[Gnumed-devel] tricky (?) mini project

[Karsten Hilbert]

Syan,

maybe I can pique your interest with this ? (Because you
already wrote half of it when writing the schema-to-frontend
generator.)

To write a pg_dump-like utility that creates an SQL script
from a given identity.id value.

The idea:

Given a primary key of a table (say, identity) trawl the schema
graph by following foreign key links stopping branching at A)
already visited tables, B) circular dependancies (which really
is the same as A) and C) predefined stop tables.

The use case:

We would want to be able to programmatically say: "Dump
patient X in a way that can be replayed later in this or
another GNUmed database" (given a matching schema, of course).
This is useful so we can easily and safely migrate patient
data across database bootstraps. It may be a useful foundation
for migrating data on database upgrades.

Considerations:

When replaying this dump file into a database we cannot
guarantee that the original primary keys are still unused.
However, primary keys are not supposed to carry business
meaning. Hence the dump file may be constructed in such a way
that first a new row is created in the "root" table (eg
identity) and the new "root" primary key is gotten from that
and used in the process to write appropriate dependant insert
queries. Likewise with further keyed dependancies ...

Oh, and:

- Preferably client_encoding unicode should be used to cleanly
  get across all text data.
- The dump file should be runnable inside a transaction.

This does not have to be ready in time for 0.1 but must IMO
exist when 0.1+x is released (eg I don't think 0.1+x should
happen without it).

This project is open to anyone else too, of course.

Jim, dare I say "Wiki" ?

Karsten
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