0.Oracle 十个神秘问题(36 ).pptVIP

Oracle RDBMS10个神秘问题 赵元杰 2008.03.16 Zyj5681@ Ten Database MysteriesChris LawsonDatabase Specialists, Inc.clawson@ Focus of Presentation Explore some “strange” database problems that have baffled some DBAs Most of the mysteries occurred on critical production systems, although some were on development systems ALL of the mysteries were eventually explained Depending on your personal experience, some of these “mysteries” will seem trivial or commonplace; others will indeed seem mysterious Most mysteries have a simple explanation Most mysteries have a simple fix 为什么花时间在这些问题? Each DBA has a unique set of experiences and biases. What one DBA thinks is obvious, another will not. An Oracle “detective” is part scientist, part artist. Many solutions require creativity, not just logic. A superior DBA will look for ways to “stretch” and learn ways to handle difficult problems. Without working out difficult problems, you will not advance as a DBA. You will be the “hero” if you encounter a mystery and solve it; remember the solution--you may see it again! 关于Oracle版本 This presentation was originally written in 1998 Most of these mysteries involve Oracle 7 databases Although some of the mysteries might not apply directly to Oracle 8i, they still offer insight into the problem-solving process 疯狂的应用案例 Clue #1: “Big Phone Company” 1997 Using HPUX, Oracle Help desk application (Vantive) that connects to Oracle database suddenly goes berserk, creating thousands of connections Program had worked normally for many months DBAs watch helplessly as CPU load driven from 1 to 50 As DBAs kill extra processes, more take their place Alert log and recent trace files show nothing unusual DBAs are united in accusing the application as the culprit 疯狂的应用 Clue #2: “Big Publisher Ltd.” 1998 Running Sun Solaris, Oracle Users complain that performance has degraded in recent months Manager states that “something must be wrong with the network” Application is CORIS, a document management/printing