Re: XML Schema for PostgreSQL database - Mailing list pgsql-general

Em 14/12/2012 12:21, Merlin Moncure escreveu:

On Thu, Dec 13, 2012 at 5:52 PM, Edson Richter <edsonrichter@hotmail.com> wrote:

Em 13/12/2012 20:10, Merlin Moncure escreveu:

On Thu, Dec 13, 2012 at 1:54 PM, Edson Richter <edsonrichter@hotmail.com>
wrote:

Has anyone created a XML Schema that would represent PostgreSQL database
with all (or at least, major) structures?

no -- furthermore, why would you want to?  what would be the consumer
of this 'schema'?

merlin

I was wondering to create a tool for diagramming and database forward
engineering.

There are already few tools around.

If you know a good diagramming tool able to database diff and forward
engineering (with "ALTER ...", not "DROP and CREATE"), I would like to know
(by today I do use one commercial tool that is feature incomplete:
DbWrench).

Among others, I've considered also:
- Sybase PowerDesigner: too expensive, does not support PostgreSQL 9.1/9.2,
so is not appropriate.
- ERWin: too expensive, and doesn't have proper support for PostgreSQL
9.1/9.2.
- NaviCat: is feature extensive, but they don't have real change scripts
(are drop/create).
- ModelRight: it's "change script" is not change at all (is just another
drop/create tool).
- TORA and other open source tools are really incomplete.
- TOAD is too confuse for simple day-by-day work.

Most of these tools or doesn't support PostgreSQL features (are too
generic), or doesn't do real forward engineer (are only able to drop/create
objects, not alter them), or cannot deal with partial diagrams (I can't deal
with only one diagram with hundred of tables at once).

Years ago I decided that the only way to do forward engineering was to
capture the changes I make to development databases in scripts and to
manually apply those scripts for release management.  This process
works and like you I've found the various commercial tools to have
various weaknesses.  So for forward engineering I say: quit using
tools and write scripts.

Yes, I've developed special tasks to update database automatically based on schema version. But this becomes a hard work very quick (because system grows too fast and we don't have dedicated DBA to deal with all those changes).

I'm also like you amazed how poor the various database diagramming
tools are -- they all suck.  Case Studio used to be pretty good back
in the day but I wouldn't recommend it today.  My personal take on
ERD/diagramming is that:

*) diagram generation should be automatic and useful

Yes - also, tool must have multi diagram support, in order we can organize different views of the structure.

*) human input to adjust the layout should not be required (every time
I move the stupid boxes and straighten the stupid lines I feel like
I'm finger painting)

Yes, I also hate that. DBWrench (tool I use today) has no auto layout of any kind, and I feel like a fool arranging tables when I'm supposed to do something that add value to our customers.

*) diagram tool should follow database changes and adjust the diagram
accordingly

Yes - database diff between database and model design with true change scripts. If I change the name of a column, I do expect "Alter table XXX rename column YYYY to OOO" (or something like that, I can't remember the syntax right now).

*) diagram output should be standard html (only) without requiring
tool to log in and adjust diagram

I don't really care about output - SVG would be excellent, because it scales well and will print nicely.
I can tell that a data dictionary with diagramming output would be enough. If I can edit the data dictionary and system keep track of all changes, would be enough for me.
If PgAdmin would have the ability to maintain a data dictionary that is not the database itself, and plus the feature to "synchronize with database" (which would be any PostgreSQL database registered) would be optimal for me.

I've come around to the point of view that this is an unfilled niche
in the industry.  Furthermore, as long as scope is kept reasonably
down, this is not a very difficult project.  So I've decided (along
with Atri) to give it a shot.  Iniitial plans is to do plain html
dumps directly out of the database and use GraphVis to document
dependency flow.

That was my thought - if it's not too expensive, I can do something. That's my question regarding XML, would be very easy for me to work with it using Java (my preferred language, which I use on daily basis).
XML would work well with versioning systems, and is quite easy to "diff" etc.

If there is anything I can help, let me know.