Multiple Concurrent Sessions Executing Same DML Statement Runs Slow with High "Read By Other Sessions"' Waits
(Doc ID 2346988.1)
Last updated on NOVEMBER 04, 2019
Applies to:Oracle Database - Enterprise Edition - Version 220.127.116.11 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
- High waits for read by other sessions when multiple concurrent sessions running the same DML statement
- ASH report shows delete statement with high read by other sessions:
DELETE FROM TEST WHERE created_date < (to_date ('2017-12-20 00:00:00') - 15) AND rowid between :start_id and :end_id
48,50467 9.15 read by other session 8.89 UserID: 154 email@example.com (J006) 697/720 [ 97%] 5
291,37525 9.15 read by other session 8.89 UserID: 154 firstname.lastname@example.org (J007) 697/720 [ 97%] 5
578,52933 9.15 read by other session 8.96 UserID: 154 email@example.com (J008) 702/720 [ 98%] 5
866,35684 9.15 read by other session 5.07 UserID: 154 firstname.lastname@example.org (J000) 397/720 [ 55%] 4
874,59167 9.15 read by other session 8.95 UserID: 154 email@example.com (J009) 701/720 [ 97%] 4
- ASH report shows waits are for the index on the table:
Top SQL with Top Events
xxxxxxxxx 1614432425 70 92.94 read by other session 81.29 INDEX - RANGE SCAN 81.29 DELETE FROM TEST... ORCL
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