Writing Analytics SQL with Common Table Expressions

[chubot]

http://research.neustar.biz/2014/05/19/writing-analytics-sql-with-common-table-expressions/

[groovy2shoes]

Some RDBMSs support recursive CTEs, which come in handy sometimes. SQLite added support earlier this year, and I've written a handful of recursive CTEs to traverse DAGs in the database. I was blown away by how quickly SQLite can handle queries like that!

[Xophmeister → groovy2shoes]

Recursive CTEs are part of the SQL:1999 standard and actually make SQL into Turing complete language. I didn't realise SQLite had implemented CTEs, let alone recursive ones...I'll have to play :)

[batbomb → groovy2shoes]

A few others: SQLite, Oracle, PostgreSQL, DB2, HSQLDB.

[yangyang → batbomb]

And SQL Server.

[collyw → yangyang]

Everything except MySQL?

[benilov]

DbFit (http://dbfit.github.io/dbfit/) provides a more heavy-weight, but much more scalable alternative to raw SQL for testing CTEs.

[j_s]

In SQL Server, CTEs eventually slow down then temp tables win because they can have indexes.