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Tham khảo tài liệu 'oracle database 10g the complete reference phần 7', công nghệ thông tin, cơ sở dữ liệu phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 43 The Hitchhiker s Guide to Tuning Applications and SQL 793 End-to-End Tracing Application end-to-end tracing identifies the source of an excessive workload such as an expensive SQL statement by client identifier service module or action. Workload problems can be identified by client identifier service a group of applications with common attributes application module or action. Service names are set via DBMS_SERVICE.CREATE_SERVICE or the SERVICE_NAMES initialization parameter. Set the module and action names via the SET MODULE and SET ACTION procedures of DBMS_APPLICATION_INFO. The trcsess Utility The trcsess command-line utility consolidates trace information from selected trace files based on specified criteria Session ID Client ID Service name Action name or Module name . Trcsess merges the trace information into a single output file which can then be processed via TKPROF. Optimizer Modifications Within the optimizer the major changes in Oracle Database 10g include Obsolescence of the rule-based optimizer. Changed parameters for the OPTIMIZER_MODE initialization parameter. CHOOSE and RULE are no longer valid ALL_ROWS is the default. Dynamic sampling set via OPTIMIZER_DYNAMIC_SAMPLING now defaults to 2. CPU Costing has been added to the cost calculations. The cost unit is time. New hints available for queries include SPREAD_MIN_ANALYSIS USE_NL_WITH_INDEX QB_NAME NO_QUeRy_TRANSFORMATION NO_USE_NL NO_USE_MERGE NO_USE_HASH NO_INDEX_FFS NO_INDEX_SS NO_STAR_TRANSFORMATION INDEX_SS INDEX_SS_ASC and INDEX_SS_DESC. Hints that have been renamed include NO_PARALLEL formerly NOPARALLEL NO_PARALLEL_INDEX formerly NOPARALLEL_INDEX and NO_REWRITE formerly NOREWRITE . The AND_EQUAL HASH_AJ MERGE_AJ NL_AJ HASH_SJ MERGE_SJ NL_SJ ORDERED_ PREDICATES ROWID and STAR hints have been deprecated and should not be used. Hash-partitioned global indexes can improve performance of indexes where a small number of leaf blocks in the index have high contention in multiuser OLTP .
