Something new? Eh? Should you do this? Eh?
In all, probably not, but for me this was a good exercise towards some more updated demo scripting for my “Boost your environment with XMLDB” presentation or hopefully more clearer relabeled Oracle Open World name for the almost same presentation called “Interfacing with Your Database via Oracle XML DB” (S319105). Just up front, there are some issues with the following:
- Why should you do it at all. You should have a good reason doing so…
- It can cause a lot of Physical I/O, at least initially when not cached in the SGA
- Until current versions, AFAIK, it will do a lot of “Pickler Fetching”, serializing in memory, which is very resource intensive (CPU/PGA)
- …and its probably not supported…?
…but it is good fun for a small exercise based on the following OTN Thread: “Error with basic XMLTable“…
Let me show you what I mean.
Via “bfilename” you are able, since a long time, I guess Oracle 9.2 and onwards, to read a file as a BLOB and because an “XMLTYPE” can swallow almost any datatype, you could do the following…
[oracle@localhost ~]$ sqlplus / AS sysdba SQL*Plus: Release 11.2.0.1.0 Production ON Thu Jul 29 09:20:24 2010 Copyright (c) 1982, 2009, Oracle. ALL rights reserved. Connected TO: Oracle DATABASE 11g Enterprise Edition Release 11.2.0.1.0 - Production WITH the Partitioning, OLAP, DATA Mining AND Real Application Testing options SQL> CREATE user otn IDENTIFIED BY otn account UNLOCK; User created. SQL> GRANT dba TO otn; GRANT succeeded. SQL> conn otn/otn Connected. SQL> sho user USER IS "OTN" SQL> SET pages 5000 SQL> SET LINES 1000 SQL> SET long 10000 SQL> SELECT xmltype(cursor(SELECT owner, schema_url, LOCAL FROM all_xml_schemas ORDER BY owner)) FROM dual; XMLTYPE(CURSOR(SELECTOWNER,SCHEMA_URL,LOCALFROMALL_XML_SCHEMASORDERBYOWNER)) ----------------------------------------------------------------------------------------------------------- < ?xml version="1.0"?> <rowset> <row> <owner>EXFSYS</owner> <schema_url>http://xmlns.oracle.com/rlmgr/rclsprop.xsd</schema_url> <local>NO</local> </row> <row> <owner>EXFSYS</owner> <schema_url>http://xmlns.oracle.com/rlmgr/rulecond.xsd</schema_url> <local>NO</local> </row> <row> <owner>MDSYS</owner> <schema_url>http://www.opengis.net/gml/feature.xsd</schema_url> <local>NO</local> </row> <row> ... </row><row> <owner>XDB</owner> <schema_url>http://xmlns.oracle.com/xdb/dav.xsd</schema_url> <local>NO</local> </row> </rowset> 51 rows selected.
Lets write the output to disk in the /tmp directory or my Oracle Enterprise Linux environment…
SQL> sho user USER IS "OTN" SQL> CREATE OR REPLACE directory XMLDIR AS '/tmp/'; Directory created. SQL> declare 2 rc sys_refcursor; 3 begin 4 open rc FOR SELECT * FROM (SELECT owner, schema_url, LOCAL FROM all_xml_schemas ORDER BY owner); 5 dbms_xslprocessor.clob2file(xmltype(rc).getClobVal(),'TMPDIR','otn_dev_xsd_schema.xml'); 6 end; 7 ; PL/SQL procedure successfully completed. SQL> commit; commit complete SQL> ! ls -ltra /tmp/*.xml -rw-rw-r-- 1 oracle oracle 6563 Jul 29 09:36 /tmp/otn_dev_xsd_schema.xml
Due to the fact the content of this XML file (be aware: 6K) is wellformed XML, for example the alert log is not wellformed, and I know its format, I could read it directly from my database session via the following…
SQL> SELECT xmltype(bfilename('TMPDIR','otn_dev_xsd_schema.xml'), nls_charset_id('AL32UTF8')) FROM dual; XMLTYPE(BFILENAME('TMPDIR','OTN_DEV_XSD_SCHEMA.XML'),NLS_CHARSET_ID('AL32UTF8')) --------------------------------------------------------------------------------------- < ?xml version="1.0"?> <rowset> <row> <owner>EXFSYS</owner> <schema_url>http://xmlns.oracle.com/rlmgr/rclsprop.xsd</schema_url> <local>NO</local> </row> <row> <owner>EXFSYS</owner> <schema_url>http://xmlns.oracle.com/rlmgr/rulecond.xsd</schema_url> <local>NO</local> </row> <row> <owner>MDSYS</owner> <schema_url>http://www.opengis.net/gml/feature.xsd</schema_url> <local>NO</local> </row> <row> <owner>MDSYS</owner> <schema_url>http://xmlns.oracle.com/spatial/georaster/georaster.xsd</schema_url> <local>NO</local> </row> <row> <owner>MDSYS</owner> <schema_url>http://www.w3.org/1999/xlink/xlinks.xsd</schema_url> <local>NO</local> </row> <row> <owner>MDSYS</owner> <schema_url>http://www.opengis.net/gml/geometry.xsd</schema_url> <local>NO</local> </row> Â ... Â <row> Â Â <owner>XDB</owner> <schema_url>http://xmlns.oracle.com/xdb/dav.xsd</schema_url> <local>NO</local> </row> </rowset> 51 rows selected.
That easy, although as said it has some issues, performance wise. From Oracle database version 10.2.0.1 and onwards, although I would use as a minimum 10.2.0.3.0 due to that the XQuery engine is C, Oracle kernel build-in based, you could now use the XMLTABLE function, to handle it further. XMLTABLE is a great function to make convert XML in a more relational in look-and-feel and / or because it supports XQuery version 1.0 (and as you (should) know XQuery is a very powerful query language). Anyway, via XMLTABLE, we can now show data in a relational form is demonstrated via the following:
SQL> SELECT xtab.owner 2 , xtab.schema_url 3 , xtab.LOCAL 4 FROM (SELECT xmltype(bfilename('TMPDIR','otn_dev_xsd_schema.xml'), nls_charset_id('AL32UTF8')) OBJECT_VALUE FROM dual) xfile 5 , XMLTABLE ('/ROWSET/ROW' 6 PASSING xfile.object_value 7 COLUMNS OWNER VARCHAR2(30) path 'OWNER' 8 , SCHEMA_URL VARCHAR2(80) path 'SCHEMA_URL' 9 , LOCAL VARCHAR2(3) path 'LOCAL' 10 ) xtab 11 ; OWNER SCHEMA_URL LOC ------------------------------ -------------------------------------------------------------------------------- --- EXFSYS http://xmlns.oracle.com/rlmgr/rclsprop.xsd NO EXFSYS http://xmlns.oracle.com/rlmgr/rulecond.xsd NO MDSYS http://www.opengis.net/gml/feature.xsd NO MDSYS http://xmlns.oracle.com/spatial/georaster/georaster.xsd NO MDSYS http://www.w3.org/1999/xlink/xlinks.xsd NO MDSYS http://www.opengis.net/gml/geometry.xsd NO ORDSYS http://xmlns.oracle.com/ord/dicom/preference_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/mapping_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/metadata_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/constraint_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/anonymity_1_0 NO ORDSYS http://xmlns.oracle.com/ord/meta/xmp NO ORDSYS http://xmlns.oracle.com/ord/dicom/standardDictionary_1_0 NO ORDSYS http://xmlns.oracle.com/ord/meta/iptc NO ORDSYS http://xmlns.oracle.com/ord/dicom/mddatatype_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/orddicom_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/datatype_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/privateDictionary_1_0 NO ORDSYS http://xmlns.oracle.com/ord/meta/exif NO ORDSYS http://xmlns.oracle.com/ord/dicom/rpdatatype_1_0 NO ORDSYS http://xmlns.oracle.com/ord/meta/ordimage NO ORDSYS http://xmlns.oracle.com/ord/dicom/UIDdefinition_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/manifest_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/attributeTag_1_0 NO ... XDB http://xmlns.oracle.com/xdb/XDBStandard.xsd NO XDB http://xmlns.oracle.com/xdb/XDBResConfig.xsd NO XDB http://xmlns.oracle.com/xdb/acl.xsd NO XDB http://xmlns.oracle.com/xdb/dav.xsd NO 51 rows selected.
…and due to the fact you can query it, you can create a view out of it…
SQL> CREATE or REPLACE view MY_EXTERNAL_XFILE 2 ( OWNER 3 , SCHEMA 4 , MINE 5 ) 6 AS 7 SELECT xtab.owner 8 , xtab.schema_url 9 , xtab.local 10 FROM (select xmltype(bfilename('TMPDIR','otn_dev_xsd_schema.xml'), nls_charset_id('AL32UTF8')) OBJECT_VALUE from dual) xfile 11 , XMLTABLE ('/ROWSET/ROW' 12 PASSING xfile.object_value 13 COLUMNS OWNER VARCHAR2(30) path 'OWNER' 14 , SCHEMA_URL VARCHAR2(80) path 'SCHEMA_URL' 15 , LOCAL VARCHAR2(3) path 'LOCAL' 16 ) xtab 17 ; View created. SQL> desc my_external_xfile Name Null? Type ----------------------------------------- -------- ---------------------------- OWNER VARCHAR2(30) SCHEMA VARCHAR2(80) MINE VARCHAR2(3) SQL> select * from MY_EXTERNAL_XFILE 2 ; OWNER SCHEMA MIN ------------------------------ -------------------------------------------------------------------------------- --- EXFSYS http://xmlns.oracle.com/rlmgr/rclsprop.xsd NO EXFSYS http://xmlns.oracle.com/rlmgr/rulecond.xsd NO MDSYS http://www.opengis.net/gml/feature.xsd NO MDSYS http://xmlns.oracle.com/spatial/georaster/georaster.xsd NO MDSYS http://www.w3.org/1999/xlink/xlinks.xsd NO MDSYS http://www.opengis.net/gml/geometry.xsd NO ORDSYS http://xmlns.oracle.com/ord/dicom/preference_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/mapping_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/metadata_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/constraint_1_0 NO ORDSYS http://xmlns.oracle.com/ord/dicom/anonymity_1_0 NO ... XDB http://xmlns.oracle.com/xdb/XDBStandard.xsd NO XDB http://xmlns.oracle.com/xdb/XDBResConfig.xsd NO XDB http://xmlns.oracle.com/xdb/acl.xsd NO XDB http://xmlns.oracle.com/xdb/dav.xsd NO 51 rows selected.
So now we have a “standard” relational view that we can query, for example, show me all “w3” based in the XDB Repository registered XML Schemas which are not mine, but accessible for all in the database, via…
SQL> select * from MY_EXTERNAL_XFILE where owner='XDB' 2 and instr(SCHEMA,'w3') > 0 3 ; OWNER SCHEMA MIN ------------------------------ -------------------------------------------------------------------------------- --- XDB http://www.w3.org/2001/csx.xml.xsd NO XDB http://www.w3.org/2001/csx.XInclude.xsd NO XDB http://www.w3.org/2001/XInclude.xsd NO XDB http://www.w3.org/1999/csx.xlink.xsd NO XDB http://www.w3.org/1999/xlink.xsd NO XDB http://www.w3.org/2001/xml.xsd NO 6 rows selected.
Price to pay…?
As said, it comes with a price to pay, regarding I/O and other performance issues. For example check out the following stats, initially via “explain plan”…
SQL> conn / as sysdba Connected. SQL> startup ORACLE instance started. Total System Global Area 313860096 bytes Fixed Size 1336232 bytes Variable Size 251661400 bytes Database Buffers 54525952 bytes Redo Buffers 6336512 bytes Database mounted. Database opened. SQL> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production PL/SQL Release 11.2.0.1.0 - Production CORE 11.2.0.1.0 Production TNS for Linux: Version 11.2.0.1.0 - Production NLSRTL Version 11.2.0.1.0 - Production SQL> set autotrace on SQL> select * from MY_EXTERNAL_XFILE where owner='MDSYS' 2 and instr(SCHEMA,'w3') > 0; OWNER SCHEMA MIN ------------------------------ -------------------------------------------------------------------------------- --- MDSYS http://www.w3.org/1999/xlink/xlinks.xsd NO Execution Plan ---------------------------------------------------------- Plan hash value: 2888251253 ------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 4 | 8 | 44 (30)| 00:00:01 | | 1 | NESTED LOOPS | | 4 | 8 | 44 (30)| 00:00:01 | | 2 | FAST DUAL | | 1 | | 2 (0)| 00:00:01 | |* 3 | COLLECTION ITERATOR PICKLER FETCH| XMLSEQUENCEFROMXMLTYPE | 4 | 8 | 42 (31)| 00:00:01 | ------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/OWNER'),0,0,209715 20,0),50,1,2) AS VARCHAR2(30) )='MDSYS' AND INSTR(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VA LUE(KOKBF$),'/ROW/SCHEMA_URL'),0,0,20971520,0),50,1,2) AS VARCHAR2(80) ),'w3')>0) Statistics ---------------------------------------------------------- 3624 recursive calls 0 db block gets 2888 consistent gets 105 physical reads 0 redo size 583 bytes sent via SQL*Net to client 419 bytes received via SQL*Net from client 2 SQL*Net roundtrips to/from client 143 sorts (memory) 0 sorts (disk) 1 rows processed SQL> select * from MY_EXTERNAL_XFILE where owner='MDSYS' 2 and instr(SCHEMA,'w3') > 0; OWNER SCHEMA MIN ------------------------------ -------------------------------------------------------------------------------- --- MDSYS http://www.w3.org/1999/xlink/xlinks.xsd NO Execution Plan ---------------------------------------------------------- Plan hash value: 2888251253 ------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 4 | 8 | 44 (30)| 00:00:01 | | 1 | NESTED LOOPS | | 4 | 8 | 44 (30)| 00:00:01 | | 2 | FAST DUAL | | 1 | | 2 (0)| 00:00:01 | |* 3 | COLLECTION ITERATOR PICKLER FETCH| XMLSEQUENCEFROMXMLTYPE | 4 | 8 | 42 (31)| 00:00:01 | ------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/OWNER'),0,0,209715 20,0),50,1,2) AS VARCHAR2(30) )='MDSYS' AND INSTR(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VA LUE(KOKBF$),'/ROW/SCHEMA_URL'),0,0,20971520,0),50,1,2) AS VARCHAR2(80) ),'w3')>0) Statistics ---------------------------------------------------------- 0 recursive calls 0 db block gets 3 consistent gets 0 physical reads 0 redo size 583 bytes sent via SQL*Net to client 419 bytes received via SQL*Net from client 2 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 1 rows processed
…and a second time via the same “procedure” checking via the stats via DBMS_XPLAN…
SQL> startup force ORACLE instance started. Total System Global Area 313860096 bytes Fixed Size 1336232 bytes Variable Size 251661400 bytes Database Buffers 54525952 bytes Redo Buffers 6336512 bytes Database mounted. Database opened. SQL> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production PL/SQL Release 11.2.0.1.0 - Production CORE 11.2.0.1.0 Production TNS for Linux: Version 11.2.0.1.0 - Production NLSRTL Version 11.2.0.1.0 - Production SQL> conn otn/otn Connected. SQL> alter session set statistics_level=all; Session altered. SQL> create or replace view xplan as select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST')); View created. SQL> select * from MY_EXTERNAL_XFILE where owner='MDSYS' 2 and instr(SCHEMA,'w3') > 0; SQL> select * from MY_EXTERNAL_XFILE where owner='MDSYS' 2 and instr(SCHEMA,'w3') > 0; OWNER SCHEMA MIN ------------------------------ -------------------------------------------------------------------------------- --- MDSYS http://www.w3.org/1999/xlink/xlinks.xsd NO SQL> select * from xplan; PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------------------------------------------------------- SQL_ID 9kc32mbtas765, child number 0 ------------------------------------- select * from MY_EXTERNAL_XFILE where owner='MDSYS' and instr(SCHEMA,'w3') > 0 Plan hash value: 2888251253 -------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | -------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.09 | 959 | 52 | | 1 | NESTED LOOPS | | 1 | 4 | 1 |00:00:00.09 | 959 | 52 | | 2 | FAST DUAL | | 1 | 1 | 1 |00:00:00.01 | 0 | 0 | |* 3 | COLLECTION ITERATOR PICKLER FETCH| XMLSEQUENCEFROMXMLTYPE | 1 | 4 | 1 |00:00:00.08 | 959 | 52 | -------------------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter((CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/OWNER'),0,0,20971520,0),50,1,2) AS VARCHAR2(30) )='MDSYS' AND INSTR(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/SCHEMA_URL'),0,0,2 0971520,0),50,1,2) AS VARCHAR2(80) ),'w3')>0)) 23 rows selected. SQL> select * from MY_EXTERNAL_XFILE where owner='MDSYS' 2 and instr(SCHEMA,'w3') > 0; OWNER SCHEMA MIN ------------------------------ -------------------------------------------------------------------------------- --- MDSYS http://www.w3.org/1999/xlink/xlinks.xsd NO SQL> select * from xplan; PLAN_TABLE_OUTPUT ----------------------------------------------------------------------------------------------------------------------- SQL_ID 9kc32mbtas765, child number 0 ------------------------------------- select * from MY_EXTERNAL_XFILE where owner='MDSYS' and instr(SCHEMA,'w3') > 0 Plan hash value: 2888251253 ----------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | ----------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.01 | 3 | | 1 | NESTED LOOPS | | 1 | 4 | 1 |00:00:00.01 | 3 | | 2 | FAST DUAL | | 1 | 1 | 1 |00:00:00.01 | 0 | |* 3 | COLLECTION ITERATOR PICKLER FETCH| XMLSEQUENCEFROMXMLTYPE | 1 | 4 | 1 |00:00:00.01 | 3 | ----------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter((CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/OWNER'),0,0,20971520,0),50, 1,2) AS VARCHAR2(30) )='MDSYS' AND INSTR(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/S CHEMA_URL'),0,0,20971520,0),50,1,2) AS VARCHAR2(80) ),'w3')>0)) 23 rows selected.
As said before, initially Oracle has to do a lot of disk reads and all has to be done via “COLLECTION ITERATOR PICKLER FETCH”, which means in memory, but although in memory, Oracle is able to rewrite it via the XQuery engine (mark the “XQ” in the filter statements) to their relational counter parts due to the fact that Oracle got this information via the XMLTABLE function definition.
The second time around everything has been cached. See the following output via all statistics / DBMS_XPLAN…
SQL> select * from MY_EXTERNAL_XFILE where owner='XDB' 2 and instr(SCHEMA,'w3') = 0 3 ; OWNER SCHEMA MIN ------------------------------ -------------------------------------------------------------------------------- --- XDB http://xmlns.oracle.com/xdb/csx.xmltr.xsd NO XDB http://xmlns.oracle.com/xdb/XDBResource.xsd NO XDB http://xmlns.oracle.com/xdb/XDBSchema.xsd NO XDB http://xmlns.oracle.com/xs/principal.xsd NO XDB http://xmlns.oracle.com/xs/aclids.xsd NO XDB http://xmlns.oracle.com/xs/dataSecurity.xsd NO XDB http://xmlns.oracle.com/xdb/xdbconfig.xsd NO XDB http://xmlns.oracle.com/xs/securityclass.xsd NO XDB http://xmlns.oracle.com/xs/roleset.xsd NO XDB http://xmlns.oracle.com/xdb/stats.xsd NO XDB http://xmlns.oracle.com/xdb/XDBFolderListing.xsd NO XDB http://xmlns.oracle.com/xdb/xmltr.xsd NO XDB http://xmlns.oracle.com/xdb/log/httplog.xsd NO XDB http://xmlns.oracle.com/xdb/log/ftplog.xsd NO XDB http://xmlns.oracle.com/xdb/log/xdblog.xsd NO XDB http://xmlns.oracle.com/xdb/XDBStandard.xsd NO XDB http://xmlns.oracle.com/xdb/XDBResConfig.xsd NO XDB http://xmlns.oracle.com/xdb/acl.xsd NO XDB http://xmlns.oracle.com/xdb/dav.xsd NO 19 rows selected. SQL> select * from xplan; PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- SQL_ID bjx9wfv2hp6u7, child number 0 ------------------------------------- select * from MY_EXTERNAL_XFILE where owner='XDB' and instr(SCHEMA,'w3') = 0 Plan hash value: 2888251253 ----------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | ----------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 19 |00:00:00.03 | 3 | | 1 | NESTED LOOPS | | 1 | 1 | 19 |00:00:00.03 | 3 | | 2 | FAST DUAL | | 1 | 1 | 1 |00:00:00.01 | 0 | |* 3 | COLLECTION ITERATOR PICKLER FETCH| XMLSEQUENCEFROMXMLTYPE | 1 | 1 | 19 |00:00:00.03 | 3 | ----------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter((CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/OWNER'),0,0,20971520,0),50, 1,2) AS VARCHAR2(30) )='XDB' AND INSTR(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/SCH EMA_URL'),0,0,20971520,0),50,1,2) AS VARCHAR2(80) ),'w3')=0)) 23 rows selected. SQL> select owner, count(*) 2 from MY_EXTERNAL_XFILE 3 where instr(SCHEMA,'xmlns.oracle.com') > 0 4 group by owner; OWNER COUNT(*) ------------------------------ ---------- MDSYS 1 EXFSYS 2 ORDSYS 19 XDB 19 SYS 1 SQL> select * from xplan; PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- SQL_ID 5sqvj1k6pmmxj, child number 0 ------------------------------------- select owner, count(*) from MY_EXTERNAL_XFILE where instr(SCHEMA,'xmlns.oracle.com') > 0 group by owner Plan hash value: 2770558904 --------------------------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem | --------------------------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 5 |00:00:00.03 | 3 | | | | | 1 | HASH GROUP BY | | 1 | 408 | 5 |00:00:00.03 | 3 | 855K| 855K| 917K (0)| | 2 | NESTED LOOPS | | 1 | 408 | 42 |00:00:00.02 | 3 | | | | | 3 | FAST DUAL | | 1 | 1 | 1 |00:00:00.01 | 0 | | | | |* 4 | COLLECTION ITERATOR PICKLER FETCH| XMLSEQUENCEFROMXMLTYPE | 1 | 408 | 42 |00:00:00.02 | 3 | | | | --------------------------------------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 4 - filter(INSTR(CAST(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(VALUE(KOKBF$),'/ROW/SCHEMA_URL'),0,0,20971520,0),50,1,2) AS VARCHAR2(80) ),'xmlns.oracle.com')>0) 23 rows selected.
Who knows with a little bit of fantasy, me or you, could find a case this could be applied and makes sense. This example was based on the following OTN Thread: “Error with basic XMLTable” and its probably easier to read up it over there. Hope you liked it.