RE: IOT index costing in 19c

From: Noveljic Nenad <>
Date: Thu, 3 Sep 2020 11:48:15 +0000
Message-ID: <>

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


Please consider the environment before printing this e-mail. Bitte denken Sie an die Umwelt, bevor Sie dieses E-Mail drucken.

<html xmlns="">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css">p { font-family: Arial;font-size:9pt }</style>
<br>Important Notice</br>
<br />
This message is intended only for the individual named. It may contain confidential or privileged information. If you are not the named addressee you should in particular not disseminate, distribute, modify or copy this e-mail. Please notify the sender immediately by e-mail, if you have received this message by mistake and delete it from your system.<br /> Without prejudice to any contractual agreements between you and us which shall prevail in any case, we take it as your authorization to correspond with you by e-mail if you send us messages by e-mail. However, we reserve the right not to execute orders and instructions transmitted by e-mail at any time and without further explanation.<br /> E-mail transmission may not be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete. Also processing of incoming e-mails cannot be guaranteed. All liability of Vontobel Holding Ltd. and any of its affiliates (hereinafter collectively referred to as "Vontobel Group") for any damages resulting from e-mail use is excluded. You are advised that urgent and time sensitive messages should not be sent by e-mail and if verification is required please request a printed version.</br> Please note that all e-mail communications to and from the Vontobel Group are subject to electronic storage and review by Vontobel Group. Unless stated to the contrary and without prejudice to any contractual agreements between you and Vontobel Group which shall prevail in any case, e-mail-communication is for informational purposes only and is not intended as an offer or solicitation for the purchase or sale of any financial instrument or as an official confirmation of any transaction.<br /> The legal basis for the processing of your personal data is the legitimate interest to develop a commercial relationship with you, as well as your consent to forward you commercial communications. You can exercise, at any time and under the terms established under current regulation, your rights. If you prefer not to receive any further communications, please contact your client relationship manager if you are a client of Vontobel Group or notify the sender. Please note for an exact reference to the affected group entity the corporate e-mail signature. For further information about data privacy at Vontobel Group please consult <a href=""></a>.<br />

Received on Thu Sep 03 2020 - 13:48:15 CEST

Original text of this message