Oracle Performance Insights A Blog By Kamlesh Ambre

  Introduction Oracle Database 23ai introduced a powerful new diagnostic capability through the DBMS_SQLDIAG.REPORT_SQL function, which generates comprehensive HTML diagnostic reports for SQL statements. The great news for Oracle 19c users is that this feature has been backported to Oracle Database 19.28 , allowing you to leverage advanced SQL analysis without upgrading to 23ai. Before this feature, DBAs typically relied on the awrsqrpt.sql script to analyze SQL execution plans and performance metrics. The new REPORT_SQL function provides a more comprehensive, graphical HTML report with deeper performance insights. What Does SQL Diagnostic Report Provide? The REPORT_SQL function generates a comprehensive HTML diagnostic report that includes: Execution Plan History - Track how execution plans have evolved over time Cursor Sharing Information - Understand cursor behavior and sharing patterns Optimizer Statistics History - View changes in optimizer statistics Index ...

  Introduction:   A recent upgrade from version 19.21 left a customer grappling with a perplexing performance decline, marked by a surge in "free buffer waits." Tasks that once took a manageable two hours were suddenly stretching beyond the tolerable 10-hour mark, prompting a closer examination of the underlying issues. The customer had implemented a multi-tenant architecture utilizing a single Pluggable Database (PDB).   Unveiling the Culprit:   The initial investigation pinpointed a conspicuous increase in "free buffer waits," casting a shadow on system efficiency and causing disruptions in the normal flow of operations. Recognizing the critical nature of this bottleneck, the focus shifted to conducting a thorough hanganalyze to unravel the intricacies of the problem. Chains most likely to have caused the hang:   [a] Chain 1 Signature: 'rdbms ipc message'<='free buffer waits'       Chain 1 Signature Hash: 0x8e1d98d...