Question

Is this a bug or a new behaviour?

Asked by: paquicuba

Can someone please try the SQLs below in 9i?

I tried in 8i, different 10g boxes and 11g...

The blank-padded comparison semantics works with outer joins in 8i, but it doesn't work in 10g or 11g  --a bug?


SQL> SELECT * FROM V$VERSION;

BANNER
----------------------------------------------------------------
Oracle8i Enterprise Edition Release 8.1.7.4.0 - 64bit Production
PL/SQL Release 8.1.7.4.0 - Production
CORE 8.1.7.0.0 Production
TNS for Solaris: Version 8.1.7.4.0 - Production
NLSRTL Version 3.4.1.0.0 - Production

Elapsed: 00:00:00.00
SQL> SELECT 'X' COL FROM DUAL WHERE 'X' = 'X '
2 /

C
-
X

Elapsed: 00:00:00.00
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X, (SELECT 'X ' COL FROM DUAL) Y
3 WHERE X.COL = Y.COL
4 /

C COL
- ----
X X

Elapsed: 00:00:00.00
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X, (SELECT 'X ' COL FROM DUAL) Y
3 WHERE X.COL = Y.COL(+)
4 /

C COL
- ----
X X

Elapsed: 00:00:00.00
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X, (SELECT 'X ' COL FROM DUAL) Y
3 WHERE X.COL(+) = Y.COL
4 /

C COL
- ----
X X

Elapsed: 00:00:00.00





SQL> SELECT * FROM V$VERSION;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE 10.2.0.4.0 Production
TNS for Solaris: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production

Elapsed: 00:00:00.25
SQL> SELECT 'X' COL FROM DUAL WHERE 'X' = 'X '
2 /

C
-
X

Elapsed: 00:00:00.01
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X, (SELECT 'X ' COL FROM DUAL) Y
3 WHERE X.COL = Y.COL
4 /

C COL
- ----
X X

Elapsed: 00:00:00.03
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X, (SELECT 'X ' COL FROM DUAL) Y
3 WHERE X.COL = Y.COL(+)
4 /

C COL
- ----
X

Elapsed: 00:00:00.03
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X, (SELECT 'X ' COL FROM DUAL) Y
3 WHERE X.COL(+) = Y.COL
4 /

C COL
- ----
X

Elapsed: 00:00:00.03
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X LEFT OUTER JOIN (SELECT 'X ' COL FROM DUAL) Y
3 ON(X.COL = Y.COL)
4 /

C COL
- ----
X

Elapsed: 00:00:00.03
SQL>

Thanks a lot!

Alex

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Asked On
2008-11-06 at 13:36:13ID23883416
Tags

Oracle

,

Oracle database

,

10g

,

Bug?

Topics

Oracle Database

,

Oracle 10.x

Participating Experts
3
Points
500
Comments
13

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Answers

 

by: anand_2000vPosted on 2008-11-06 at 22:23:05ID: 22902232

can you try
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X left outer join (SELECT 'X ' COL FROM DUAL) Y
3 /


and

SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X right outer join (SELECT 'X ' COL FROM DUAL) Y
3 /

 

by: anand_2000vPosted on 2008-11-06 at 22:24:12ID: 22902234

sorry
can you try
SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X left outer join (SELECT 'X ' COL FROM DUAL) Y
3 on (x.col=y.col)
4 /


and

SQL> SELECT X.COL, Y.COL FROM
2 (SELECT 'X' COL FROM DUAL) X right outer join (SELECT 'X ' COL FROM DUAL) Y
3 on (x.col=y.col)
4 /

 

by: paquicubaPosted on 2008-11-07 at 06:19:21ID: 22904470

Thanks anand!

I already tried that syntax as you can see it in my last query posted. Anyway, it's still not backward compatible with 8i...

  1  SELECT X.COL, Y.COL FROM
  2  (SELECT 'X' COL FROM DUAL) X left outer join (SELECT 'X ' COL FROM DUAL) Y
  3* on (x.col=y.col)
  4  /

C CO
- --
X

Elapsed: 00:00:00.14
OVNDW@p014> edit
Wrote file afiedt.buf

  1  SELECT X.COL, Y.COL FROM
  2  (SELECT 'X' COL FROM DUAL) X right outer join (SELECT 'X ' COL FROM DUAL) Y
  3* on (x.col=y.col)
OVNDW@p014> /

C CO
- --
  X

 

by: anand_2000vPosted on 2008-11-07 at 07:39:43ID: 22905330

sorry...did not notice that earlier,

I also tested it out, on various platforms/Sun/HP/Windoze/Linux

It is consistent throughout...

Seems to be a feature, though it is not mentioned in anyplace that I have looked. Nothing in Metalink either about this.

 

by: paquicubaPosted on 2008-11-07 at 09:16:31ID: 22906487

I found this behaviour while debugging a query that was working in 8i and stopped working in 10g.

A table involved in the query has a CHAR datatype column where its values don't always fill all the spaces (bytes), so: when length(non-null value) <  "fixed column length"  then "pad with blank spaces"

Eg.  
Column "Country  CHAR(3)" may contain value 'USA' or 'US'
When you query the table using an equi-join, although the length is 3 bytes, Oracle implicitly trims blank-spaces in all versions.
However, in 8i Oracle also implicitly trims blank-spaces for outer-joins, but it doesn't implicitly trim blank-spaces for any version released after 8i.

The quick fix is to trim CHAR columns involved in the outer-join, but now I have to look into thousand of queries to see if any of them could have been affected by this change on behaviour or --> bug?

Thanks!

 

by: awking00Posted on 2008-11-07 at 10:52:53ID: 22907394

See comments attached.

 

by: awking00Posted on 2008-11-07 at 10:54:54ID: 22907418

Sorry, I guess that was the whole point of the question. DOH!

 

by: paquicubaPosted on 2008-11-07 at 11:04:14ID: 22907502

You're right, that's the point...

Don't you agree that this change in behaviour is a dangerous thing, since instead of an error you're simply getting wrong results?

 

by: awking00Posted on 2008-11-07 at 11:44:19ID: 22907846

I think it's downright scary.

 

by: anand_2000vPosted on 2008-11-07 at 13:19:33ID: 22908625

maybe someone from Oracle might answer. I will try to raise a SR in Metalink...

 

by: sujith80Posted on 2008-11-07 at 17:49:05ID: 22910053

Looks like an issue with implicit type conversion behaviour.

>> When you query the table using an equi-join, although the length is 3 bytes
But if you are doing an equi-join between a CHAR(n) column with another CHAR(n) column, then it shouldn't be a problem right? because if it trims or not the data is essentially the same.
Say if the data doesnt fill the length of the column, then it is going to be blank padded to the column width in both tables. The behaviour may be different if the column width are different in both tables.

SQL> desc tbl1;
 Name                                            Null?    Type
 ----------------------------------------------- -------- --------------------------------
 COL                                                      CHAR(3)
 
SQL> select replace(col, ' ', '*') from tbl1;
 
REP
---
X**
 
SQL> SELECT replace(X.COL,' ','*') , replace(Y.COL, ' ','*') FROM
  2  (SELECT COL FROM TBL1) X, (SELECT 'X' COL FROM DUAL) Y
  3  WHERE X.COL = Y.COL;
 
REP R
--- -
X** X
 
SQL> SELECT replace(X.COL,' ','*') , replace(Y.COL, ' ','*') FROM
  2  (SELECT COL FROM TBL1) X LEFT OUTER JOIN (SELECT 'X' COL FROM DUAL) Y
  3  ON(X.COL = Y.COL);
 
REP R
--- -
X**
 
SQL> SELECT replace(X.COL,' ','*') , replace(Y.COL, ' ','*') FROM
  2  (SELECT COL FROM TBL1) X LEFT OUTER JOIN (SELECT cast('X' as char(3))  COL FROM DUAL) Y
  3  ON(X.COL = Y.COL);
 
REP REP
--- ---
X** X**
 
SQL> 

                                              
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by: paquicubaPosted on 2008-11-08 at 09:03:09ID: 31514137

Thanks a bunch gang for your answers!
I also posted the same question in the Oracle's website's forum...

 

by: sujith80Posted on 2008-11-13 at 22:14:49ID: 22957569

Alex,
Keep us posted on any updates on this issue.

20120131-EE-VQP-002

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