How Can Improve On Slow Update Query Using /*+ NO_XML_DML_REWRITE */?

Question

We have an update query recently brought to my attention that is running extremely slow on Oracle 11.2.0.1 against a secure file binary XML table using
update /*+ NO_XML_DML_REWRITE */croutreach.action set object_value = :1 where actn_id = :2 .
I am told the majority/near majority of the ~ 16 fields are updated. Also this table has numerous predefined virtual columns with fn based indexes on them.
My first inclination was to recast this using the Oracle updatexml function. I was told, the /*+ NO_XML_DML_REWRITE */ hint would also be necessary here.
update /*+ NO_XML_DML_REWRITE */
<tble_name> a
set a.object_value = updatexml(a.object_value ...).
Last year our dba's were instructed by Oracle Support to use this hint, as the update wasn't updating any records w.o any error msgs.
+1. Hoping to find out if anyone has run across using this hint in some capacity and what was their experience?+
In trying to optimizie this update statement, I'll start from scratch not using the /*+ NO_XML_DML_REWRITE */ hint and will commence with using the updatexml function with setting up an xmlindex.
+2. Hoping to receive some suggestions on creating the proper xmlindex - figuring an unstructured index. If get some good performance with the xmlindex; hoping to retire some of the virtual column usage.+
+3. Any suggestions on living with virtual columns in conjunction with xmlindexes? See the action table definition and associated ivirtual columns and indexes. This table seems over indexed...+
REATE
  TABLE "CROUTREACH"."ACTION" OF XMLTYPE
    CONSTRAINT "ACTN_ID_PK" PRIMARY KEY ("ACTN_ID") USING INDEX PCTFREE 10
    INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE(INITIAL 65536 NEXT
    1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 FREELISTS 1
    FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE
    DEFAULT) TABLESPACE "ACME_DATA" ENABLE
  XMLTYPE STORE AS SECUREFILE BINARY XML
    TABLESPACE "ACME_DATA" ENABLE STORAGE IN ROW CHUNK 8192 CACHE READS LOGGING
    NOCOMPRESS KEEP_DUPLICATES STORAGE(INITIAL 106496 NEXT 1048576 MINEXTENTS 1
    MAXEXTENTS 2147483645 PCTINCREASE 0 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
    CELL_FLASH_CACHE DEFAULT)
  ALLOW NONSCHEMA ALLOW ANYSCHEMA VIRTUAL COLUMNS
    *"ACTION_DEF_URN"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                
/action/srvContextPointer/outreachActionDefInfo/@actionDefUrn                                              
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(50))),
    *"STAT_DT"* AS (SYS_EXTRACT_UTC(CAST(TO_TIMESTAMP_TZ(SYS_XQ_UPKXML2SQL(
    SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                             
/action/@status_dt'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2),'SYYYY-MM-DD"T"HH24:MI:SS.FFTZH:TZM') AS TIMESTAMP
WITH
  TIME ZONE))),
    *"ACT_DEF_ID"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                             
/action/srvContextPointer/outreachActionDefInfo/@actionDefId'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(20))),
    *"CORRL_ID"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                             
/action/correlationId'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(50))),
    *"STAT_RSN"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                                 
/action/statusReason'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(30))),
    *"ACT_APPNT_DT"* AS (SYS_EXTRACT_UTC(CAST(TO_TIMESTAMP_TZ(SYS_XQ_UPKXML2SQL(
    SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                 
/action/actionAppointment/appointment_dt'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2),'SYYYY-MM-DD"T"HH24:MI:SS.FFTZH:TZM') AS TIMESTAMP
WITH
  TIME ZONE))),
    *"UPDT_DT"* AS (SYS_EXTRACT_UTC(CAST(TO_TIMESTAMP_TZ(SYS_XQ_UPKXML2SQL(
    SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                             
/action/@update_dt'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2),'SYYYY-MM-DD"T"HH24:MI:SS.FFTZH:TZM') AS TIMESTAMP
WITH
  TIME ZONE))),
    *"CRET_DT"* AS (SYS_EXTRACT_UTC(CAST(TO_TIMESTAMP_TZ(SYS_XQ_UPKXML2SQL(
    SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                             
/action/@create_dt'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2),'SYYYY-MM-DD"T"HH24:MI:SS.FFTZH:TZM') AS TIMESTAMP
WITH
  TIME ZONE))),
    *"ACT_SEQ"* AS (CAST(TO_NUMBER(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                   
/action/srvContextPointer/outreachActionDefInfo/@sequence'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2)) AS NUMBER(10))),
    *"SERVICE_DEF_URN"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03";                                                         
/action/srvContextPointer/serviceDefUrn'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(100))),
    *"ASSIGN_TEAM_CD"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                 
/action/assignment/@teamCategoryCode'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(50))),
    *"ASSIGN_STAFF_ID"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                 
/action/assignment/staffProfileId'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(50))),
    *"ACTION_TYPE"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03"; (::)                                                     
declare namespace xsi="http://www.w3.org/2001/XMLSchema-instance"; (::)                                                     
local-name-from-QName(QName("http://www.cigna.com/acme/domains/actions/2010/03",/action/@xsi:type))                                                                 
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(50))),
    *"ACTN_ID"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03";/action/@id'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(50))),
    *"STATUS"*AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03";/action/@status'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(20))),
    *"ACME_MBR_ID"* AS (CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(XMLQUERY(
    'declare default element namespace "http://www.cigna.com/acme/domains/actions/2010/03";/action/acmeMemberId'
    PASSING BY VALUE SYS_MAKEXML(128,"XMLDATA") RETURNING CONTENT ),0,0,
    16777216,0),50,1,2) AS VARCHAR2(50)))
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING STORAGE
    INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0
    FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
    CELL_FLASH_CACHE DEFAULT
  TABLESPACE "ACME_DATA" ;
CREATE UNIQUE INDEX *"CROUTREACH"."SYS_C0014547"* ON "CROUTREACH"."ACTION"
    "SYS_NC_OID$"
  PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
    INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0
    FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
    CELL_FLASH_CACHE DEFAULT
  TABLESPACE "ACME_DATA" ;
CREATE UNIQUE INDEX *"CROUTREACH"."SYS_IL0000082156C00003$$"* ON "CROUTREACH".
  "ACTION"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 STORAGE(INITIAL 65536 NEXT 1048576
    MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 FREELISTS 1 FREELIST
    GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
    TABLESPACE "ACME_DATA" PARALLEL (DEGREE 0 INSTANCES 0) ;
CREATE UNIQUE INDEX *"CROUTREACH"."ACTN_ID_PK"* ON "CROUTREACH"."ACTION" (
  "ACTN_ID") PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE(
  INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0
  FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
  CELL_FLASH_CACHE DEFAULT) TABLESPACE "ACME_DATA" ;
  CREATE
    INDEX *"CROUTREACH"."ACTION_STAT_RSN_IDX"* ON "CROUTREACH"."ACTION"
      "STAT_RSN"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
      INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE
      0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
      CELL_FLASH_CACHE DEFAULT
    TABLESPACE "ACME_DATA" ;
  CREATE
    INDEX *"CROUTREACH"."ACTION_UPDT_DT_IDX"* ON "CROUTREACH"."ACTION"
      "UPDT_DT"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
      INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE
      0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
      CELL_FLASH_CACHE DEFAULT
    TABLESPACE "ACME_DATA" ;
  CREATE
    INDEX *"CROUTREACH"."ACTION_CRET_DT_IDX"* ON "CROUTREACH"."ACTION"
      "CRET_DT"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
      INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE
      0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
      CELL_FLASH_CACHE DEFAULT
    TABLESPACE "ACME_DATA" ;
  CREATE
    INDEX *"CROUTREACH"."ACTION_STAT_DT_IDX"* ON "CROUTREACH"."ACTION"
      "STAT_DT"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
      INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE
      0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
      CELL_FLASH_CACHE DEFAULT
    TABLESPACE "ACME_DATA" ;
  CREATE
    INDEX *"CROUTREACH"."ACTION_MBRID_TYP_STAT_IDX"* ON "CROUTREACH"."ACTION"
      "ACME_MBR_ID",
      "ACTION_TYPE",
      "STATUS"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
      INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE
      0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
      CELL_FLASH_CACHE DEFAULT
    TABLESPACE "ACME_DATA" ;
  CREATE
    INDEX *"CROUTREACH"."ACT_ACTDEF_URN_IDX"* ON "CROUTREACH"."ACTION"
      "ACTION_DEF_URN"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
      INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE
      0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
      CELL_FLASH_CACHE DEFAULT
    TABLESPACE "ACME_DATA" ;
  CREATE
    INDEX *"CROUTREACH"."ACTION_ACT_DEF_ID_STATUS_IDX"* ON "CROUTREACH"."ACTION"
      "ACT_DEF_ID",
      "STATUS"
    PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE
      INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE
      0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT
      CELL_FLASH_CACHE DEFAULT
    TABLESPACE "ACME_DATA" ;Any suggestions much appreciated.
Regards,
Richard Blanchard

Answer 1

odie 63
update /*+ NO_XML_DML_REWRITE */croutreach.action set object_value = :1 where actn_id = :2 .
This update pattern is used in the production environment and is slowing the environment down as more xml content is increased. In a new release build, this update pattern against the action table described earlier, is particularly problematic.
Have some more information on the /*+ NO_XML_DML_REWRITE */ hint. It turns out, last year, updates statements would intermittently fail to correctly update silently failing. An Oracle Service Request was created. Over the span of about 5 mnths, Oracle determined a very low level Oracle kernel bug was the culprit. Oracle As a result of this SR, Oracle SUpport created BUG 11939507 <ORA-08102: index key not found during update on xmltable with a virtual column>. This bug is viewable on metalink. Oracle claims this bug has only been oberved on In the interim to 11.2.0.3, Oracle Support mentioned to use /*+ NO_XML_DML_REWRITE */; thus disabling piecewise update.
Here's preface information on this bug:
Bug 11939507: ORA-08102: INDEX KEY NOT FOUND DURING UPDATE ON XMLTABLE WITH VIRTUAL COLUMN  
Bug Attributes
Type B - Defect Fixed in Product Version 12.1
Severity 2 - Severe Loss of Service Product Version 11.2.0.1
Status 80 - Development to Q/A Platform 23 - Oracle Solaris on SPARC (64-bit)
Created 30-Mar-2011 Platform Version 10
Updated 13-Feb-2012 Base Bug -
Database Version 11.2.0.1  
Affects Platforms Generic  
Product Source Oracle  
Hdr: 11939507 11.2.0.1 XDB 11.2.0.1 BINARY PRODID-5 PORTID-23
Abstract: ORA-8102: INDEX KEY NOT FOUND DURING UPDATE ON XMLTABLE WITH VIRTUAL COLUMN*** 03/30/11 12:22 pm ***
BUG TYPE CHOSEN  =============== code   
Component: XML Database  ======================= 
DETAILED PROBLEM DESCRIPTION  ============================ 
The issue happens intermittently when running a batch program with 50  concurrent sessions that involves high concurrent updates.
DIAGNOSTIC ANALYSIS  ===================  reproducible testcase on customer dummy data reproduced by Thomas. 
WORKAROUND?  ===========  No   
TECHNICAL IMPACT  ================  Customer is experiencing this error which is critical to the application  because it causes a home health care provider to possibly lose a couple  hours worth of work and have to start from scratch. The condition has only  accessed concurrently from about 40 threads  
RELATED ISSUES (bugs, forums, RFAs)  ===================================  Bug 8514561 - ORA-8102 WHEN UPDATING TABLE
HOW OFTEN DOES THE ISSUE REPRODUCE AT CUSTOMER SITE?  ====================================================  Intermittent  
DOES THE ISSUE REPRODUCE INTERNALLY?  ====================================  Intermittent
IS A TESTCASE AVAILABLE?  ========================  Yes  The good news is, this bug is corrupting a virtual index column.
I'll try test cases using the update pattern; 'update /*+ NO_XML_DML_REWRITE */croutreach.action set object_value = :1 where actn_id = :2 ' - substituting actual values for the bind variables and removing interfering virtual columns. Wil lcompare with and w/o the hint.
This wil address your; "Where does the new values come from? Individual variables?" - and provide sample data.
Presently, this update pattern is used 'blindly' in that when no xml relevent changes are identified, only a couple of the roughly 16 fields are updated - yet the whole document gets updated with this update pattern. When changes occur, the whole document is updated. Will work with updating 1 or 2 fields using updatexml and try the xmlexists function for the predicate.
04/25/12 Update:
odie 63,
Here's a sample xml record from the action securefile binary xml table:
<?xml version = '1.0' encoding = 'UTF-8' standalone = 'yes'?><action xsi:type="AssessmentActionType" status_dt="2012-01-18T19:38:21.077Z" status="not applicable" create_dt="2012-01-17T23:10:16.173Z" id="dfdfdfdfdfddfdfdfdfdfdf" xmlns:ns5="http://www.xxxxx.ddd/exception/definition/schema/2010/01" xmlns="http://www.xxxxxx.ddd/mmm/domains/actions/2010/03" xmlns:ns6="http://www.xxxxx.ddd/mmm/domains/utility/outcome/2010/03" xmlns:ns7="http://www.xxxxxx.ddd/mmm/domains/common/2010/03" xmlns:ns2="http://www.xxxxx.ddd/mmm/messages/actions/2010/03" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns3="http://www.xxxxx.ddd/mmm/domains/workforce/2010/03" xmlns:ns4="http://www.xxxxxx.ddd/mmm/domains/entitlement/2011/11">
   <acmeMemberId>abcdefghijklmnop</acmeMemberId>
   <advocacyPlanId>qrstuvwxyz</advocacyPlanId>
   <srvContextPointer>
      <serviceDefUrn>urn:coderunner:Medical:Definition:ServiceService:11111:7</serviceDefUrn>
      <outreachActionDefInfo sequence="1" actionDefUrn="urn:xxxxxxxxxx:Medical:Definition:Action:50813:2" actionDefId="xxxxxx">
         <srvContextPath>Access Profile~Why did you access the profile?~Reason for access?</srvContextPath>
      </outreachActionDefInfo>
   </srvContextPointer>
</action>Started out using this update statement against the virtual column a.actn_id. This column is also indexed as a fbi.
UPDATE /*+ NO_XML_DML_REWRITE */ action A
SET A.object_value = updatexml(A.object_value,'/action/@status','triggered','xmlns="http://www.xxxx.vvv/yyy/domains/actions/2010/03"')
where a.actn_id='888a80be-d69f-464d-b3f7-85b6209f918e';
This statment updates fine with and w/o the hint. This hint takes away the piecewise update of the xml document and relies upon the a.actn_id virtual column.
Then removed the reliance on the virtual column using the xmlexists fn.
First did an alter index 'actn_id_pk invisible' to take the virtual column out of consideration by the optimizer.
UPDATE /*+ NO_XML_DML_REWRITE */ action A
SET A.object_value = updatexml(A.object_value,'/action/@status','triggered','xmlns="http://www.xxxx.vvv/yyy/domains/actions/2010/03"')
where xmlexists('$p/action[@id="'888a80be-d69f-464d-b3f7-85b6209f918e'"]' PASSING object_value as "p");
This update runs but doesn't update any columns - with or without the hint.
Also created a basic unstructured xmlindex to remove the full table scan - which worked fine execution plan-wise.
create index action_xmlindex_ix on action (object_value) indextype is xdb.xmlindex;Per the SR on this, the /*+ NO_XML_DML_REWRITE */ disables piecewise update and is a workaround for the bug surrounding virtual column index usage when having many concurrent sessions and updates against a table with millions of xml documents. Getting rid of the virtual column in the predicate removes the need for the workaround hint.
My problem is This update runs but doesn't update any columns. Maybe am missing something or doing a syntax/semantic error ?
Any assistance much appreciated...
Regards,
Rick Blanchard
Edited by: RickBlanchardSRSCigna on Apr 25, 2012 12:52 PM