The problem

Imagine a data warehouse where you have many etl process from either a staging area or other external systems direclty.There are also many reading tasks that fill data marts for reporting purposes.

Imagine now you have to update many records because you discovered a bug and you cannot create a maintenance window since the DW has to be online 24/7.

So let us just do the update straight away, right? For that purpose we create a large table i.e. an eample fact table

CREATE TABLE dbo.demotable (
	id INT IDENTITY NOT NULL,
	val1 BIGINT NOT NULL,
	val2 BIGINT NOT NULL,
	val3 BIGINT NOT NULL,
	val4 BIGINT NOT NULL,
	val5 BIGINT NOT NULL,
	val6 BIGINT NOT NULL,
	val7 BIGINT NOT NULL,
	val8 BIGINT NOT NULL,
	val9 BIGINT NOT NULL,
	val10 BIGINT NOT NULL,
	val11 BIGINT NOT NULL,
	val12 BIGINT NOT NULL
);
....

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