G
George Potemkin
Guest
I has asked because our customer sent me statistics gathered while running ATM test and the bottleneck was EXCLWAIT for a first block on RM chain of the history table. 100+ of 150 processes were waiting in buffer lock queue. DB Buf X Lock: 24368 requests/sec, 6532 waits/sec (27% of requests). At any snapshots only 10% of transactions were in Active status, 8% - in Phase 2 and the rest 82% in Begin status. I guess we would get the similar results running the readprobe test where readalot.p would consist of one line: NEXT-VALUE(Next-Cust-Num). The number of sequence updates per sec (= SEQ latch locks / 2) would match the number of records created by atm test in the history table while the test with a sequence does not ever create the transactions. That is why I believe atm test should use many copies of the history table. Unfortunately I can't verify my "theory" in my own tests.
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