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High row cache lock when drop user tables

Mr.D.Feb 12 2024 — edited Feb 12 2024

Hi,

I get a high row cache lock when dropping user tables.
From AWR:

Total Wait Wait % DB Wait
Event Waits Time (sec) Avg(ms) time Class
------------------------------ ----------- ---------- ---------- ------ --------
row cache lock 8,356,285 6638.5 0.79 24.9 Concurre
db file sequential read 1,811,710 5085.8 2.81 19.1 User I/O
reliable message 702,664 3207.6 4.56 12.1 Other
DB CPU 1846.5 6.9

Cache id="16" -→ dc_histogram_defs
mode="0"
request="5"

                                   Get    Pct    Scan   Pct      Mod      Final
Cache                         Requests   Miss    Reqs  Miss     Reqs      Usage
------------------------- ------------ ------ ------- ----- -------- ----------
dc_awr_control                     489    2.0       0   N/A        4          1
dc_constraints                     557  100.0       0   N/A      557          0
dc_files                         2,236    0.0       0   N/A        0        172
dc_global_oids                   6,687    1.3       0   N/A       67         91
dc_histogram_data              135,848    6.2       0   N/A    7,133     11,452
dc_histogram_defs            7,712,973   95.1       0   N/A   21,316      7,990
dc_object_grants                   614   13.4       0   N/A        0        241
dc_objects                  68,585,356    0.5       0   N/A  360,523     10,783
dc_profiles                          4    0.0       0   N/A        0          1
dc_props                        40,814    0.0       0   N/A        0         60

Database version: 12.1.0.2.0
Operating system: AIX

Any ideas?

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Added on Feb 12 2024
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