[perlgeek]

> They took great pains to keep data in sync across A and B datastores and I'm not so sure that extra cost was worth the perceived stability of this approach.

Such great pains come with huge systems. What's the alternative?

Taking the platform offline for a few hours? Management will say no. Or maybe Management will say yes once every three years, severely limiting your ability to refactor.

Doing a quick copy, and hope nobody complains about inconsistencies? Their reputation would suffer severely.

[mighty_warrior]

They maintained a replication process across both tables as they updated the read processes before updating the write process. Say for whatever reason their offline replication process broke for 2 hours. For those 2 hours of downtime that replication is broken, the system is reading from a table that is not in sync with the table that is receiving writes. At that point you are displaying incorrect subscription data to your customers.

[sorkin2]

> They maintained a replication process across both tables as they updated the read processes before updating the write process. Say for whatever reason their offline replication process broke for 2 hours.

From the article I got the impression that both tables were being written to in the same database transaction, so this is not a possible failure scenario at all.