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ENQ: UL CONTENTION FOR HIGH CONCURRENCY ON TEXT INDEX WITH "SYNC ON COMMIT" (Doc ID 2758088.1)

Last updated on MARCH 05, 2021

Applies to:

Oracle Text - Version 12.2.0.1 to 12.2.0.1 [Release 12.2]
Information in this document applies to any platform.

Symptoms

Lots of sessions waiting a long time with event "enq: UL - contention".

Below is the statement being waited on in those sessions:

begin ctxsys.drvdml.com_sync_index(:idxname, :idxmem, :partname); end;

This is confirmed by the AWR report:

Top 10 Foreground Events by Total Wait Time

Event Waits Total Wait Time (sec) Avg Wait % DB time Wait Class
enq: UL - contention 79,851 122,3K 1531.06ms 94.5 Application
DB CPU 6363,6 4.9
log file sync 43,669 532,4 12.19ms .4 Commit
PGA memory operation 1,200,317 273,3 227.72us .2 Other
enq: TX - row lock contention 50,445 138,2 2.74ms .1 Application
direct path read 107,333 51,6 481.06us .0 User I/O
db file sequential read 8,800 42,7 4.85ms .0 User I/O
Failed Logon Delay 25 25 1000.09ms .0 Other
SQL*Net vector data to client 165,705 20,3 122.70us .0 Network
latch free 438 17,3 39.60ms .0 Other


Top SQL with Top Events

SQL ID Plan Hash Executions % Activity Event % Event Top Row Source % Row Source SQL Text Container Name
ddr8uck5s5kp3 11943 96.81 enq: UL - contention 93.39 ** Row Source Not Available ** 93.39 begin ctxsys.drvdml.com_sync_i... NDPRF_OIG
ddr8uck5s5kp3 11943 96.81 CPU + Wait for CPU 3.42 ** Row Source Not Available ** 3.42 begin ctxsys.drvdml.com_sync_i... NDPRF_OIG

Changes

 

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References


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