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Improvement of the logic in the SELECT * FROM _DD_TS WHERE TS_ID = :"SYS_B_0" statement

Document Type | Troubleshooting

Category | Monitoring/Inspection

Applicable Product Versions | 6FS06, 6FS07

Document Number | TMOTS008

 

Issue

There is a phenomenon where performance degradation occurs due to unnecessary access to _DD_TS.
As a result of TPR analysis, the query SELECT * FROM _DD_TS WHERE TS_ID = :"SYS_B_0" appeared as a top item.
This query is internally executed when retrieving segment information or calculating extent size.
 
 

Cause

When retrieving segment information or calculating extent size, there is logic that checks the offline status of the tablespace through _DD_TS. However, under heavy load situations, this logic is repeatedly executed, causing unnecessary resource consumption and performance degradation.
 
 

Solutions

Performance is improved by applying a patch that modifies the logic to refer to the control file instead of querying _DD_TS when checking the tablespace status.
  • FS07_275850b: Modified the logic that checks tablespace offline status when calculating get next extsize
  • FS07_282568a: Modified the logic that checks tablespace offline status when retrieving segment information
Caution
Apply the patch through technical support provided by Tmax Tibero.
Note
Below are cases where the query SELECT * FROM _DD_TS WHERE TS_ID = :"SYS_B_0" is used.
  • Querying the dba_tables view
  • Querying the dba_segments view
  • Adding an extent
  • Querying the next extent
  • Segment creation during Direct Path
  • Querying the number of extent blocks
 
 
 

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