tailieunhanh - Oracle Database Administration for Microsoft SQL Server DBAs part 25

Oracle Database Administration for Microsoft SQL Server DBAs part 25 takes the administration topics with which the SQL Server DBA is familiar, translates them into Oracle terms, and then expands on Oracle functionality. Definitions and comparative terms run throughout the book so the SQL Server DBA can easily leverage existing knowledge. This Oracle Press guide also expands on some of the features in Oracle that do not match up directly with SQL Server, and looks at other processes often performed on an Oracle database that would not typically be a standard practice in SQL Server environments | 222 Oracle Database Administration for Microsoft SQL Server DBAs Current Sessions Obviously when there are performance issues it is necessary to take a look at the current sessions on the database. There is no sp_who sp_who2 or sp_lock in Oracle but there is the v session view. This view shows which sessions are active. You can join this with another view to see which queries a session is running. f SQLPLUS select username schemaname osuser lockwait status from v session where status ACTIVE and username not in SYS SYSTEM USERNAME SCHEMANAME OSUSER LOCKWAIT STATUS DBSNMP DBSNMP oracle null ACTIVE MMALCHER MMALCHER mmalcher null ACTIVE USER1 APP1 userl null ACTIVE Lockwait will be a non-null value when waiting on a resource such as a lock or a latch Another view to see this would be v session_wait To see a SQL statement from one of the users currently active SQLPLUS select from v sqlarea sa v sqltext st v session s where and and SCOTT SQL_TEXT INSERT INTO log_messages id service processed_date log_date VALUES SYS_B_0 SYS_B_1 TO_TIMESTAMP SYS_B_2 SYS_B_3 SYS_B_4 TO_DATE SYS_B_5 SYS_B_6 INSERT INTO log_messages id service processed_date log_date VALUES SYS_B_0 SYS_B_1 TO_TIMESTAMP SYS_B_2 SYS_B_3 SYS_B_4 TO_DATE SYS_B_5 SYS_B_6 To see what locks are current on an object SQLPLUS select session_id owner type mode_held mode_requested from dba_ddl_locks SESSION_ID OWNER TYPE MODE_HELD MODE_REQUESTED 871 YELL1 Table Procedure Type Null None 627 SNAP Table Procedure Type Null None 284 SNAP Table Procedure Type Null None 286 ADB Table Procedure Type Null None 357 ADB 18 Null None Chapter 8 Performance and Tuning 223 Activity Monitors In OEM under the Performance tab you ll find additional monitoring links for looking at the top activity instance activity blocking sessions and currently running SQL as shown in Figure 8-1. There are statistics that are gathered as part of the Automatic Workload Repository