Обсуждение: audit table

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The documentation says you cannot use a pseudo type for a table column,
so I was wondering if there is any way to handle what I would like to do.

I want a trigger on every table that inserts the old row into an audit
table (for updates and deletes). If the audit table was per table, then
I could easily have a field of type that table and insert old into it.

Is there any way that I could accomplish this functionality with any
other type, so I could input any record into it?

When I read it out, I would obviously cast it out to the correct type.

Sim
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Sim Zacks wrote:

> I want a trigger on every table that inserts the old row into an audit
> table (for updates and deletes). If the audit table was per table, then
> I could easily have a field of type that table and insert old into it.

> Is there any way that I could accomplish this functionality with any
> other type, so I could input any record into it?

You want a single audit table that looks like this:

CREATE TABLE audit (
   id SERIAL PRIMARY KEY,
   table_changed regclass,
   changed_by VARCHAR,
   changed_when TIMESTAMP WITH TIME ZONE,
   oldrow ANY_ROW_TYPE
);

ie you want a field that can dynamically contain anything?

AFAIK that's not possible unless you want to store a textual
representation of the row. I'm not sure of an easy way to do it even
then, and of course you can't read it out again as a real row.

What you might want to look at doing is using table inheritance. Your
master audit table looks like this:

CREATE TABLE audit (
   id SERIAL PRIMARY KEY,
   table_changed regclass,
   changed_by VARCHAR,
   changed_when TIMESTAMP WITH TIME ZONE,
);

and then you have child audit tables for each audited table, each of
which looks like this:

CREATE TABLE audit_tablename (
    old_row tablename;
) INHERITS audit;

--
Craig Ringer

On Thursday 12 February 2009 22:13:05 Craig Ringer wrote:
> Sim Zacks wrote:
> > I want a trigger on every table that inserts the old row into an audit
> > table (for updates and deletes). If the audit table was per table, then
> > I could easily have a field of type that table and insert old into it.
> >
> > Is there any way that I could accomplish this functionality with any
> > other type, so I could input any record into it?
>
> You want a single audit table that looks like this:
>
> CREATE TABLE audit (
>    id SERIAL PRIMARY KEY,
>    table_changed regclass,
>    changed_by VARCHAR,
>    changed_when TIMESTAMP WITH TIME ZONE,
>    oldrow ANY_ROW_TYPE
> );
>
> ie you want a field that can dynamically contain anything?
>
> AFAIK that's not possible unless you want to store a textual
> representation of the row. I'm not sure of an easy way to do it even
> then, and of course you can't read it out again as a real row.
>
> What you might want to look at doing is using table inheritance. Your
> master audit table looks like this:
>
> CREATE TABLE audit (
>    id SERIAL PRIMARY KEY,
>    table_changed regclass,
>    changed_by VARCHAR,
>    changed_when TIMESTAMP WITH TIME ZONE,
> );
>
> and then you have child audit tables for each audited table, each of
> which looks like this:
>
> CREATE TABLE audit_tablename (
>     old_row tablename;
> ) INHERITS audit;
>

http://pgfoundry.org/projects/tablelog/

--
Robert Treat
Conjecture: http://www.xzilla.net
Consulting: http://www.omniti.com