Similar Questions

• What is the difference between primary key and unique indexes with forced not null?

  Primary key is = unique index + not null?

  The short answer is Yes.

  However, even if the primary key, applying both uniquness and not null, there is a notion of "special".

  You can only have one primary key in tables, but you can have multiple unique indexes and constraints not null.

  See: https://asktom.oracle.com/pls/asktom/f?p=100:11:0:P11_QUESTION_ID:8743855576462

• Can check and not Null added to the names Administration constraints?

  I don't know if this is the right place to make a request for improvement, but it would be possible to add "and not Null Check constraints" in Tools-> object names Administration?

  It would be extremely useful for those who use them and also apply naming rules.
  Thank you

  

  I logged an ER

  Philippe

• Index Bitmap and MV in Standard edition

  Salvation of DBA
  
  I have an enterprise edition 10.2.0.3 database which can be transformed into 11.2.0.3 EE. There many Materialized view with activated query rewrite. If I downgrade to the standard edition, what will be the impact? I know the rewrite of the query is a feature of EA and not SE and SEO. It is also the index Bitmap in the database which I think must be re-created as the normal b-tree index.
  
  I know that bitmap is not a feautre of the SE. One advantage that I see that updates will be faster if there is a normal index as DML are slow, if there is a Bitmap index.
  
  What will be the impact on the performance of the database if there is standard edition which does not rewrite of the query and the characteristics of Bitmap?
  
  Thank you
  
  DBA is the hero behind the screen, while developers are heroes on the screen.

  user13368428 wrote:
  I went through this table before posting my first post. I don't know there are a lot of tables in my EE database that contains bitmap indexes. In the past, I turned on the control over some of them, and they have been used. Also, I have seen queries that are rewritten to use the MV table instead of the base of fact tables.

  Yes. Really, I need to test in decommissioning and annexing the request to it. But I wanted to know if anyone has experienced this. What were their experiences do not use Bitmap indexes, function index and Query rewrite.

  Your response was very useful.

  Thank you.

  The Oracle Server Standard edition supports function based indexes (I think since version 8.1.5). Bitmap indexes are not supported and treat B * index of tree as the index of the bitmap to bitmap join operations are also not supported. You can partially determine the impact of not having the second option by editing a hidden at the session level setting (obvious caveat on masked editing settings apply here):

  ALTER SESSION SET "_B_TREE_BITMAP_PLANS" = FALSE;
  

  I'm fairly certain that the Standard Edition supports materialized views - automatic query simply not rewrite for possibly enjoy this feature based on cost.

  There may be a few other surprises, here is part 1 of 4 that explores the potentially unexpected differences between Standard Edition and Enterprise Edition (the differences are version and OPTIMIZER_FEATURES_ENABLED load):
  http://hoopercharles.WordPress.com/2010/11/21/different-performance-from-Standard-Edition-and-Enterprise-Edition-1/

  Good luck to you with the project.

  Charles Hooper
  http://hoopercharles.WordPress.com/
  IT Manager/Oracle DBA
  K & M-making Machine, Inc.

• Hide/show text when field null and not null

  I discovered how only display a field in a query using Dreamweaver 8, PHP, and MySQL when the value of the field is zero in showing this:
  http://www.Adobe.com/cfusion/webforums/Forum/MessageView.cfm?forumid=12 & catid = 189 & ThreadID = 1005921 & arctab = & highlight_key = y & keyword1 = see the % 20region
  
  However, how can I put text next to the field data when there are data in the field? Therefore, 1) hide textes_ data when the value in the record field is zero and 2) show text data and when the fields of records is not null.
  
  I tried to put the text with the echo, but then the text is displayed without the data from the field when the field is null.
  
  The code I have so far is:
  <? PHP if (! is_null ($row_rsProperties ['US_List_Price'])) {echo $row_rsProperties ['US_List_Price'] ;}? >
  
  rsProperties is the recordset and US_List_Price is the field
  
  Thank you!
  

  dulcey1 wrote:
  > I tried to format the text with the echo, but then the text is displayed
  > without data field when the field is null.
  >
  > The code I have so far is:
  >
  > $row_rsProperties ["US_List_Price"] ;} ?>

  The is_null() function checks a NULL value. I suspect that your
  the fields are empty instead of NULL. Change the code to do this:

  
  "Text". $row_rsProperties ['US_List_Price'] ;} ?>

  --
  Adobe Community Expert David Powers
  Author, "Foundation PHP for Dreamweaver 8" (friends of ED)
  Author, "PHP Solutions" (friends of ED)
  http://foundationphp.com/

• index bitmap and separate key

  Hi guys,.
  
  If the separate keys is very low (for example 20) and my index finger has more than 12,000 lines, should I consider using a bitmap index instead?
  
  Thank you

  OracleGuy777 wrote:
  But that say our table was very fragmented, would not--what it means that the bitmap index entries would be to store much more information than necessary? Say so we had a table with only 1000 entries and the first rowid is 1, and the last was 1000000 and then eventually we have 999000 additional entries for each bitmap index entry!

  Bitmap indexes are well compressed. So, this usually isn't a problem. An example...

  SQL> create table t as select rownum id from dual connect by level <= 1000000;
  
  SQL> execute dbms_stats.gather_table_stats(user,'t')
  
  SQL> select blocks from user_tables where table_name = 'T';
  
      BLOCKS
  ----------
        1557
  
  SQL> delete t where id between 500 and 999500;
  
  999001 rows deleted.
  
  SQL> commit;
  
  SQL> create bitmap index i on t (id);
  
  SQL> select distinct_keys, blevel, leaf_blocks from user_indexes where index_name = 'I';
  
  DISTINCT_KEYS     BLEVEL LEAF_BLOCKS
  ------------- ---------- -----------
            999          1           4
  

  Notice how the index has only 4 blocks of leaves...

  So you're saying something like

  FEMALE 1 0 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 0 0 0 1

  could be stored as

  FEMALE 1 0 0 0 1 1 0 1 0 1 for rowid a to j
  FEMALE 0 1 1 1 1 0 0 1 0 0 0 1 for rowid k - w

  Yes.

  HTH
  Chris Antognini

  Troubleshooting Oracle, Apress 2008 performance
  http://top.Antognini.ch

• Copy vectors as bitmap and not svg

  Hello

  I used to copy vectors from illustrator to software such as Axure, cmd + c and cmd + v. It worked well enough until the CC.

  Illustrator CC copies only the vectors as SVG objects. So when you're in Axure, it copies the SVG code rather than the bitmap object! I understand the need for such a thing in HTML (although I doubt it will be used often), but I have not found any turnaround to be able to copy this vector inside Axure, which is, in my opinion, the greatest use of the feature of copy in illustrator on any other software (like Word for example, which also copies the SVG code rather than the bitmap object)...

  Is it possible to copy the bitmap instead of the SVG code object?

  Thank you!

  Update published 17.1 today for Illustrator CC contains a preference to disable 'Code SVG' copy to the Clipboard, uncheck this option to disable the SVG code copy it to the Clipboard.

  This should solve the copy paste from Illustrator to Axure

  

  -Rama

  Illustrator team

• BUG Apex4.0 AnyChart: apex_util.flash - back to zero, and not null

  [Line graphic screenshot | http://www.anaruk.com/linechart.jpg]
  
  The image of the chart I linked above is a year to the year sales charts. The first series returns the 2009 turnover. The second returns year to date in 2010. The problem is that even if the query returns no data from August to December 2010 - because they have not yet - arrived the XML returned by the proc apex_util.flash returns this month with a zero value causing the graph plot these data.
  
  game of 2009 query results:
  MONTH IN LINK SALES
  -Jan 250
  -Feb 230
  -Mar 360
  -Avr 130
  -120 may
  -Jun 180
  -Jul 130
  -Aug 280
  -270 Ms
  -Oct 250
  -Nov 360
  -Dec 410
  
  2010 query result set:
  MONTH IN LINK SALES
  -Jan 130
  -Feb 970
  -Mar 170
  -Avr 140
  -May 110
  -230 Jun
  -Jul 440
  
  XML for 2010 is back:
  < name of series = "CDA 2010" type = "line" color = "0x1D8BD1" > "".
  < point name = "Jan" y = "130" >
  < / point >
  < point name = "February" y = "970" >
  < / point >
  < point name = "Mar" y = "170" >
  < / point >
  < point name = "Apr" y = "140" >
  < / point >
  < point name = 'May' y = '110' >
  < / point >
  < point name = 'June' y = '230' >
  < / point >
  < point name = "Jul" y = "440" >
  < / point >
  < point name = "August" y = "0" >
  < / point >
  < point name = "Sep" y = "0" >
  < / point >
  < point name = "October" y = "0" >
  < / point >
  < point name = "Nov" y = "0" >
  < / point >
  < point name = "Dec" y = "0" >
  < / point >
  < / series >
  
  
  IF I edit and load the following, AnyChart correctly do not draw the last four months:
  < name of series = "CDA 2010" type = "line" color = "0x1D8BD1" > "".
  < point name = "Jan" y = "130" >
  < / point >
  < point name = "February" y = "970" >
  < / point >
  < point name = "Mar" y = "170" >
  < / point >
  < point name = "Apr" y = "140" >
  < / point >
  < point name = 'May' y = '110' >
  < / point >
  < point name = 'June' y = '230' >
  < / point >
  < point name = "Jul" y = "440" >
  < / point >
  < point name = "August" y = "" >
  < / point >
  < point name = "Sep" = "" >
  < / point >
  < point name = "October" y = "" >
  < / point >
  < point name = "Nov" y = "" >
  < / point >
  < point name = "Dec" y = "" >
  < / point >
  < / series >
  
  --------------------------------
  
  Thanks for any comments.
  
  Walter
  
  Published by: WannaRock on July 23, 2010 14:17
  --------------------------------------------------------------------------
  -being more descriptive
  -correction of the errors of three strikes

  Hi Walter,

  Thanks for that bring to our attention. The behavior you reported is the current default behavior to handle null values on the chart, where they are represented as a zero in the data series. I appreciate this manipulation is not what you expect, especially in your scenario, when you do not want to represent some points on the graph (August - December 2010), so I'll review this behavior and includes a fix for this in our next version 4.0.1 patch. I connected the bug 9945462 to follow up on this matter.

  Kind regards
  Hilary

• B - Tree and explanation Index Bitmap

  Hi gurus

  I am trying to absorb the notion of bitmap index and b-tree, but unable to grasp the concept, so far, I have learned the following:

  Index B-Tree

  Use in the OLTP environment

  It is customary for these types of columns where you have more unique value or we can say that high cardinality

  It occupies less storage

  Using the corresponding model and ranges

  By default, Oracle uses tree indexing

  Bitmap index

  Use in home environment/OLAP data items

  It is customary for these types of columns where repeated values exist or we can say that low cardinality, example are male and female

  It seems that these points of difference between the two indexes. I really appreciate if someone give me more explanation on these subjects.

  Thanks in advance

  Concerning

  Muzz

  I am trying to absorb the concept index bitmap and tree but unable to grasp the concept,

  Then the FIRST place to look is the Oracle documentation; specifically the chapter "Index and Index-Organized Tables" chapter of the Concepts doc.

  http://docs.Oracle.com/CD/E25054_01/server.1111/e25789/indexiot.htm

  3 indices and Index of Tables

  This chapter deals with indices, which are schema objects that can speed up access to the lines of the table and organized index of tables, which are tables stored in an index structure.

  This chapter contains the following sections:

  • Overview of index
  • Overview of the Tables organized by Index

  This chapter has a lot of basic information on ALL the various types of indexes.

  so far, I've learned the following:

  Where, exactly, 'have you' who? Most of it is wrong, incomplete or distorted.

  Index B-Tree

  Use in the OLTP environment

  Index B-Tree, by default, are used in all environments.

  It is customary for these types of columns where you have more unique value or we can say that high cardinality

  They can be used for a cardinality. True - a unique column index is most commonly used for high-cardinality columns. But Oracle may also use an index column, simple or composite, when the data being sought is ENTIRELY contained in one or more indexes, low cardinality.

  It occupies less storage

  Maybe, maybe not. It is based on the column being indexed, the size of the key values and the cardinality of the key values. For your example "Male and female" there will be only THREE index entries: male, female and null. And each entry is simply a list of ranges of ROWID. This index can be orders of magnitude smaller than the equivalent B-Tree index.

  Using the corresponding model and ranges

  For the most part correct - although the range queries can be used with the bitmap index which is not a common use.

  By default, Oracle uses tree indexing

  Fix.

  Bitmap index

  Use in home environment/OLAP data items

  Especially correct - DML on tables with the bitmap index can cause severe performance and throughput problems. The distinction is therefore between environments with medium/high DML on a table compared to the weak or nonexistent DML on a table.

  So rather than a distinction between environments (OLAP and warehouse) the distinction is no longer between the TABLES (high/medium DML versus LOW/NO DML). There is nothing wrong at all with the help of the index of the bitmap in an OLAP environment - but these indices should be limited to the tables with low, or no, DML.

  It is customary for these types of columns where repeated values exist or we can say that low cardinality, example are male and female

  Yes and no.

  Yes - a bitmap index is not really appropriate, if there is NO repeat value.

  No - part II (low cardinality). The attribute MAJOR missing from what you have posted is that bitmap indexes are ALMOST always used in conjunction with others (usually a bitmap) index.

  If one, or more, high cardinality bitmap index can be used VERY effectively together to identify a set of rows to a query.

  See my multiple responses in this thread

  https://community.oracle.com/message/10219613?

  One of my answers presents, in detail, just how many attributes can be combined using several bitmap on both high columns index and low cardinality.

  In a later response, I provide the actual sample code and display the execution plan indicating how Oracle just that.

  SQL> set serveroutput on
SQL> set autotrace on explain
SQL> select rowid from star_fact where
  2   (state = 'CA') or (state = 'CO')
  3  and (age = 'young') and (marital_status = 'divorced')
  4  and (((summer_sport = 'baseball') and (softdrink = 'pepsi'))
  5  or ((summer_sport = 'golf') and (beer = 'coors')));


  Read the full thread.

• Distinguish NOT NULL constraints Check constraints

  Join user_constraints to user_cons_columns for constraint_type = 'C' indicates the Check constraints, and NOT NULL constraints, but also (because those are implemented as Check constraints).
  
  My question is how to filter constraints NOT NULL to let only the 'normal Check constraints '?
  
  I tried WHERE SUBSTR(search_condition,-12,12) & LT; & GT; 'IS NOT NULL '.
  but as search_condition is of type LONG, I can't use substring.
  
  Has anyone already found it? Thank you!!

  ByronBarton wrote:

  Has anyone already found it?

  Well, there is no easy way. Simple, if you always create named* validation constraints. If so, online NOT NULL constraint will get name generated and forced check no:

  SQL> create table test_tbl(
    2                        c1 number not null,
    3                        c2 number,
    4                        constraint test_tbl_chk1
    5                          check(
    6                                c2 is not null
    7                               )
    8                       )
    9  /
  
  Table created.
  
  SQL> select  constraint_name,
    2          generated
    3    from  user_constraints
    4    where table_name = 'TEST_TBL'
    5  /
  
  CONSTRAINT_NAME                GENERATED
  ------------------------------ --------------
  SYS_C008666                    GENERATED NAME
  TEST_TBL_CHK1                  USER NAME
  
  SQL> 
  

  However, if the check constraint is not named we:

  SQL> create table test_tbl(
    2                        c1 number not null,
    3                        c2 number,
    4                        check(
    5                              c2 is not null
    6                             )
    7                       )
    8  /
  
  Table created.
  
  SQL> select  constraint_name,
    2          generated
    3    from  user_constraints
    4    where table_name = 'TEST_TBL'
    5  /
  
  CONSTRAINT_NAME                GENERATED
  ------------------------------ --------------
  SYS_C008668                    GENERATED NAME
  SYS_C008669                    GENERATED NAME
  
  SQL> 
  

  Then, the only way I know is:

  SQL> column owner format a10
  SQL> column table_name format a10
  SQL> column column_name format a10
  SQL> select  u.name owner,
    2          t.name table_name,
    3          a.name column_name,
    4          c.name constraint_name,
    5          decode(k.type#,7,'NOT NULL',1,'CHECK CONSTRAINT','UNKNOWN') type
    6    from  sys.USER$ u,
    7          sys.CON$  c,
    8          sys.CDEF$ k,
    9          sys.OBJ$ t,
   10          sys.COL$ a,
   11          sys.CCOL$ r
   12    where u.name   = user
   13      and c.owner# = u.user#
   14      and k.con#   = c.con#
   15      and t.obj#   = k.obj#
   16      and t.name   = 'TEST_TBL'
   17      and a.obj#   = t.obj#
   18      and r.col#   = a.col#
   19      and r.con#   = k.con#
   20      and r.obj# = k.obj#
   21  /
  
  OWNER      TABLE_NAME COLUMN_NAM CONSTRAINT_NAME                TYPE
  ---------- ---------- ---------- ------------------------------ ----------------
  SCOTT      TEST_TBL   C1         SYS_C008668                    NOT NULL
  SCOTT      TEST_TBL   C2         SYS_C008669                    CHECK CONSTRAINT
  
  SQL> 
  

  SY.

• The doc is correct on the constraint not null and scan limited index full?

  Gave birth to the large [url http://forums.oracle.com/forums/thread.jspa?messageID=9313643] another thread:
  

  Jonathan Lewis wrote:
  >
  

  I wasn't expecting to see because the doc said about scan limited index full "...". and at least one column in the index key has the NOT NULL constraint,"which would be foolish to say if the rowid was what filled that. There are currently only 2 factory codes and code 1 company (not nulls - Oracle does know that?), so I was kind of expected Oracle to reorder the predicates with an index skip scan. Take a fresh look on the doc, I wonder if I should not specify the company code in the query and maybe spend employee and job_number in the index. I hope it's obvious that this index has been added for other queries. This request could be taken out a change in the requirements of anyway, but I don't know when.

  If you wear it as a separate thread, I'll take a look.
  Can you give a reference to the manual - the comment you quoted may not be correct.

  Just below where Hemant pointed to in the other thread, http://download.oracle.com/docs/cd/E11882_01/server.112/e16508/indexiot.htm#sthref314
  
  (Somehow I have the feeling that we had this conversation before, perhaps in a forum that no longer exists. "(Or was it all just a dream)."
  
  Edit: Also seen in
  http://download.Oracle.com/docs/CD/B28359_01/server.111/b28274/optimops.htm#i52044
  http://download.Oracle.com/docs/CD/B14117_01/server.101/b10752/optimops.htm#51111
  http://download.Oracle.com/docs/CD/F49540_01/doc/server.815/a67781/c20b_ops.htm#11004
  http://download.Oracle.com/docs/CD/B19306_01/server.102/b14211/optimops.htm#i52044
  
  and everything on the net.
  
  Edited by: jgarry 26 January 2011 17:41
  2nd edition: link fix that edit may 1 have ransacked.
  
  Edited by: jgarry January 27, 2011 10:40

  Joel,

  I just had this 'already seen' (new) sense to speak of it.

  Mentioning the reference 11.1 gave you:
  

  
  + "Index full scans are an alternative to a full table scan when the index contains all the columns needed for the query, and at least in the index key column has the constraint NOT NULL. A full scan can access the data of the index itself, without access to the table ' + '.
  

  This so obviously must be bad that I couldn't decide if I was proven wrong or was amazed to find that I couldn't he show the falsity. (Just because something is obvious, it does not mean it is true – Terry Pratchett.)

  However, here is the obvious counter-example - that I came across 8.1.7.4 because it's the oldest version of Oracle that I have now:

  create table t1
  as
  select
       rownum               id1,
       rownum               id2,
       rownum               id3,
       lpad(rownum,10,'0')     small_vc,
       rpad('x',100)          padding
  from
       all_objects
  where
       rownum <= 10000
  ;
  
  create index t1_i1 on t1(id1, id2, id3);
  
  begin
       dbms_stats.gather_table_stats(
            ownname           => user,
            tabname           =>'T1',
            cascade           => true
  
       );
  end;
  /
  
  set autotrace traceonly explain
  
  select
       /*+ index_ffs(t1) */
       id1, id3
  from
       t1
  where
       id2 = 99
  ;
  

  No 'NOT NULL columns". But any line I will have a (non-null) value for id2, then it should be in the index - then Oracle should be able to do a full scan and get the right answer. Here is the map (I have no need of Council - but your configuration may be different):

  Execution Plan
  ----------------------------------------------------------
     0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=4 Card=1 Bytes=12)
     1    0   INDEX (FAST FULL SCAN) OF 'T1_I1' (NON-UNIQUE) (Cost=4 Card=1 Bytes=12)
  

  If you change the predicate to: "id2 is zero", then the only legal path is an analysis.

  Concerning
  Jonathan Lewis
  http://jonathanlewis.WordPress.com
  http://www.jlcomp.demon.co.UK

  + "I believe in the evidence. I believe in observation, measurement and reasoning, confirmed by independent observers. I'll believe anything, no matter how wild and ridiculous, if there is evidence for it. The wildest and most ridiculous something is, however, the firmer and more solid, the evidence should be. » +
  Isaac Asimov

• How to index the condition 'null' or 'not null '?

  Hello together,
  
  first of all for your background, we would like to make the following changes to a Table:
  
  1. we have an old varchar2 (50) column that is filled with strings.
  2. we now have a new number (3) column that is blank.
  
  Our goal is to move from the old column a new column so that each different string is mapped to a number. ('abc' - > 0, "xyz"-> 1, etc.)
  The table that contains the columns has 1.3 billion lines. There is no index on the old column.
  
  If possible the migration should be made online (without interruption) and the temporary additional space should be as low as possible. Due to the effect of the performance, we plan to cut migration into several parts which will run on low load times.
  
  To avoid full table scans, I question whether it is possible to index the status of the line. With the status, I'm only interested in "null" or "not null".
  Is it possible to define a type of bitmap index? (0 = null, 1 = not null) which should stimulate the migration time and does not use the amount of memory?
  
  Unfortunately I am quite familiar with index now.
  
  
  To crack the migration in parts, I thought to use to use ' where rowum > = x and rownum < = x + 10, 000, 000and new_column is not null "to do it in steps 10mio.»
  
  Thanks in advance,
  Andreas

  Like this?

  CREATE INDEX idx_test
    ON TABLE_NAME (NVL2 (column_name, 0, 1));               -- NVL2--> if column is null then 0 else 1
  
  SELECT *
    FROM table_name
   WHERE NVL2 (column_name, 1, 0) = 1;
  

  G.

• Indexing options and search for Windows 7 are not locate content of the document since "update" Open Office 3.3 3.4 (he worked for 2 years before that)?

  I have Win 7 with Service Pack 1. I have "updated my Open Office 3.3 to 3.4 and now Win 7 search and options DO NOT locate my document content indexing more? I contacted the support of Open Office: http://user.services.openoffice.org/en/forum/viewtopic.php?f=15&t=55483

  They claim that: "indexing and search in Windows 7 are performed by Windows 7", so there is a problem with Win 7 search and indexing options.

  I checked the indexing options in Windows 7 and the "Index Properties and content of the file" is selected for ALL the 'odt' as well as all the files 'o'.

  I set up a test document: I put only one word "Wednesday" in the Open Office text document, saved and it called "text". I am looking for Wednesday and the search comes up with two other documents containing the word Wednesday in them, but not the Test document?

  I just discovered something. When I did the 'Test' experience above, the file was saved in format 'odt' a:. I changed it to a ".doc" file and it now appears in the search results. As mentioned above, I've changed ALL the files starting with the letter 'o' in Indexing Options > Advanced Options > Types of files to the article: 'properties Index and contents of the file. The description of filter for files 'odt' comes back as: "IFilter shop OpenOffice IFilter" where as 'doc' filter is listed as a: «Filter Microsoft Office» Is it a "Boutique OpenOffice IFilter IFilter: issue" Blocking "the documents appear in the search results? If so, how should I do (I mean in addition to all the documents 'odt' replacing 'doc'?

  Just to clarify: document names 'odt' come to a search, but not the content document.

  Hello

   

   

  Method 1: Run the following fix - it:

  Difficulty of Windows Desktop Search when it crashes or not display results:

  http://support.Microsoft.com/mats/windows_search/en-us

  Method 2:  Restore the computer to a date when it was working fine before:

  Reference:

  System Restore: frequently asked questions:

  http://Windows.Microsoft.com/en-us/Windows7/system-restore-frequently-asked-questions

• Purpose of "null is not null" and "null is null" statements

  Hi all

  Please can someone explain the purpose of these statements and what it means.

  1 null is not null

  2 null is null

  (a) NULL should be treated in a special way in the comparisons - see values NULL SQL - IS NULL and IS NOT NULL or SQL ISNULL(), NVL(), IFNULL() and COALESCE() functions

  (b) If you really clauses Null is not null or Null is null (meaning: the first is not a variable) it could replace "always wrong" and "always true"; Maybe in some test queries

• What index to use for 'where the pass is IS NOT NULL' query

  If I need a query of the form:

  Select * from INV_TABLE where R_TIMEOUT IS NOT NULL

  What type of index on the column R_TIMEOUT do you offer?

  Note that I'm only interested in the question of whether it is null or not.

  Thank you.

  It would really depend on how many lines was nothing compared to the number of lines not null.  An index of single column on r_timeout would be index only the non-null values, then, if most of the rows have a null value for r_timeout which could be quite effective as a path.  However, if most of the lines are not zero, then it is likely that a full table scan would be more effective, especially if you select all the columns in the table.

  John