>SQL Server: What is an Algebrizer ?
After an interview for DBA post, a friend of mine called me and without saying “Hello”, asked “What is Algebrizer?” Yeah it’s the guy who is always ready to work for you when ever you write a query and press F5 to execute 😉
Algebrizer is a process in query execution, which starts its work after Parser. Once the parser finds query syntax correct, it passes it to the algebrizer. Here start work of algebrizer:
· Algebrizer is responsible for objects and columns names (which you have provided in query or which are being referenced by your query) verification. For example if wrong name for a table is typed in a query, then its algebrizer’s duty to verify and generate an error.
· Algebrizer also identifies all data types which are being processed for a given query.
· Algebrizer verify that GROUP BY and aggregate columns are placed in right place or not. For example if you write following query and just Ctrl+F5 (just to parse). No error will be generated. But when you will press F5 (execute it). After Parsing, algebrizer will work and return an error.
GROUP BY ProductNumber