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

774 Locking in the Sybase IQ Interface 4 Chapter 27BL_USE_PIPE=NOBL_SERVER_DATAFILE=’/tmp/fltdata.dat’BL_CLIENT_DATAFILE=’/tmp/fltdata.dat’ )as select * from sasflt.flt98;quit;In this example, you can append the SASFLT.FLT98 SAS data set to the existingSybase IQ table, ALLFLIGHTS. The BL_USE_PIPE=NO option forces SAS/ACCESSInterface to Sybase IQ to write data to a flat file, as specified in the BL_DATAFILE=option. Rather than deleting the data file, BL_DELETE_DATAFILE=NO causes theengine to leave it after the load has completed.proc append base=mydblib.allflights(BULKLOAD=YESBL_DATAFILE=’/tmp/fltdata.dat’BL_USE_PIPE=NOBL_DELETE_DATAFILE=NO)data=sasflt.flt98;run;Locking in the Sybase IQ InterfaceThe following LIBNAME and data set options let you control how the Sybase IQinterface handles locking. For general information about an option, see “LIBNAMEOptions for Relational Databases” on page 92.READ_LOCK_TYPE= ROW | TABLEUPDATE_LOCK_TYPE= ROW | TABLEREAD_ISOLATION_LEVEL= S | RR | RC | RUSybase IQ supports the S, RR, RC, and RU isolation levels that are defined in thistable.Table 27.3Isolation Levels for Sybase IQIsolation LevelS (serializable)RR (repeatable read)RC (read committed)RU (read uncommitted)DefinitionDoes not allow dirty reads, nonrepeatable reads, orphantom reads.Does not allow dirty reads or nonrepeatable reads; doesallow phantom reads.Does not allow dirty reads or nonrepeatable reads; doesallow phantom reads.Allows dirty reads, nonrepeatable reads, and phantomreads.Here are how the terms in the table are defined.Dirty readsA transaction that exhibits this phenomenon has very minimalisolation from concurrent transactions. In fact, it can seechanges that are made by those concurrent transactions evenbefore they commit.