMT+01:00 Ralf Lang <lang at b1-systems.de>:
>
> Hallo Sebastian, please do not top post but answer inline or below.
>
> On 18.12.2014 09:24, Sebastian Birnbach wrote:
> > Thanks Ralph but this still leaves some questions open.
> >
> > I understand the migration mechanism is provided to allow a DB schema
> > update without losing data.
> >
> > File naming appears to follow this pattern:
> > <n>_<appname>_[base|upgrade]_<name>.php.
> > The class defined in the file must then be called
> > <Appname>[Base|Upgrade]<Name>.
> >
> > Questions:
> > * what is the difference between base and upgrade? If the scripts are
> > always executed in ascending order this difference is not self
> explanatory.
>
> As far as I know, there is no relevant difference. The class name simply
> must match.
>
> > * are there more choices to [base|upgrade]?
> You can call it whatever you want. In an inhouse application, wie simply
> call the <n>_<app>_<changename>.php
>
> > * The admin console appears to detect if a file in migration/ was not
> > executed. However, it does not test if one of the files was modified
> > after last time it was executed, right? So for repeated execution
> > (development) I must use
> > horde-db-migrate <appname> down; horde-db-migrate <appname> up
> Doing "down" runs down through all steps and means data loss. You can
> tell it a target revision.
> The sequence table only stores the current schema number. It does not
> store the applied schema itself.
>
>
> > * speaking of horde-db-migrate, I have some issues there (maybe not the
> > correct mailing list, please forgive)
> >   + upon usage it outputs about 100 warnings, mostly about violated PHP
> > strict standards and the use of deprecated functions.
> This depends on the PHP version and configuration. Horde 5.0 is targeted
> at PHP 5.3.x - If you see any deprecation warning with the latest (git
> or release) horde version on a recent PHP, you should probably open a
> ticket on bugs.horde.org or submit a patch to github.
>
>
> >   + it will run under permissions of any user but only produce
> > meaningful output if run as superuser
> > Is this normal?
>
> I usually always run the horde cli scripts in a non-privileged system
> user. This works for me.
>
> --
> Ralf Lang
> Linux Consultant / Developer
> Tel.: +49-170-6381563
> Mail: lang at b1-systems.de
> B1 Systems GmbH
> Osterfeldstraße 7 / 85088 Vohburg / http://www.b1-systems.de
> GF: Ralph Dehner / Unternehmenssitz: Vohburg / AG: Ingolstadt,HRB 3537
>
>
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