Updating data in a database requires updating the schema
With Type 1, a fact row is simply updated in place.
And with Type 2, the original fact row is end-dated and flagged as logically deleted, then a replacement row is inserted.
If for some reason such manipulations are impractical, simply inserting a nullification of the initial row, and then inserting the replacement row can work too - original "10," insert a negation “-10” row, then insert the replacement ‘9’ row.
Summation queries will always arrive at the correct answer, and defining a query retrieving values as they were at a specific point-in-time becomes relatively easy.
You can think of a repository as a PHP class whose only job is to help you fetch entities of a certain class.
Once you have a repository object, you have many helper methods: If the number of database queries is too high, the icon will turn yellow to indicate that something may not be correct.
query optimizer relies on up-to-date statistics for tables, schemas, and the database.In the data warehousing world, the best practice is to data into every fact table.Not updating fact rows is understood based on the idea that updates are slower than inserts, and that fact tables are generally so large that updating individual rows is an even slower process when looking up the row takes longer.As a matter of perspective, if a circumstance is in place where a fact table is truncated and reloaded every cycle, one may consider that arrangement as a “Type 1” fact.But fortunately, with truncate and reload there is no actual update processing.