This bug ? (Neither number public)
https://jonathanlewis.wordpress.com/2019/12/16/iot-bug/
- Bug 30733525 – ALERT LOG ENTRIES RE BLOCK GUESSES IN THE SECONDARY
INDEXES OF IOTS POINTING TO OVERFLOW SEGMENT INSTEAD OF INDEX SEGMENT
- Bug 30733563 – WRONG GUESS DBA IN INDEX
Regards
Jonathan Lewis
On Thu, Sep 3, 2020 at 12:49 PM Noveljic Nenad <nenad.noveljic@xxxxxxxxxxxx>
wrote:
The primary reason for the bad performance in 19c with the secondary index
weren’t the obsolete references, as I first speculated.
According to captured stacks, the process was being mostly busy with
spooling blocks into the trace:
00007fff999783da __write () + a
00000000075671ad sdbgrfuwf_write_file () + 3d
000000000756711c sdbgrfwf_write_file () + 3c
000000000754a55d dbgtfdFileWrite () + 20d
00000000074ececf dbgtfdFileAccessCbk () + 19f
000000000756dfe7 dbgtfPutStr () + 2d7
000000000756d75e dbktPri () + ce
00000000074fe039 ksdfmw () + 1e9
00000000077578d0 krvtwdb () + e0
00000000077568a1 kdr4dmp () + c91
000000000775505d kdb4dmp1 () + a8d
00000000077545ac kdb4dmp () + 4c
00000000136f0e37 kdbdmp_full () + 427
00000000136f1b18 kdbdmp () + 38
000000000a4ff05a ktbtdu () + 7a
000000000a4f1d9f ktbdbhw () + 19f
000000000774f69c kcbtdu1 () + 63c
0000000007748e68 kcbzdh () + 2478
000000000624b2c4 kcbzib () + a5a4
000000000628c07c kcbgtcr () + 264c
00000000063511bd ktrgtc2 () + 3dd
000000000634f944 qeilbk1 () + 1b24
000000000634ddde qeilbk0 () + e
0000000017316da1 qerixFetchByLogicalRowid () + 311
000000000c423022 qerstFetch () + 542
00000000067935de rwsfcd () + 6e
000000000c423022 qerstFetch () + 542
0000000017293f7b qerhnFetch () + 56b
000000000c4230a0 qerstFetch () + 5c0
0000000006ba3fd3 qerjoFetch () + 383
000000000c423022 qerstFetch () + 542
00000000067935de rwsfcd () + 6e
000000000c423022 qerstFetch () + 542
00000000172947d4 qerhnFetch () + dc4
000000000c423022 qerstFetch () + 542
00000000064522c2 qervwFetch () + a2
000000000c423022 qerstFetch () + 542
00000000067935de rwsfcd () + 6e
000000000c423022 qerstFetch () + 542
0000000006ba2c96 qerusFetch () + 316
000000000c423022 qerstFetch () + 542
00000000124eb76a UpsOnlyInsertExe () + 27a
0000000006ba24e5 upsexe () + e65
000000000613a7aa opiexe () + 3dda
000000000678dc1a kpoal8 () + b5a
0000000006128c09 opiodr () + 439
0000000006132843 ttcpip () + 5f3
000000000612e23c opitsk () + 9ec
000000000612cd58 opiino () + 4a8
0000000006128c09 opiodr () + 439
00000000061281cf opidrv () + 33f
0000000006127e07 sou2o () + 97
0000000006127c51 opimai_real () + 121
000000000612772b ssthrdmain () + 26b
0000000006127499 main () + a9
000000000778ad44 ???????? ()
The reason is in the trace file: “kcbzib: encounter logical error
ORA-1410, try re-reading from other mirror..”
That looks like the latest mutation of some everlasting IOT bug (see MOS).
The query, though, ran without errors. Presumably, following rowids didn’t
work (notice qerixFetchByLogicalRowid on the stack), but then the execution
felt back on PK lookup.
Rebuilding the index resolved the problem. Still have to see for how long.
By adjusting guessq (alias pct_direct_access) I just avoided the
corrupted index.
Best regards
Nenad
https://nenadnoveljic.com/blog
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