Re: approach to upgrading

On May 11, 9:58 pm, Jeff Kish <jeff.k...@xxxxxxx> wrote:
Hi.

I'm not terribly familiar with JDBC but I'm willing to dive in.

I'm considering writing a database upgrade java application for an app that
runs on a couple of major relational db's.

I think I might be able to get away with using jdbc and metadata to do this..
but I think my basic approach might be:
- get table names
- copy tables to change to new name
- fix data and structure of new named tables
- rename exisiting tables to old name
- rename new named tables to existing names

The modifications are to the structure ( column lengths mostly) and to some
data in some primary key fields.

Any pointers, or approach suggestions are appreciated.

thanks
Jeff
Jeff Kish


I would avoid copying tables if at all possible. in stead, it's better
to adopt an approach of only making schema changes that go forward -
i.e. adding new objects, increasing column sizes (but not decreasing
them), adding only nullable columns or columns with default values
etc.

copying data may require extra space, which will slow it down, and
actually may fail you if the DBA hasn't allocated 2x disk space to the
DB.

also, you may want to make sure a current backup exists (some vendors
let you check that - but not in a standard way), or perhaps consider
adding a backup step to your own app.

hope this helps
T

.

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