Interleave tables

- [Narrator] The next concept…in properly modeling for Spanner…is this idea of interleave,…or interleaving, multiple tables.…This is as important as a primary key.…So I'm gonna take a minute to clearly explain it.…First of all, foreign keys are not supported in Spanner.…Don't shoot the messenger.…I'm only reporting the news.…So how the heck do you optimize for joins?…Typically of course,…we put foreign keys and indexes on foreign keys,…and that causes the data to be duplicated…so the join is run efficiently.…

It's really a similar concept,…it's just kind of a different name.…So first of all, there are no foreign keys.…Secondly, if we are going to…have join queries running against related tables,…very typical in highly normalized relational databases,…so customers and their orders,…orders and the order details,…so on and so forth,…it's a parent child relationship between multiple tables.…Then when you model,…you indicate to Cloud Spanner…that you wanna physically colocate…the rows for efficient retrieval,…particularly joins using the interleave command…