Knobit of Data modelling · K-626 · Skill

Recognises a fact table of mixed grain

What it means

A fact or wide table whose rows mean different things, or whose columns are true at different grains. Measures at the coarser grain repeat on every finer row and are counted again when summed.

How it is assessed

Flags the deficient case and passes the acceptable one. Deficient: `fact_account_balance` with one row per payment carrying `ledger_balance_amount`, which is per account per day: an account with three payments in a day reports three times its balance Acceptable: A grain sentence, and every column true at that grain; `fact_payment` at payment grain and daily balances on `fact_account_balance_daily` (`PHY-013`, `PHY-028`)

Builds on

Explains grain and additivity in dimensional modelsK-659 · Knowledge

Needed by

None