Document Type | Troubleshooting
Category | Monitoring/Inspection
Applicable Product Versions | 6FS06, 6FS07
Document Number | TMOTS026
Overview
When checked through tbinary, the DD Cache hit ratio (HIT Ratio) is displayed abnormally.
# Partial excerpt from v$rowcache query results (HIT_CNT is negative) ------------------------------------------------------------------------------------------------------------------------------- | NAME | SEARCH_KEY | BUCKETSET_ID | ENTRY_CNT | HIT_CNT | MISS_CNT | CACHE_SIZE | PINNED_CNT | INVALID_CNT | NE_CNT | ------------------------------------------------------------------------------------------------------------------------------- .. | HIST_HEAD | 4 | 2 | 380 | -1892661659 | 3 | 1368 | 0 | 377 | 0 | | HIST_HEAD | 4 | 3 | 2 | 2 | 0 | 0 | 0 | 2 | 0 | | HIST_HEAD | 4 | 4 | 3 | -1169737111 | 1 | 1368 | 0 | 0 | 0 | | HIST_HEAD | 4 | 5 | 3 | -1558438538 | 2 | 1400 | 1 | 0 | 0 | .. -------------------------------------------------------------------------------------------------------------------------------
Cause
When there are many references to the DD Cache, the HIT_CNT value becomes large and causes an OVERFLOW (exceeding the int data type range), resulting in the HIT_CNT value being displayed as negative or abnormally.
Solutions
Method 1. Apply Patch
Apply the patch to resolve the issue. (Applied patch: FS06_CS_173791a)
CautionApply the patch through technical support provided by TmaxTibero.
NoteFS06_CS_173791a Patch InformationExtends hash table hit_cnt and miss_cnt columns (data type change) and modifies related functions
Method 2. Workaround (Temporary)
Restart the DB so that the HIT_CNT value queried from V$ROWCACHE can be reset.
NoteEven if the value is displayed as negative or abnormally, there is no problem within the DB.