Updating table variables sql 2016
The second argument’s value must match the type column in Temporary table names are prefixed with a number symbol (#).A temporary table is owned by the creating session and visible only to it.
Also, certain types of modifications against objects in tempdb (mainly INSERT and UPDATE operations on heap and LOB data) can benefit from optimized logging: because you don’t need to run a redo phase from the log (roll forward transactions that were committed after the last checkpoint) only the value before the change needs to be recorded in the log—not the value after the change.Later in the chapter I’ll provide more details about working with tempdb.One reason to use a temporary table is to take the load off of a user database when you need to persist temporary data.are just one solution; other ways for handling an independent physical or logical materialization of a set include table variables and table expressions such as views, inline user-defined functions (UDFs), derived tables, and common table expressions (CTEs).You might need to physically persist interim states of your data for performance reasons, or just as a staging area.I’ll also describe global temporary tables, but these typically have different uses than local temporary tables.
I’ll start with some fundamentals of local temporary tables before showing examples, and I’ll do the same whenever discussing a new temporary object type.
Furthermore, temporary tables and table variables are often misused because of lack of knowledge of efficient set-based programming.
In this chapter, I will try to provide you with a clear picture of how the different temporary object types behave, in which circumstances you should use each, and whether you should use them at all.
Also, SQL Server supports a deferred drop feature in tempdb.
When the application drops a large temporary table SQL Servers defers the drop activity to a background thread, so the application can continue working immediately.
They have physical representation in tempdb, although when they’re small enough and Microsoft SQL Server has enough memory to spare, their pages reside in cache.