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• How to change the value of string clustered, to implement using the node value of property instead of writing directly on the flow of data or using the variable

  new to labview :-) and I have a problem when I want to change the value of a string in bunches, and I want to implement this using the node value of property instead of writing directly to the stream or by using the variable, enclosed is the picture.   No matter, I have change in cluster (control) or value of Popery out (indicator) cluster, the value (sensor 7) dataflow keeps unchanged even I gave the new value by value of property node. Thank you to give me some advice about this.

  

  Hi GerdW

  Thanks a lot for your answer. The reason I'm stubbornly tring to break the flow of DATA is: we have a test system that have about 100 screws, they have a few connected flow, some of them will be unbundling a cluster dataflow chain to check the value in order to make the different cases.  Now I want to insert user event by changing the control and influential cases during run time.

  As I initially uses a global variable (to control cases) instead of unbundle string data flow, it works well.  But then, I found there are a lot of screws that are using the string unbundle.  One of the 'lazy' means, I tried is to change the value via the property node (because that way, I did not need to find all the places where using the unbundle string and replace them with the global variable), then I noticed a problem with "dataflow", the value in the stream of cluster in fact will not be changed by changing the value of the property node.

  I did a test with VI simple (like the picture in last post), and after reading your advice, I tell myself that I need to understand the concept of "DATAFLOW" in labview, it seems that my "lazy" way can not work in this scenario.

  I have attached the criterion VI here, have you furthur suggestions on what I can do in this case?

  Mant thanks!

  Minyi

• Why LabVIEW example projects using Global Variables?

  I'm puzzled.  I've been pretty good programmers LabVIEW talks (including some who work for the OR) and came away with the impression that Global Variables should, as a general rule, be avoided, with functional Global Variables (alias VI Globals) generally preferred for "local memory".

  I have studied some of the example distributed with LabVIEW, 2012 and 2013, in particular the proposed acquisition in real time and am struck by the use of Global Variables, where I'd be inclined to use instead a FGV.  For examples, to stop all the loops on the RT target, the overall "All the RT loop Stop" is defined; 'Constants' of configuration (such as timeouts, Streme network names, the names of the journal folder) are kept as Globals; Streme network endpoints are stored in Globals.

  [Note - there is a weird spelling of the second word of the network Streme, above - when I tried to post with the correct spelling, I got an error message saying this word is 'not allowed in this community".]  I apologize for the offense, but I must confess that I do not understand what the problem with the help of the spelling of this word...]

  Why use Globals in these cases, rather than write a bunch of VIGs to hold these data?  Note that almost all these Globals are 'Read' essentially (written once when a resource is acquired, for example) or "Read Only" (treated as if they were a constant).  Indeed, read-only variables can be written as a Subvi with only an output terminal, acting as a (visible, due to the icon) constant.

  I can see advantages to this approach.  On the one hand, VIGs can have error bounds who run the data flow (I just spotted a bug "data flow" in code, I am developing that is based on this model, to read configuration data to an XML file in a world and in the same VI, Global wiring to a "use - me" terminal, but with no guarantee that I'll read the overall after I write it).

  It is, I suppose, a matter of 'speed' - perhaps Global Variables are 'faster' than VIGs (especially if the VIG 'sits' on an error line).  My thought, however, is that this difference is likely to be trivial, especially as these VIGs (or Globals) tend to become "occasional" calls (with the exception of the indicator 'all the loop Stop' which is called once per line).

  Are there other arguments or considerations that make a Variable global to a better choice than a VIG?  Is there a reason that LabVIEW developers put in these start-up of projects LabVIEW?

  BS

  I have to ask, how do you use functional Global Variables?  Like just a Get and Set?  If so, you can use a global variable.

  Yes, globals are faster and use much less overhead.  At the summits of CLA in recent years, we talked about using globals.  The most common use is for Write-Once-Read Many and writing-never-Read Many with configuration data.  It's a good idea to use globals with the constants that can change on you.  It turns out that the world will have the same performance as a constant in this case.  This is done so that you don't have 1 place to edit the 'constant '.

  The rule on "Globals are evil" actually goes back several years when NEITHER had the huge "people of the country are bad" vendata.  But NEITHER explains well how to do things properly.  So I found people, instead of using local variables, using the value property node.  It's even worse because the property causes thread swaps and kills your performance.  It wasn't until I shouted to people to use wires and shift registers I have seen improvements in the way in which people wrote their code.  So people are always riffling in the use of globals and decided to use FGVs with the EEG and fixed rather cases.  But this does not solve the problem of the conditions of race with critical data and you cause an additional burden.

  So from my experience, I use globals all the time for configuration data.  Yes, you must be careful about the race conditions.  But as long as you understand that it is a common and useful practice.

  I would not use a global variable for data that are constantly changing (use registers to offset or Action motor) and/or processes that have critical sections of code (use a motor of Action).

  NOTE: I use the definition of Mercer to FGV (a Get/Set only) and motor Action (many cases which specifically affect the data).

• Business rule - unable to name the text data using substitution variables

  Hello
  
  I can't assign a value of text stored in a variable substitution. I read the posts that you can't assign string values I just want to check if it was possible using substitution variables.
  
  For example.,.
  
  Trouble (scenario, Version and year)
  
  "Test year".
  (
  "Test year" = &;
  );
  
  EndFix
  
  & those is a substitution variable whose value is "FY13.
  
  Please advice.
  
  Thanks, Cz

  The same rules apply, you must apply a numerical value, because this is what is stored in essbase data compared to the intersection.

  See you soon

  John
  http://John-Goodwin.blogspot.com/

• Execution plan will change if I use the variable binding instead of the literal value?

  Hi guys,.
  
  Suppose I have a select "... Of... WHERE ID = 2 and... "if I go to use the variable binding instead of the literal value 2," SELECT... " Of... WHERE ID =: p_id and... ", the execution plan change?
  I test multiple statements, the plan does not change, but I don't know if it would even as well as in some other cases.
  Someone at - it ideas?
  
  Thank you very much.

  Anneso wrote:
  Hi, sorry for the unclear post, it's 11 GR 2.

  As Sybrand already mentioned, there are a lot of change that came in the implementation of the bind variable in some versions of Oracle db. Since you're on 112, it is still true with the introduction of Adaptive Cursor Sharing . Please have a read on it since the post below written by the development of Oracle optimizer group.
  http://blogs.Oracle.com/optimizer/entry/why_are_there_more_cursors_in_11g_for_my_query_containing_bind_variables_1

  Aman...

• Can I use a variable in a slider?

  Version of DB 10g
  Developer SQL 3.
  
  Hi once again, everything
  
  This post is a result of the post previous 'Sequence increment by 2 and not 1.'
  
  Here's a quick run down of what I do.
  We have historical records dating back decades and decades and decades (1900). Some of the most recent data were recorded in the worksheets. With some manipulation of data, it was possible to reorganize the data in its forms of entry in a flat file. These data were then imported into Access database, then using SQL Developer I made a data base for each access database connection and used copy for Oracle... tool to create a table in my flat file schema. In test data that I have right now that I copied the 5 access to Oracle databases and the results are five paintings called plot_84, plot_151 etc. I created a database that contains four main tables where the data from the flat files must be inserted, to standardize the it (I think the sentence is).
  
  I with the help of a large number has been able to train the following anonymous block, and it works very well (with the exception of the question of sequencing).
  
  

  DECLARE get_plot_measurement_id NUMBER;
  update_plot_measurements VARCHAR2(4000);
  get_tree_id NUMBER;
  get_plot_id NUMBER;
  
  BEGIN
      --1. Initiate insert process by getting PK from psp_plots
      SELECT plot_id INTO get_plot_id FROM psp_plots WHERE plot_name = 84; 
      
      --2. Insert records into psp_plot_measurements and keep relationship with psp_plots with variable get_plot_id.
      --   and get primary key value of psp_plot_measurements to insert into psp_tree_measurements during loop process.
      INSERT INTO psp_plot_measurements (plot_id) VALUES (get_plot_id) RETURNING plot_measurement_id INTO get_plot_measurement_id;    
      
      --3. Update record created at point 2.
      UPDATE psp_plot_measurements
         SET measurement_date    = (SELECT DISTINCT measurement_date FROM plot_84)
           , codominant_height   = (SELECT DISTINCT codominant_height FROM plot_84)
           , assessor            = (SELECT DISTINCT assessor FROM plot_84)
       WHERE plot_measurement_id = get_plot_measurement_id
       ; 
    
      --4. Open cursor to insert rows one at a  time and maintain relationships between related tables.
      FOR c1 IN
        (SELECT tree_number 
           FROM plot_84
        )
        
        LOOP      
      
          --5. Insert record into psp_trees
          --   and get primary key value of psp_trees to insert into psp_tree_measurements
          INSERT INTO psp_trees (plot_id, tree_name) VALUES (get_plot_id, c1.tree_number) RETURNING tree_id INTO get_tree_id;
      
          --6. Insert records into psp_tree_measurements and keep relationship with psp_trees with variable get_tree_id.
          INSERT INTO psp_tree_measurements (plot_measurement_id, tree_id) VALUES (get_plot_measurement_id, get_tree_id);
      
        END LOOP;
  
  END;
  /

  But me being someone who loves jobs mind numbing again and again, and more (about 1000 times x, who knows) still wants something I can preload a list of arrays of flat file (5 in this example) and just not run it.
  
  The problem is the following:
  Can I use a variable in a cursor, how are hilighted in bold below.
  
  "BOLD" has not worked is the bit of code FOR c1 IN (SELECT tree_number FROM plot_ | col_name_var) you will see just under point 4 below
  

  DECLARE p_column_num NUMBER;
  col_name_var VARCHAR2(30);
  type number_ptb IS table OF VARCHAR2(4000);
  p_column_nam number_ptb;    
  get_plot_measurement_id NUMBER;
  update_plot_measurements VARCHAR2(4000);
  get_tree_id NUMBER;
  get_plot_id NUMBER;
  
  BEGIN
  
      p_column_num := 5;
      p_column_nam := number_ptb();
      p_column_nam.extend(6);
  
      p_column_nam(1) := 84;
      p_column_nam(2) := 151;
      p_column_nam(3) := 152;      
      p_column_nam(4) := 214;
      p_column_nam(5) := 283;
  
      FOR loop_int IN 1 .. p_column_num
      LOOP
  
        col_name_var := p_column_nam(loop_int);
  
  --1. Initiate insert process by getting PK from psp_plots
        SELECT plot_id INTO get_plot_id FROM psp_plots WHERE plot_name = col_name_var; 
      
  --2. Insert records into psp_plot_measurements and keep relationship with psp_plots with variable get_plot_id.
  --   and get primary key value of psp_plot_measurements to insert into psp_tree_measurements during loop process.
        INSERT INTO psp_plot_measurements (plot_id) VALUES (get_plot_id) RETURNING plot_measurement_id INTO get_plot_measurement_id;    
      
  --3. Update record created at point 2.
        update_plot_measurements := '
        UPDATE psp_plot_measurements
           SET measurement_date    = (SELECT DISTINCT measurement_date FROM plot_' || col_name_var ||')
             , plot_size_10_30cm   = (SELECT DISTINCT plot_size_10_30cm FROM plot_' || col_name_var ||')
             , plot_size_30_50cm   = (SELECT DISTINCT plot_size_30_50cm FROM plot_' || col_name_var ||')
             , plot_size_50cm      = (SELECT DISTINCT plot_size_50cm FROM plot_' || col_name_var ||')
             , codominant_height   = (SELECT DISTINCT codominant_height FROM plot_' || col_name_var ||')
             , assessor            = (SELECT DISTINCT assessor FROM plot_' || col_name_var ||')
         WHERE plot_measurement_id = ' || get_plot_measurement_id
         ;
   
         EXECUTE IMMEDIATE update_plot_measurements;
    
  --4. Open cursor to insert rows one at a  time and maintain relationships between related tables.
        FOR c1 IN (SELECT tree_number FROM plot_|| col_name_var )   
            LOOP      
      
  --5. Insert record into psp_trees
  --   and get primary key value of psp_trees to insert into psp_tree_measurements
              INSERT INTO psp_trees (plot_id, tree_name) VALUES (get_plot_id, c1.tree_number) RETURNING tree_id INTO get_tree_id;
      
  --6. Insert records into psp_tree_measurements and keep relationship with psp_trees with variable get_tree_id.
              INSERT INTO psp_tree_measurements (plot_measurement_id, tree_id) VALUES (get_plot_measurement_id, get_tree_id);
      
            END LOOP;
    END LOOP;
    
  END;
  /

  Reviews on my welcome code.
  
  Ben
  
  Published by: benton on Sep 1, 2011 11:31
  
  Published by: benton on Sep 1, 2011 11:32
  
  Published by: benton on Sep 1, 2011 11:34

  with your current model, you need to write once for each table or write dynamic SQL regardless of the bulk of collect. adding most collect simply means you can do all the inserts in a single step and generally average performance benefits (see docco to COLLECT in BULK and for ALL).

  However, it is not really solve your problem.

  can I suggest an ETL step where you move all of the data in a table, then cross and run this function on all resulting?

• Text added to the text field using the variable does not appear

  Hello

  I have a test field I created dynamically.  If I add some text to it by writing: myField.text = 'text', the text if poster, but if I add text using a variable is nothing.  If I trace trace text in the text field ("text =" myField.text) get good value.

  Someone at - it ideas?

  Best regards

  Chris McLaughlin

  Try to comment out the two lines below and see if it helps...

  ["textField" + guestCueCnt 'c'] .defaultTextFormat plus myFormat;
  ["textField" + guestCueCnt + 'c'] .embedFonts = true;

• Using global variables in a device custom

  Hello world

  I have problems with the passing of data through my device customized using global variables. I want to allow a user to select a RIO device address when you set up the system definition file. This is recorded in a global variable using the hand Page VI. I would later use this RIO device address in RT driver to deploy a bitfile. I can hard-code, but it is much more convenient to use a global.

  When I try to store the address of the global variable, it updates the value temporarily (I confirmed that the structure of the event recognizes the change of value). When I click the node of the tree to define system linked to the Main Page VI and then click on it again, the hand Page VI runs again. I wrote the code to repopulate the address of device of RIO with the last value stored in the global variable, but it is empty. I've included the VI global variables in my build, so I can't imagine why it can reset this value.

  Any help would be appreciated!

  Thank you

  Mitch

  Have you tried to use the custom device properties to store this value instead of GVs?

  Configuration VI, you can set this property, and if I'm not mistaken, you can read these properties on the RT driver.

• WARNING: Incompatible Arg. You can't use stack Variables If generating series is not defined

  What does this message mean?

  "WARNING: incompatible Arg. you can't use stack Variables If generating series is undefined."

  Where can I put generate series only?

  Thank you

  Derek

  Hi Derek,.

  Not all LabVIEW C Generator settings are compatible with each other. In this case, you must define generate series only (aka 'disable parallel execution') If you want to generate the code uses the variable stack.

• Use the variable based on Chncalculate to tiara

  I need to use a variable in the ChnCalculate function but only takes the text then how to incorporate the varaible in text inside this function. It keeps on undefined variable beep where, as I have already defined at the beginning of the program and also value.

  Hi coolguru,

  The syntax error is in your first line, it should be instead:

  GlobaDim "a".

  Brad Turpin
  Support Engineer product DIAdme
  National Instruments

• Use of Variables shared with RT-project / home-VI

  Hi all

  I have a small question which is certainly easy to answer for those who have already worked with a RT - VI containing two periods loops and a user interface that is deployed on a host PC.

  Q: is there an advantage to the data acquisition in the urgent loop by using a variable shared unique process (active FIFO) and then through the data on the host computer the nondeterministic loop simply through a shared network-published (new FIFO active) variable that directly passes the data on the host PC?

  Thanks in advance,

  David

  Hi Kolibri,

  The advantage of having the network publishes the variables in your non-deterministic loop as opposed to the evanescent loop is that it reduces the resources needed to perform the evanescent loop.

  Send the data to a different loop in the same program with unique shared variable or process with RT FIFOs requires fewer resources than to send data over the network. This allows the loop of high priority execute more deterministic way, without having to manage communication networks.

  Kind regards

  Stephen S.

• Can I use a variable in step of TS Message for field 'waiting time '?

  Is it possible to use a variable (inhabitants, parameters, etc.) for the field "Wait time" in the stage of message TestStand?

  TestStand 4.1

  Thank you

  Rafi

  Go to the step settings > properties > Expressions > Expression Pre and enter something like:

  Step.TimeToWait = Locals.MyTimeToWait

• Limit set using the variable

  IAM having the following query to load the data of my DataModel

  DataSource {
              id: firstSource
              source: "db/duDatabase.db"
              query: "SELECT title FROM how_to ORDER BY howToId ASC limit 10"
              onDataLoaded:
                  {
                      firstModel.insertList(data);
                  }
             }
  

  My Question is:

  How can I use a variable to set the limit in the query

  That is to say, I want something like that

   query: "SELECT title FROM how_to ORDER BY howToId ASC limit variableName"
  

  Please please help me. IAM stuck here.

  query: "SELECT title OF how_to ORDER BY howToId limit of ASC"+ NomDeLaVariable"

• 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

• How many times can I use a variable binding in a query of the VO?

  Is it possible that I can use a variable binding in a query of VO just once?

  I test a query that keeps throwing the Houston-27122 error by pressing the application module tester. I tried to limit the problem to the simplest possible case, and it seems that the error is caused by the fact that I use the same variable bind two or more times.

  When the query looks like this:

  

  I have run, enter 'x' and it returns me the result.

  When I change to:

  

  I have run, enter the value

  

  and immediately get the error

  

  The same thing in sqlplus runs without problem:

  

  My version of JDev is build JDEVADF_11.1.1.9.0_GENERIC_150314.0718.6673

  Please, advise.

  P. S. where can I find documentation queries are supported in your? In particular, I'm interested if I can use WITH the clause. There seems to be some confusion on this matter (see, for example, Oracle SQL WITH clause support - JDeveloper and ADF)

  Thank you.

  It depends on:

  Open your VO in JDev and go the the query page.

  In the lower part, there is a drop down 'link type', it is usually set to "JDBC-positional. In this case, you will need to provide the bind value for each occurrence of the variable binding separately.

  You could change that to "named" (don't remember the exact name). But beware, this will also affect all relatioships master retail to others your. I think that this is not a good idea to change the style of binding to a single VO.

  Good bye

  DPT