Oracle Performance Insights A Blog By Kamlesh Ambre

  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...