Обсуждение: metadata development

On Fri, Mar 27, 2009 at 9:44 AM, Dara Olson <dolson@glifwc.org> wrote:
> Happy spring.
>
> I am new to postgres/postgis and am trying to figure out the best way to
> approach documenting metadata within postgres.  Has there been anything
> developed to add FGDC or Dublin Core standard metadata records into postgres
> for each table within the database?  Is there any program that can access
> postgres to insert metadata based on a standard or any other way to document
> metadata for a postgres database?  Any help, suggestions or advice from
> prior experiences would be greatly appreciated.

It's already defined within the database, both in the pg_xxx series of
tables and with the information_schema.  Not sure what you need
besides that , as I'm not familiar with FGDC or Dublin Core standards.

On Fri, 2009-03-27 at 10:44 -0500, Dara Olson wrote:

> I am new to postgres/postgis and am trying to figure out the best way
> to approach documenting metadata within postgres.  Has there been
> anything developed to add FGDC or Dublin Core standard metadata
> records into postgres for each table within the database?  Is there
> any program that can access postgres to insert metadata based on a
> standard or any other way to document metadata for a postgres
> database?  Any help, suggestions or advice from prior experiences
> would be greatly appreciated.

The only way we have of adding additional metadata onto an object is via
the COMMENT command, which accepts a text string as input.

You can fill that with metadata as much as you like - the system never
touches that information other than to store it. So you can put an XML
fragment with Dublin Core tags in there etc.

I think your suggestion that we should have a/another field to store
structured metadata about objects is a good one. It would certainly
encourage better documentation in-database. Perhaps as an additional XML
column.

--
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support

Dara Olson wrote:
>
> Happy spring.
>
> I am new to postgres/postgis and am trying to figure out the best way
> to approach documenting metadata within postgres.  Has there been
> anything developed to add FGDC or Dublin Core standard metadata
> records into postgres for each table within the database?  Is there
> any program that can access postgres to insert metadata based on a
> standard or any other way to document metadata for a postgres
> database?  Any help, suggestions or advice from prior experiences
> would be greatly appreciated.
>
> Thanks in advance.
>
> Dara
>
I'm curious how this would be useful. Why would you want to associate
that sort of information with tables as metadata? Dublin core is a
metadata standard for "information resources" like documents (Tile,
Creator, Publisher, Author, Rights, etc), and FGDC is Geographic data. I
can easily imagine wanting to store such information in your database
using actual tables, as information about "entities" represented in your
database schema, but I don't think attaching it as metadata to a table
is really an appropriate solution. But I don't understand the scenario
you have in mind, and perhaps you could explain the scenario where this
makes sense.

I suspect you are reaching for database metadata simply because these
standards are often described as metadata; but these are usages of the
word "metadata" in very different contexts. What is called metadata in
many contexts is simply becomes data from the context of using a
relational database to represent it.

Eric

MG>(hopefully quick) comments below..

> From: subscriber@blackbrook.org
> CC: pgsql-general@postgresql.org
> Subject: Re: [GENERAL] metadata development
>
> Dara Olson wrote:
> >
> > Happy spring.
MG>Happy Spring..

> >
> > I am new to postgres/postgis and am trying to figure out the best way
> > to approach documenting metadata within postgres. Has there been
> > anything developed to add FGDC or Dublin Core standard metadata
> > records into postgres for each table within the database? Is there
> > any program that can access postgres to insert metadata based on a
> > standard or any other way to document metadata for a postgres
> > database? Any help, suggestions or advice from prior experiences
> > would be greatly appreciated.
> >
> > Thanks in advance.
> >
> > Dara
> >
> I'm curious how this would be useful. Why would you want to associate
> that sort of information with tables as metadata? Dublin core is a
> metadata standard for "information resources" like documents (Tile,
> Creator, Publisher, Author, Rights, etc), and FGDC is Geographic data. I
MG>In that case you would want to look at PostGIS which will create/geo-encode/address-MG>decode GIS Spatial entities contained within polygon/sphere/circle
MG>http://postgis.refractions.net
MG>As the postgis library covers volumes of information please feel free to email me offline

> can easily imagine wanting to store such information in your database
> using actual tables, as information about "entities" represented in your
> database schema, but I don't think attaching it as metadata to a table
> is really an appropriate solution. But I don't understand the scenario
> you have in mind, and perhaps you could explain the scenario where this
> makes sense.
MG>Thus the reason for accessing Database information schema
MG>http://www.alberton.info/postgresql_meta_info.html

> I suspect you are reaching for database metadata simply because these
> standards are often described as metadata; but these are usages of the
> word "metadata" in very different contexts. What is called metadata in
> many contexts is simply becomes data from the context of using a
> relational database to represent it.
MG>metadata means the Data which represents the structure of the referring entity
MG>in a PostGIS system metadata would be SpatialID, ESRI codes and so forth
MG>In a document centric system you would need to understand Templates,Formats
MG>and or stylesheets (to apply to a renderer to produce the document)
MG>In a Secure Enterprise System a document might require specific permissions
MG>such as what a Clinical Investigator might require for a drug study
MG>An example of a comprehensive secure enterprise system please refer to
MG>http://www.oracle.com/industries/life_sciences/oracle-clinical.html

> Eric
MG>Martin
>
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