SQL ( Structured Query Language ) is the language used to communicate with databases. In Teradata the sql received by Teradata Engine will process in below sequence.

At Parsing Engine :

Step 1 Parser :

The Parser looks the sql request in the Request cache to determine if the request is already available or not 

If the request is available : Reuses the plastic steps found in the cache and passes them to gnc Apply. Go to step 8 after validating privileges (step 4). Plastic steps are prescriptions to the database management system that do not contain data values. 

Plastic advances are mandates to the database the board framework that don't contain information esteems. 

If the request is not available: begin processing the request with the syntaxer.

Step 2 Syntaxer :

The syntaxer validates the syntax of an incoming request. 

No errors : Converts the request into parse tree and passes it to the Resolver.

Errors : Passes an error message back to the requester and stops.

Step 3 Resolver :

The Resolver resolves information from the Data Dictionary (or cached copy of the information) to convert database, table, view, stored procedure, and macro names to internal identifiers. 

Valid : passes the request to the Optimizer.

Not valid : abruptly stops the request and passes an error message and stops.

Step 4 Security check:

The security module checks access rights for the request in the Data Dictionary.

Step 5 Optimizer :

The Optimizer determines the most shortest way to implement the SQL request.

Step 6 :

The Optimizer scans the request to determine where locks should be placed, then passes the optimized parse tree to the Generator.

Step 7 Generator :

The Generator changes the improved parse tree into plastic steps and passes them to gncApply.

Step 8 gncApply :

gncApply takes the plastic steps generated by the Generator and transforms them into concrete steps. Concrete steps are the bible to the AMPs that contain any needed user or session-specific values and any needed data parcels.

Step 9 :

gncApply passes the concrete steps to the Dispatcher.


The Teradata Engine will apply hashing to the request of the rows and find the AMPS in the HASH Map.

At AMPs:

The request will be sent to AMPS via BYNET to fetch or Insert the rows in to Vdisks.