On 3/4/20 2:22 PM, Rory Campbell-Lange wrote:
> On 04/03/20, Adrian Klaver (adrian.klaver@aklaver.com) wrote:
>> On 3/4/20 2:04 PM, Rory Campbell-Lange wrote:
>>> We have many databases of the same type separated for data governance
>>> reasons. They, however, share the same web front-end code.
>>>
>>> Presently, replacing functions and performing data updates on the
>>> databases in series often executes across all databases in less than a
>>> minute. (The updates are currently done with simple sql files connecting
>>> to each database and then loading a stub file pointing to each function
>>> to drop and reload, and running the data update queries.)
>>>
>>> However, for larger updates, the time when the front end code is
>>> out-of-step with the database can cause end-user problems.
>>
>> So the issue is synchronization between the code in the database and the
>> code outside the database?
>>
>> I'm assuming the problems are changes in function signatures and return
>> values?
>
> That is one problem; sometimes we also need to make some table
> definition or data changes.
>
Alright, but the general issue is that the world as seen by the database
can be different from that seen by the front end code.
So the solution is to make those world views sync, or am I missing
something?
>>> Unfortunately our schema arrangement isn't clean enough to swap out
>>> function schemas in a transaction to sort out that part of the problem
>>> (if in fact that would work anyway).
>>>
>>> One solution might be to do the updates in parallel. Another thought
>>> would be to somehow execute the code update from a text field in a table
>>> in each database triggered with pg_cron.
>>>
>>> Bearing in mind the possible problems of connection saturation or
>>> massive IO spikes, I'd be grateful to learn of any thoughts on how to
>>> negotiate this problem.
--
Adrian Klaver
adrian.klaver@aklaver.com