Where clause with XMLExists and join on another table

Question

Hi,
We have table like:
drop table xml_tbl;
create table xml_tbl (
xml_msg_id integer,
xml_msg_text xmltype
insert into xml_tbl values
(1, '<main><id>1</id></main>') ;
insert into xml_tbl values --(xml_msg_id,xml_msg_text)
(1, '<main><id>2</id></main>') ;
Another table like:
create Table Table1
( id1 int);
Insert into Table1 values(2);
Insert into Table1 values(3);
We need to have a view on top of the table xml_tbl where /main/id should have only those values which are in id1 column of table Table1.
Something like
CREATE OR REPLACE VIEW V_xml_tbl
xml_msg_text
AS
SELECT T.xml_msg_text
FROM xml_tbl T
WHERE XMLEXISTS (
'declare namespace Namesp1 ="Abc:Set";
let $Results as xs:boolean := fn:exists($p/main/id in (Select id1 from Table1)) --Now here I know I can't do Select id1 from
Table1*
return if ($Results ) then true() else ()'
PASSING T.xml_msg_text AS "p");
Actually in the real scenario Table1 will have many IDs and xml_tbl has many XML files..
So I am stuck on how to do it. Please help.
Thanks..
Edited by: user8941550 on Nov 20, 2012 7:19 PM

Answer 1

One of these two :
SQL> select t.xml_msg_text
  2  from xml_tbl t
  3  where exists (
  4    select null
  5    from table1 t1
  6    where t1.id1 = xmlcast(
  7                     xmlquery('/main/id' passing t.xml_msg_text returning content)
  8                     as integer
  9                   )
10  );
XML_MSG_TEXT
<main>
  <id>2</id>
</main>
SQL> select t.xml_msg_text
  2  from xml_tbl t
  3     , xmltable('/main' passing t.xml_msg_text
  4         columns id integer path 'id'
  5       ) x
  6  where exists (
  7    select null
  8    from table1 t1
  9    where t1.id1 = x.id
10  );
XML_MSG_TEXT
<main>
  <id>2</id>
</main>
And a third one, using XMLExists :
SQL> select t.xml_msg_text
  2  from xml_tbl t
  3  where xmlexists (
  4    'fn:collection("oradb:/DEV/TABLE1")/ROW[ID1=$d/main/id]'
  5    passing t.xml_msg_text as "d"
  6  );
XML_MSG_TEXT
<main>
  <id>2</id>
</main>
Execution Plan
Plan hash value: 3633580934
| Id  | Operation           | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT    |         |     2 |   116 |     8   (0)| 00:00:01 |
|*  1 |  FILTER             |         |       |       |            |          |
|   2 |   TABLE ACCESS FULL | XML_TBL |     2 |   116 |     3   (0)| 00:00:01 |
|   3 |   NESTED LOOPS      |         |     1 |     5 |     5   (0)| 00:00:01 |
|   4 |    TABLE ACCESS FULL| TABLE1  |     2 |     6 |     3   (0)| 00:00:01 |
|*  5 |    XPATH EVALUATION |         |       |       |            |          |
Predicate Information (identified by operation id):
   1 - filter( EXISTS (SELECT 0 FROM "DEV"."TABLE1"
              "SYS_ORAVW_2",XPATHTABLE('/main/id' PASSING :B1 COLUMNS "C_00$" XMLTYPE
              PATH '.', "C_01$" XQEXVAL CHAR PATH '.')  "P" WHERE
              TO_BINARY_DOUBLE("ID1")=TO_BINARY_DOUBLE("P"."C_01$")))
   5 - filter(TO_BINARY_DOUBLE("ID1")=TO_BINARY_DOUBLE("P"."C_01$"))The plan is similar to that of the second query above (XMLTable/EXISTS).
Still using XMLExists, a plan similar to the first query (EXISTS/XMLCast/XMLQuery) can be achieved by casting id to an integer datatype :
SQL> select t.xml_msg_text
  2  from xml_tbl t
  3  where xmlexists (
  4    'fn:collection("oradb:/DEV/TABLE1")/ROW[ID1=xs:int($d/main/id)]'
  5    passing t.xml_msg_text as "d"
  6  );
XML_MSG_TEXT
<main>
  <id>2</id>
</main>
Execution Plan
Plan hash value: 1149640166
| Id  | Operation          | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |         |     1 |    61 |     7  (15)| 00:00:01 |
|*  1 |  HASH JOIN SEMI    |         |     1 |    61 |     7  (15)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| XML_TBL |     2 |   116 |     3   (0)| 00:00:01 |
|   3 |   TABLE ACCESS FULL| TABLE1  |     2 |     6 |     3   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - access("ID1"=SYS_XQ_ATOMCNVCHK(TO_NUMBER(SYS_XQ_UPKXML2SQL(SYS_XQ
              EXVAL(SYS_XQEXTRACT(SYS_MAKEXML(0,"T"."SYS_NC00003$"),'/main/id'),1,50,3
              3792,8192),50,1,0)),2,37))
Note
   - Unoptimized XML construct detected (enable XMLOptimizationCheck for more information)Check each one on your real scenario to see which show best performance.
(I would tend to say the ones involving streaming evaluation)
Edited by: odie_63 on 5 nov. 2012 12:24
Edited by: odie_63 on 5 nov. 2012 12:38