Feedback on live schema changes and updates for PostgreSQL

Hello,

We have been developing a high-availability and
version control solution for Postgres, called
ChronicDB[1], that aims to combine live schema
changes, replication, live connection migration,
and scalability in a cohesive manner. We are
requesting feedback[2] on the most desireable
features Postgres users would like to have in such
a solution.

ChronicDB is available for Postgres 7.4, 8.x, and
9, and can already apply live schema changes with
zero downtime through live query-rewritting and
live connection migration. The vision for
ChronicDB is to eventually be able to apply:

Complex live schema changes:
- Partition operations such as vertical and
horizontal splitting
- Field merge and splitting operations
- Field renaming
- Field relocation to a different table
- Table renaming
- All these operations applied together
atomically, without downtime
- Allowing an old version and a new version of an
application to run concurrently, indefinitely
- Reversing schema changes

Replication:
- Master/slave replication, with an unlimited
number of slaves
- Not having to restart replication when 95% of a
database is replicated over a WAN link and a
timeout interrupts replication
- Synchronous replication between a master and a
primary backup
- Hot swap of master with primary backup without
downtime
- Simple configuration

Live connection migration:
- The client applications will not be interrupted,
and won't need to reconnect; downtime will be
eliminated

Scalability:
- Live query inspection and routing to read-only
replicas. This assumes the application is capable
of handling such a weaker consistency model.

We would like to invite you to learn more about
ChronicDB, to download it and to request new
features. We would like to ask:
(1) What are the major types of schema changes you
need to be able to apply ?
(2) If it was possible for us to fix a single (or
two) frustrating, database update problems, which
problems would those be?
(3) What is the major cause of downtime in your
database applications ?

References:
[1] http://chronicdb.com
[2] http://chronicdb.com/request_new_features

Sincerely,

ChronicDB Community Team

http://chronicdb.com/benefits_of_chronicdb