Massive Performance Degradation On Statistics For Large Partitioned Tables After Upgrade To 19c (Doc ID 2611336.1)

Last updated on JULY 20, 2024

Applies to:

Symptoms

• In 19c there has been an enhancement with regard to how bit map indexes are treated when statistics are gathered. Ehancement request "BUG 27268249 - ENHANCE INDEX NDK STATISTICS GATHERINGW". In some cases the gathering time for statistics can take longer in the presence of bitmap indexes:  
  12c:

  > select num_rows, sample_size
  2 from dba_ind_statistics where index_name like '<index-name>'
  3 and object_type = 'INDEX';

  NUM_ROWS SAMPLE_SIZE
  ------------------- ---------------
  6132556 14818

  19c:

  > select num_rows, sample_size
  2 from dba_ind_statistics where index_name like '<index-name>'
  3 and object_type = 'INDEX';

  NUM_ROWS SAMPLE_SIZE
  ------------------- ----------------
  6409926 6409926

    

Changes

Enhancement  "BUG 27268249 - ENHANCE INDEX NDK STATISTICS GATHERINGW"

Cause

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.