Decision
You don't count the herd while it's moving. You count it once it settles.
A reconciliation test kept flagging mismatches that weren't data errors — it was measuring the gap between when the data was copied and when it was checked.
Blog
Decision
The exchange rate isn't just a dimension. It's part of the fact.
Converting currency at query time gives you the right number and is still the wrong architecture.
Decision
The model migrates. The reasoning doesn't.
The same table that was right on-premises turns expensive in the cloud, and the model never changed.
Governance
A copy doesn't have opinions
Why storing only balance changes isn't enough for month-end reporting — the fix isn't one table doing both jobs, it's two layers with different jobs: the one that copies and the one that answers.
Decision
Average balance isn't calculated. It's captured.
Why daily average balance in banking can't be rebuilt after the fact — the real decision was choosing which accrual tables to snapshot daily, knowing the cost is permanent.