Useful MOS links in 12c

Things to Consider Before Upgrading to 11.2.0.4 to Avoid Poor Performance or Wrong Results (Document 1645862.1)

Things to Consider Before Upgrading to 11.2.0.3 to Avoid Poor Performance or Wrong Results (Document 1392633.1)

Things to Consider Before Upgrading to 11.2.0.2 to Avoid Poor Performance or Wrong Results (Document 1320966.1)

Things to Consider to Avoid Poor Performance or Wrong Results on 12.1.0.2 (Doc ID 2034610.1)

Wrong Results for a Query When "_ROWSETS_ENABLED" = TRUE (Doc ID 2079913.1)

Things to Consider Before Upgrading to Avoid Poor Performance, Wrong Results or SQL Plan Management (SPM) Issues (11.2.0.X and above) (Doc ID 1904820.1)

Patches to Consider for 12.1.0.2 to Avoid Problems with SQL Plan Management (SPM) (Doc ID 2035898.1)

Note. 2002089.1 High "Latch Free" Waits with Contention on 'Result Cache: RC Latch' when RESULT_CACHE_MODE = MANUAL on Oracle 12c

這個是12c 常見的bug , 在AWR 報告會看到大量的latch free 事件

修改相關參數, 關閉adative dynamic sampling功能後, 發現效能就正常了~

SQL>

alter system set "_optimizer_ads_use_result_cache" = FALSE;

參考連結

https://dban00b.wordpress.com/