Tag Archives: Aggregate function

I did warn that this blog, might be used to remind myself of things: and this is one.

Inconsistent analysis is a problem with databases when an aggregate function is used on data that is being updated by another transaction eg

T1                                            T2

$\alpha$ =SUM(accounts(4 .. 7))

account(1) = $\alpha$          account(4) = account(4) + 10

account(2) = $\alpha + 5$

By the final line $\alpha$ is out of date (as account 4 has been updated but the SUM total has not).