A query on bind variables

Hello

I have a procedure that takes the deptno parameter and inserts that records departments of the table emp for the new table.

This code does not exist in a real system. I was trying to understand that the advantage of linking variable.i he wrote in different ways as below

Create table emp3 as select * from emp where 1=2;

create or replace procedure test1 (p_deptno in number)as 
begin
 execute immediate 'insert into emp3
                               select *
                               from emp
                               where deptno=:1'
                               using p_deptno;
end;

The works fine.i code above writes the following much too.

create or replace procedure test2 (p_deptno in number)as 
begin
 insert into emp3
      select *
      from emp
      where deptno=p_deptno;
end;

the first no matter what performance benefit over the second one that is the right way to do it in a real-world system?
. I could not do a comparison of performance because I don't have access to a currently oracle instance and did it in workshop SQL that comes with Apex.My apology for this...

Kind regards
CKLP

Published by: CKLP on August 29, 2011 03:21

CKLP wrote:

the first no matter what performance benefit over the second one that is the right way to do it in a real-world system?

Not really. Do not forget that all interpreted SQLs winds up as sliders to the sharing of the database Pool.

If a cursor exists already for a SQL statement, SQL will reuse this slider existing (soft parser). So in a SQL engine perspective, there is no different between the two methods. These statements will be btw generate the same cursor SQL - code SQL of base and bind variable positions are identical.

From a PL/SQL's point of view, there is a huge difference.

The first option may be a little slower. Why? There he uses the immediate execution interface which is not as optimized as the implicit cursor to the PL/SQL interface. You use a "heavier" SQL interface in PL/SQL which results in more work for the PL/SQL engine.

The second option is compiled in an implicit cursor. The SQL code is known, controlled and checked, and compiled PL/SQL code deals with a known SQL statement. Unlike the first option.

The second option also means that your code will not fail (because SQL syntax errors, etc.) currently running. If this static SQL statement in your code is no longer valid (due to a table being deleted, used column removed, etc.), then your code becomes invalid. With the first option, the code remains valid - and when it is executed, it will throw an exception that the (dynamic) SQL cannot be analyzed and that it is not valid.

The first option also introduces the spectrum of a SQL injection. Let's say that there is a way to cause a buffer overflow exploit in the database call that executes this procedure. The SQL itself is a string, it is an easy attack vector as the overflow needs that data of type string to inject executable code - as opposed to the p-code or machine code. (an unlikely scenario, but the basic principle of security remains true)

Dynamic SQL is unnecessary for 99% of the time in PL/SQL. And 99% of the time, with the help of the dynamic SQL is for the wrong reasons, or ignorance or both.

Tags: Database

Similar Questions

Create the collection of query with bind variable

Apex 4.0.2

By Joel Re: Collection with variable binding the apex_collection.create_collection_from_query_b supports queries containing references to the bind variables (: P1_X) but I don't know how to use this feature, the documentation is not an example, just the API signature for the overloaded version has changed.

If the query contains 2 bind session state variable references (: P1_X and: P1_Y), can someone please show an example of what to spend for the parameters p_names and p_values to the API?

Thank you

procedure create_collection_from_query_b(
    --
    -- Create a named collection from the supplied query using bulk operations.  The query will
    -- be parsed as the application owner.  If a collection exists with the same name for the current
    -- user in the same session for the current Flow ID, an application error will be raised.
    --
    -- This procedure uses bulk dynamic SQL to perform the fetch and insert operations into the named
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    --   1) The MD5 checksum for the member data will not be computed
    --   2) No column value in query p_query can exceed 2,000 bytes
    --
    --
    -- Arguments:
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    --                            255 bytes.  Note that collection_names are case-insensitive,
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    p_collection_name in varchar2,
    p_query           in varchar2,
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    p_max_row_count   in number default null)
    ;

HELEN wrote:
Apex 4.0.2

By Joel Re: Collection with variable binding the apex_collection.create_collection_from_query_b supports queries containing references to the bind variables (: P1_X) but I don't know how to use this feature, the documentation is not an example, just the API signature for the overloaded version has changed.

If the query contains 2 bind session state variable references (: P1_X and: P1_Y), can someone please show an example of what to spend for the parameters p_names and p_values to the API?

Not tried, but guess something like

apex_collection.create_collection_from_query_b(
    p_collection_name => 'foobar'
  , p_query => 'select f.foo_id, b.bar_id, b.baz from foo f, bar b where f.foo_id = b.foo_id and f.x = to_number(:p1_x) and b.y = :p1_y'
  , p_names => apex_util.string_to_table('p1_x:p1_y')
  , p_values => apex_util.string_to_table(v('p1_x') || ':' || v('p1_y')))

How to find the query select bind variables
How to extract the variable name to bind to AS suite of sql queries
' SELECT NAME IN: NAME OF THE DOUBLE '
or
"SELECT * FROM WHERE DOUBLE (: NAME = NAME)".
or
"SELECT * FROM WHERE DOUBLE: NAME IS NULL'."
or
"SELECT * FROM WHERE DOUBLE: NAME | NAME = LAST_NAME'
or
' SELECT * FROM DUAL WHERE: a = 10'
or
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or
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Give a solution using SUBSTR, REGEXP_SUBSTR, please answer quickly
best answer will be marked correct/good...
Search: and then search for the following word breaker then have the substr for them: and the separator.
You can build an own function to find the same.

query about bind variable
Can I change the value of a variable binding within a pl/sql block. I tried something like

variable number of mybind;
run: mybind: = 20;

declare
run: mybind: =: mybind + 1;
my_variable number: = 4 *: mybind;

Start

dbms_output.put_line ($my_var);
end;

But it does not work. Help, please.
Thanks in advance

Published by: user11930797 on April 22, 2010 03:02
Define a local pl/sql variable in your statement and assign the SQL more variable to the local variable. The local variable can act as a variable binding to any SQL that you run later in your pl/sql block.
```
variable mybind number;
execute :mybind := 20;

declare
  l_mybind number := :mybind+1;
  my_var number := 4*l_mybind;

begin

  -- Here you can modify the local varaible
  dbms_output.put_line(my_var);
end;
/
show err
```

printing problem in pdf and csv using bind variables
Hello

I created a simple sql statement using a query and bind variables. I noticed when I remove the bind variables and hardcode the values that the CSV/PDF links work. When I handed the return variables in the query, the WB shows "no data found" and pdf shows only the column header.

If anyone can help me, I would be very happy!

Thank you
Ayed P.
Hello

How are set the bind variable? If there are topics evaluated by default on the elements of the page, so is not necessarily enough to ensure that the exports are their values. To set values, I tend to use calculations, conditional that the element is null, what works "Before Header". In this way, the value is stored in the session and is available for export. I think the defaults to be those that are defined when the page is submitted and are not available until now.

Andy

problem with bind variables in the SQL query view object

Hi all
I use JDev 11.1.2.4.0.
I have a problem with bind variables in the SQL query view object.
This is my original SQL
```
SELECT sum(t.TIME) , t.legertype_id
FROM LEDGER t
WHERE t.nctuser_id = '20022' 
      AND to_char(t.insertdate,'YYYYMMDD') in ('20130930','20130929')
group by t.legertype_id
```
In my view .xml object query tab, I am writing this
```
SELECT sum(t.TIME) , t.legertype_id
FROM LEDGER t
WHERE   t.nctuser_id = '20022'
    AND to_char(t.insertdate,'YYYYMMDD') in :dddd
group by t.legertype_id
```
Davis here is a variable of Type liaison: String, updatable and necessary.
I try to deal with Davis as ('20130930 ', ' 20130929') hoping the view object, run as my original SQL.
But failed. The view object retrieves 0 line after that I run.
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Thank you! ('2original SQL0130930', '20130929') ('20130930 ', ' 20130929')

A variable binding cannot be used as this is why you must use years table. Check decompilation binary ADF: using oracle.jbo.domain.Array with ViewCriteria to see a solution.

Timo

Why bind variables/page items does not work in the report query?

Hello world
I am trying to use the page as a bind variable in the query of my report. I checked the box to state of Session and also added my page elements in the LIST of ITEMS in the SESSION STATE.
but NO RECORD not DISPLAYED IN THE REPORT at RUN TIME.
to see live please connect to
http://Apex.Oracle.com/pls/Apex/f?p=52297:LOGIN_DESKTOP:8355343133792
user name: [email protected]
password: 123456

Hello

I looked at the application.

Do you want to go to the report page after click on the report button? If it is, your button to submit the page. Then, you need a branch to access this URL. By submitting the page, your value should be set at the session.

Kofi

The use of bind variables in dynamic query created for Ref Cursor

Hello

I'm in a situation where there is a Ref cursor to which the query is built execution based on a loop. This is why the number of links would be known until the program runs.
The application is currently using literals instead of bind variables.

code snippet of the above is
strSql: = "select * from emp where 1 = 1 and ().

loop cursor1
If cond is true then
strSql = strSql | "ename = ' |" Cursor1.ColumnName;
end loop;

Open cursor2 for strSql;

How to use links in the example above.

sb92075 wrote:

user13019948 wrote:
Hello

Here is the code I have my trying to change literal-based link to the base.

What do you mean by "based bind?

who, what, how determines the values to be 'bound '?

He's referring to the coding style. He is currently using concatenated literal, and the goal is to change it to use the bindings.

If I understand this it is known as method 4 dynamic SQL and requires DBMS_SQL. There are examples autour but they vary according to the type of statement being generated - SELECT statements require column lists to be parsed, unlike the INSERT/UPDATE/DELETE.

This came up recently on my current project and I hit a demo. Here a table of names and values accepted procedure and had to build these in a single WHERE clause along the lines of

AND t_names(i) = t_values(i)

for an undetermined number of elements in the array. For this demonstration, I used a table that we called "attribute" (don't ask) which has columns including 'attribute_id' and 'name', and I need to build a query along the lines of

select description from attribute where attribute_id = :b1 and name = :b2

by the way '1012' and 'ISIN' respectively. (I use a table better and after a CREATE statement for her but I have to rush right now, sorry).

declare
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   t_names           constant varchar2_t := varchar2_t('attribute_id',  'name');
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   l_sql             varchar2(500) := k_sql_base;
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   l_cursor_handle   integer;

begin
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   for i in t_values.first .. t_values.last loop
      dbms_sql.bind_variable(l_cursor_handle, ':b'||i, t_values(i));
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   dbms_output.put_line('Result = ''' || l_value || '''');

   dbms_sql.close_cursor(l_cursor_handle);
end;

Hope that helps...

Query report back "No data found" with bind variables
I put a simple query in the report query:

Select "bluefish". 'name' as 'name',
"bluefish". "" primary_flag "as"primary_flag. "
"bluefish". "" status "than"status. "
"bluefish". ' ' ID ' as 'ID' of "bluefish" "bluefish" where "bluefish". "" ID "=: P3_XPRINTID

When I test the query, the data is returned. However, when I try to run the query using the "Test report" button, I get an error 01403 no data found. If I replace the link with an explicit value variable, the report runs.

Anyone have any ideas as to what is causing this problem? I use the generic report layout, with different types of output. I'M editting the query and set the binding variable before test report (otherwise, the query is not executed).

Charles
In fact the report would go - unlike other products of Oracle who complain about a missing binding variable, Apex is not complaining but interprets as a null value. So if you hurt typed the name of your variable, you are never alerted to it.

Check the Session window to make sure that it is a value - the most common questions are that you named the wrong variable in the query or your item has no value in session state again.

Need help with Bind variable in AF LOV query
Hello

I have a problem with the binding variable, if I use bind variable in the VO LOV query then my result does not come, if he has do not bind variable it works fine and if I use the variable binding in the LOV search option then it works fine but if I hide the bind variable and set the value in the prepareSesstion AM method the LOV does not return any value. I try to return the values that also all values are also coming, but these values are not the attribute query AF setting.

Query is:

Select substr(d.description,0,40) description
cm_system_users has
b cm_user_responsibilities,
cm_responsibility_processes c,
cm_processes d
where a.nt_login =: B_NT_LOGIN
and a.user_id = b.user_id
and trunc (sysdate) between b.eff_date and nvl (b.exp_date, sysdate + 1)
and b.RESPONSIBILITY_ID = c.RESPONSIBILITY_ID
and c.process_type = d.process_type
and d.enabled_flag = 'Y' order of d.arguments_flag

FOLLOW the method:

CmProcessViewImpl vo = getCmProcessView();
String nt_login = getUserPrincipalName();
vo.setNamedWhereClauseParam ("B_NT_LOGIN", nt_login.toUpperCase ());
vo.executeQuery ();

Can someone help me with this. It is urgent for me.
It's a bit underdescribed. IIUC, the purpose of the notice is used as a target for a correct view accessor? (Otherwise, you will have to be more explicit about what you mean by "LOV query".

If I'm right, there are two possibilities:

(1) you use an instance of VO in a module shared application instance. If so, make sure that your code is in the prepareSession() for the class of application that module if it is dependent on session (as seems to be below), you must make sure that the module of the application instance is shared in the session scope.
(2) you have based the view accessor directly on the definition of the VO. This creates an anonymous instance of VO; I don't think there is a way to use prepareSession() to set a variable of liaison on such a forum (which will not be created until the accessor is first used). Pourriez be able to shoot with to put a similar code in the view object create() method class, but I've not tested this.

If your code is in your module class application primary (as opposed to the class for a shared of AOS instance), the problem here is that getCmProcessView() returns the instance of VO data module of this application instance design-time model, which is never used by accessors of the view.

Also, why do you need to do this in prepareSession() rather than at the level of the accessor to view? I believe you can get the user name (for the view accessor) with the groovy expression

viewObject.DBTransaction.session.userPrincipalName

or maybe just

DBTransaction.session.userPrincipalName

(despite this DBTransaction involving, it returns the username web app, not the DB user name).

It is a declarative 100% solution, if you don't count the Groovy expression as not declarative.

If you are afraid of a user who is running the LOV (somehow) before the value of the bind variable is preparing, just make sure that the binding variable is marked "required."

Bind variables improve query performance?
Hello

Bind variables improve the performance of the program or a SQL query.

Select empno, ename, sal from emp where empno =: eno;

Select sal in: emp WNV;

According to these queries I request performance of the bind variable to learn more from you.

Kind regards
Vincent.

Published by: Venkata2 on September 16, 2008 18:40
any variable inside a stored procedure is one of liaison.

the use of bind variables can help you avoid analysis difficult. which leads to the improvement of the performance.

Thank you
Knani.

Estimate of poor cardinality using Bind Variables

Hi I'm using the 11.2.0.4.0 Oracle version. I have a query that is underway for the plan of the poor execution by the estimate of poor cardinality for two tables (I've extracted and published this part only) as I mentioned below, the individual conditions for which the estimate goes bad and moving entire query execution path.

These are for two tables and currently we use BIND variable for them in our code, and I notice, its best estimate gives with literals. I need to know how to handle this scenario that I need this query to execute for all types of volumes. Is there something I can do without changing the code, as it works well for most of the execution? In the current scenario of the main query that uses those below tables providing a plan (index + nested loop) that works very well for small volume, but running for 10 hr + for large volume as ideally its going to the same regime.
And Yes, most time that this request will be hit for small volume, but killing some appearance of large volume presents the performance of the queries.

Here are the values of the variable binding.

B1 VARIABLE VARCHAR2 (32);
B2 VARIABLE VARCHAR2 (32);
B3 VARIABLE NUMBER;
B4 VARIABLE VARCHAR2 (32);
B7 VARIABLE VARCHAR2 (32);
B5 VARIABLE NUMBER;
B6 VARIABLE NUMBER;

EXEC: B1: = 'NONE ';
EXEC: B2: = NULL;
EXEC: B3: = 0;
EXEC: B4: = NULL;
EXEC: B7: = NULL;
EXEC: B5: = 0;
EXEC: B6: = 0;

---- For  TABLE1-------
 -- Published Actual VS Etimated cardinality
 
 
-- With bind values
select * from TABLE1 SF
WHERE (   (SF.C1_IDCODE = :B4) OR (NVL (:B4, 'NONE') = 'NONE'))
    AND ( (SF.C2_ID = :B3) OR (NVL (:B3, 0) = 0));
Plan hash value: 2590266031
-----------------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation                 | Name                | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads  |  OMem |  1Mem | Used-Mem |
-----------------------------------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT          |                     |      1 |        |  28835 |00:00:00.08 |    2748 |     46 |       |       |          |
|*  1 |  TABLE ACCESS STORAGE FULL| TABLE1              |      1 |     11 |  28835 |00:00:00.08 |    2748 |     46 |  1025K|  1025K|          |
-----------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
   1 - storage((("SF"."C1_IDCODE"=:B4 OR NVL(:B4,'NONE')='NONE') AND ("SF"."C2_ID"=:B3 OR NVL(:B3,0)=0)))
       filter((("SF"."C1_IDCODE"=:B4 OR NVL(:B4,'NONE')='NONE') AND ("SF"."C2_ID"=:B3 OR NVL(:B3,0)=0))) 
 
-- With literals 
select * from TABLE1 SF
 WHERE  (   (SF.C1_IDCODE = null) OR (NVL (null, 'NONE') = 'NONE'))
      AND ( (SF.C2_ID = 0) OR (NVL (0, 0) = 0));
   Plan hash value: 2590266031
--------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation                 | Name                | Starts | E-Rows | A-Rows |   A-Time   | Buffers |  OMem |  1Mem | Used-Mem |
--------------------------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT          |                     |      1 |        |  28835 |00:00:00.03 |    2748 |       |       |          |
|   1 |  TABLE ACCESS STORAGE FULL| TABLE1              |      1 |  28835 |  28835 |00:00:00.03 |    2748 |  1025K|  1025K|          |
--------------------------------------------------------------------------------------------------------------------------------------

--------For TABLE2 ----------------------- 
-- Published Autotrace plan, as it was taking long time for completion, and actual cardinality is 45M, but its estimating 49 With bind value---

--withbind value
select * from TABLE2 MTF
WHERE (   (MTF.C6_CODE = TRIM (:B2)) OR (NVL (:B2, 'NONE') = 'NONE'))
  AND (   (MTF.C3_CODE = :B1)  OR (NVL (:B1, 'NONE') = 'NONE'))
  AND (   (MTF.C4_CODE = :B7)  OR (:B7 IS NULL))
  AND (   (MTF.C5_AMT <= :B6)  OR (NVL (:B6, 0) = 0))
  AND (   (MTF.C5_AMT >= :B5)  OR (NVL (:B5, 0) = 0));
Execution Plan
----------------------------------------------------------
Plan hash value: 1536592532
-----------------------------------------------------------------------------------------------------------
| Id  | Operation                  | Name         | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT           |              |    49 | 10437 |   358K  (1)| 01:11:43 |       |    |
|   1 |  PARTITION RANGE ALL       |              |    49 | 10437 |   358K  (1)| 01:11:43 |     1 |  2 |
|*  2 |   TABLE ACCESS STORAGE FULL| TABLE2       |    49 | 10437 |   358K  (1)| 01:11:43 |     1 |  2 |
-----------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
   2 - storage(("MTF"."C4_CODE"=:B7 OR :B7 IS NULL) AND ("MTF"."C3_CODE"=:B1 OR
              NVL(:B1,'NONE')='NONE') AND ("MTF"."C5_AMT"<=TO_NUMBER(:B6) OR NVL(:B6,0)=0) AND
              ("MTF"."C5_AMT">=TO_NUMBER(:B5) OR NVL(:B5,0)=0) AND ("MTF"."C6_CODE"=TRIM(:B2) OR
              NVL(:B2,'NONE')='NONE'))
       filter(("MTF"."C4_CODE"=:B7 OR :B7 IS NULL) AND ("MTF"."C3_CODE"=:B1 OR
              NVL(:B1,'NONE')='NONE') AND ("MTF"."C5_AMT"<=TO_NUMBER(:B6) OR NVL(:B6,0)=0) AND
              ("MTF"."C5_AMT">=TO_NUMBER(:B5) OR NVL(:B5,0)=0) AND ("MTF"."C6_CODE"=TRIM(:B2) OR
              NVL(:B2,'NONE')='NONE'))
  
-- with literal
select * from TABLE2 MTF
WHERE (   (MTF.C6_CODE = TRIM (null)) OR (NVL (null, 'NONE') = 'NONE'))
 AND (   (MTF.C3_CODE = 'NONE') OR (NVL ('NONE', 'NONE') = 'NONE'))
  AND (   (MTF.C4_CODE = null)  OR (null IS NULL))
   AND (   (MTF.C5_AMT <= 0)  OR (NVL (0, 0) = 0))
  AND (   (MTF.C5_AMT >= 0)  OR (NVL (0, 0) = 0));
Execution Plan
----------------------------------------------------------
Plan hash value: 1536592532
-----------------------------------------------------------------------------------------------------------
| Id  | Operation                  | Name         | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT           |              |    45M|  9151M|   358K  (1)| 01:11:41 |       |    |
|   1 |  PARTITION RANGE ALL       |              |    45M|  9151M|   358K  (1)| 01:11:41 |     1 |  2 |
|   2 |   TABLE ACCESS STORAGE FULL| TABLE2 |    45M|  9151M|   358K  (1)| 01:11:41 |     1 |  2 |
-----------------------------------------------------------------------------------------------------------

select column_name,num_nulls,num_distinct,density
from dba_tab_col_statistics where table_name='TABLE2'
and column_name in ('C3_CODE','C4_CODE','C5_AMT','C6_CODE');
C3_CODE 0 65 0.0153846153846154
C4_CODE 0 2 0.5
C5_AMT 0 21544 4.64166357222429E-5
C6_CODE 1889955 71 0.0140845070422535

933257 wrote:

((SF. C1_IDCODE =: B4) OR (NVL (: B4, 'NONE') = 'NONE'))

In fact for literals, I did not find any section of the predicate after running the sql code with activation "set autotrace traceonly explain."

The main problem is with another large query whose cardinality is underestimated due to the presence of these table (table1, table2) with the above mentioned clause, and the query is for the analysis of index + nested with values of Bind loops and take 10 hr +, whereas with literals, its completion in ~ 8minutes with FTS + Hash Join.

Your real problem is that you try to have just a single SQL query handle all POSSIBLE thanks to the use of embedded FILTERS ' either / or ' filters in the WHERE clause. You want only a select this OPTION to run whatever filters have been selected at run time by the user or the application using it. And it would never work. You really need to SELECT different queries for different combinations of filter conditions.

Why? Think for a minute. How Oracle works internally? A SQL SELECT query gets analyzed and an execution plan is produced which is stored in the library cache and gets REUSED on all subsequent executions of this query - except in certain cases where there may exist several plans run through several cursors of the child. So with only SELECT a query you only AN execution plan in the library cache, to be used by all THE executions of this query, regardless of the value of your run-time binding variables.

Lets put another way - each library cache execution plan is associated with a SQL statement. If you want a DIFFERENT execution plan then you need run a DIFFERENT SQL statement. That's how you get a different execution plan - by running a different SQL statement. Running the SAME SQL query generally you will get the SAME execution plan every time.

In addition, because of the "either / or" filters that you use you will end up generally with a full Table Scan on each of the referenced tables. Why? Given that the optimizer must produce an implementation plan that manages all possible contingencies for all values of possible bind variables in the SELECT. If the optimizer should choose to use any index based on one of these "either / or" filters then it would only help performance when real value was provided, but it would be really bad if a NULL value was supplied. If the optimizer ends up ignoring the index because they are not always optimal for all possible input values and instead chose a plan that is "good enough" for all input values possible. That means that it will use a scanning Table full.

I hope you can see that it is precisely what is happening for you with your query. You select this OPTION to manage the different combinations of filter, which leads to the execution plan only one, which leads to scans full Table on the referenced tables in these ' either / or ' filters.

The solution? Build queries SELECT DIFFERENT when input values are NULL. How you do that? Read this article to ask Tom that tells you:

http://www.Oracle.com/technetwork/issue-archive/2009/09-Jul/o49asktom-090487.html

To sum up - when you have real value for a bind variable 'bind_var1' add the following filter to your CHOICE:

AND column_name1 =: bind_var1

When the binding variable is NULL, add the filter according to your CHOICE:

AND (1 = 1 OR: bind_var1 IS NULL)

Now, you'll have 2 queries SELECT must be performed, which have exactly the same number of variables in the same order bind, which is important. When you then run one of these variations, Oracle can analyze and optimize each one SEPARATELY, with a single execution by the SELECT query plan.

When you provide a real value, the filter is a normal 'column = value' that the optimizer can use all indexes on this column, because NULL values are not referenced.

When there is no real value, the optimizer will analyze the '1 = 1 GOLD' and realize that "1 = 1" is set to TRUE and GOLD, it is quite TRUE regardless because the binding variable is null or not. This means that the optimizer will actually REMOVE this filter, because it filters nothing because it is always TRUE. You will end up with an operating plan based on the other filters in the query, which is what you want because you have no filter on this column.

What is it - producing distinct SELECT queries to determine if you have a real value to filter or not you end up with DIFFERENT execution plans for each of them, and each of them is OPTIMAL for this particular set of filters. Now you get good performance for each variation of the performance of the SELECTION, rather than sometimes good and sometimes very bad when using SELECT only one. It is impossible to try to get multiple shots of execution 'optimal' out of a SELECT query. That's why you get mediocre performance under different bound the values of the variables.

John Brady

Estimates of cardinality for index range scan with bind variables

Oracle 11.2.0.4

I am struggling to explain that the cardinality estimates for a scan of the index systematic range when using the bind variable.

Consider the following query:

SELECT /*+ INDEX(t1) */ *
FROM   t1
WHERE  source_id <= ?;

Cardinalities for the INDEX RANGE SCAN and ACCESS of the TABLE are the same for different literal predicates, for example, source_id < = 5:

------------------------------------------------------------------------------------
| Id  | Operation                   | Name | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |      |    50 |   350 |    12   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| T1   |    50 |   350 |    12   (0)| 00:00:01 |
|*  2 |   INDEX RANGE SCAN          | IX1  |    50 |       |     2   (0)| 00:00:01 |
------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - access("SOURCE_ID"<=5)

If a variable binding is used instead of a literal, the overall selectivity is 5%. However, why the optimizer based on CSSTidy gives a cardinality estimated 11 for the scan of the index systematic range? As with the predicates literal, surely the cardinalities of the index range scan and access table should be the same?

------------------------------------------------------------------------------------
| Id  | Operation                   | Name | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |      |    50 |   350 |     5   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| T1   |    50 |   350 |     5   (0)| 00:00:01 |
|*  2 |   INDEX RANGE SCAN          | IX1  |    11 |       |     2   (0)| 00:00:01 |
------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - access("SOURCE_ID"<=TO_NUMBER(:A))

Unit test code:

CREATE TABLE t1
( id NUMBER
, source_id NUMBER
);

CREATE INDEX ix1 ON t1 (source_id);

INSERT INTO t1
SELECT level
     , ora_hash(level,99)+1
FROM   dual
CONNECT BY level <= 1000;

exec DBMS_STATS.GATHER_TABLE_STATS(user,'T1')

EXPLAIN PLAN FOR
SELECT /*+ INDEX(t1) */ *
FROM   t1
WHERE  source_id <= 5;
SELECT * FROM TABLE(dbms_xplan.display);

EXPLAIN PLAN FOR
SELECT /*+ INDEX(t1) */ *
FROM   t1
WHERE  source_id <= :a;
SELECT * FROM TABLE(dbms_xplan.display);

There are various places where the optimizer uses an assumption, and lie unpeekable (and of Villa "unknowable value") introduced guess.

For unpeekable binds the conjecture for column<= {unknown}="" is="" 5%="" for="" table="" access="" (hence="" 50="" rows="" out="" of="" 1,000),="" but="" it's="" 0.009="" for="" index_column=""><= {unknown},="" which="" means="" i="" was="" expecting="" to="" see="" 9="" as="" the="" row="" estimate="" on="" the="" index="" range="">

I just ran some quick tests, and EXPLAIN the PLAN seems to just use 0.011 selectivity in this case (in different versions of Oracle) although if we do the bind variable unpeekable at run time (and sample dynamic block etc.) optimization for execution is 0.009%.

Concerning

Jonathan Lewis

Update: and this is a very old reference to the 0.009 (and 0.0045 for ' between the ' when it is applied to a clue: cost based Oracle - access Chapter 4 single B-tree )

Bind Variables on the view objects child definition

JDeveloper 12 c
I have an interesting question. I have a view (AisWebModulePrivsVO) object that uses a bindvariable hardcoded in the view object.
SELECT * FROM SYS. DBA_ROLE_PRIVS where DEALER =: bvUserName
If I put this in the request module I can programmatically set the variable binding (view object contains the getter/setter for the binding variable).
AisWebModulePrivsVOImpl voTest = am.getAisWebModulePrivsVI ();
voTest.setbvUserName ("ARAWLS");
voTest.executeQuery ();
System.out.println ("test reports:" + voTest.getRowCount ());
and get the correct number of records based on return on the user and database roles. If it works.
What does NOT work, it is when this display object is a recording of 'the child' to another display object (as specified by a link between the two and by setting the object from a point of view as one child of the other in the module of the application).
AppModule looks like this:
CgRefCodesVO
AisWebModulePrivsVO
In this case, I have a view called cgRefCodeVO parent object. There is a link between this and the AisWebModulePrivsVO. The relationship works.
AISMenuAppModuleImpl m = ADFUtils.getApplicationModuleForDataControl (appMod) (AISMenuAppModuleImpl);
CgRefCodesVOImpl cgRefVO = am.getCgRefCodes1 ();
AisWebModulePrivsVOImpl modsVO = am.getAisWebModulePrivs1 ();
modsVO.setbvDBUserName ("ARAWLS"); This doesn't seem to work here...
cgRefVO.executeQuery ();
All lines rs = cgRefVO.getRowSet ();
RS. Reset();
While (rs.hasNext ()) {}
CgRefCodesVORowImpl CgRefRow = rs.next ((CgRefCodesVORowImpl));
System.out.println ("RvLowValue:" + CgRefRow.getAttribute ("RvLowValue"));
RowIterator aisModulesRowIter = CgRefRow.getAisWebModulePrivs ();
System.out.println ("number of children:" + aisModulesRowIter.getRowCount ());
}
The code compiles and runs. She translates: "County of the child: 0" for each row returned by the
I also tried:
VM VariableValueManager = modsVO.ensureVariableManager ();
vm.setVariableValue ("bvDBUserName", "ARAWLS");
And:
modsVO.setNamedWhereClauseParam ("bvDBUserName", "ARAWLS");
and (of https://community.oracle.com/message/2746551#2746551 ( )
@Override
protected void executeQueryForCollection (Object, object, Object [] object2, int i) {}
I coded everything hard to see if it would work.
setNamedWhereClauseParam ("bvDBUserName", "ARAWLS");
super.executeQueryForCollection (object, object2, i);
}
and from there, I changed around the order to execute the objects in view. https://community.oracle.com/message/10632314#10632314
How can I set the variable binding in the object view child?
Thank you
Stuart

It is an interesting example how ADF works up to a certain point... then you need to start to make cuts to modify its behavior as you wish.

I decided that it was just easier to delete 'the child' parent (in the app module) and create a view of criteria on this subject for what would basically query the records to get the same results, like a child.

Perhaps not as elegant, but so much easier.

Thanks for your help.

Stuart

R12 Extension with bind variables-how VO EO

Hello
I extended an APInvDistAllVO view object by adding two fields which are functions. Basically, in the invoice approval screen, I want to add two fields where the distribution of the invoice is shown.
the SQL contained in jdeveloper when you extend the VO object is different from the query, what I see in the invoice approval page by clicking on the APInvDistAllVO link. There are two bind variable: 1 = invoice_id and: 2 = line_number being added dynamically.
After the extension of the view object, the invoice distribution line is displayed as no record found. In my opinion, it is due to not having bind variables does not correct parameters being passed, and under this point of view object is an object depending on the invoice header record.
Will be very grateful if someone can provide the way forward in dealing with this situation.
Rgds
Fahad

User, please ask your question in the forum OA Framework .

Timo

A query on bind variables

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