SAS/ACCESS 9.2 for Relational Databases: Reference, Fourth Edition

812 Teradata Processing Tips for SAS Users 4 Chapter 28do x=2001 to 3000;output;end;run;/* Append the SAS data to the Teradata table. */proc append data=work.testdata base=trlib.mlfload(MultiLoad=yes);run;This example loads data using TPT FastLoad./* Check the SAS log for this message to verify that the TPT API was used.NOTE: Teradata connection: TPT Fastload has inserted 100 rows.*/data trlib.load(TPT=YES FASTLOAD=YES);do x=1 to 1000;output;end;run;This example restarts a MultiLoad step that recorded checkpoints and failed afterloading 2000 rows of data.proc append data=trlib.load(TPT=YES MULTILOAD=YESTPT_RESTART=YES TPT_CHECKPOINT_DATA=2000)data=work.inputdata(FIRSTOBS=2001);run;Teradata Processing Tips for SAS UsersReading from and Inserting to the Same Teradata TableIf you use SAS/ACCESS to read rows from a Teradata table and then attempt toinsert these rows into the same table, you can hang (suspend) your SAS session.Here is what happens:3 a SAS/ACCESS connection requests a standard Teradata READ lock for the readoperation.3 a SAS/ACCESS connection then requests a standard Teradata WRITE lock for theinsert operation.3 the WRITE lock request suspends because the read connection already holds aREAD lock on the table. Consequently, your SAS session hangs (is suspended).Here is what happens in the next example:3 SAS/ACCESS creates a read connection to Teradata to fetch the rows selected(select *) from TRA.SAMETABLE, requiring a standard Teradata READ lock;Teradata issues a READ lock.3 SAS/ACCESS creates an insert connection to Teradata to insert the rows intoTRA.SAMETABLE, requiring a standard Teradata WRITE lock. But the WRITElock request suspends because the table is locked already by the READ lock.3 Your SAS/ACCESS session hangs.