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From "Craig Russell (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3301) Incorrect result from query with nested EXIST
Date Sun, 20 Jan 2008 23:44:34 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12560902#action_12560902
] 

Craig Russell commented on DERBY-3301:
--------------------------------------

> Too late to keep working - EXIST should return only one row.
There are many ways to evaluate the query, depending on the strategy. Yes, each of the EXISTS
clauses should return either zero or one row, depending on whether the EXISTS condition is
true for the specific row of the outermost FROM clause.

For each row of the outer product of the outermost FROM clause (DEPARTMENTS, EMPLOYEES, PROJECTS),
the middle WHERE EXISTS should return true when there is a match between the EMPLOYEES and
PROJECTS in the join table. As an optimization, you could invert the scan and look at all
of the rows of the join table. It's hard to tell from the analysis here whether Derby is inverting
the scan.

> Incorrect result from query with nested EXIST
> ---------------------------------------------
>
>                 Key: DERBY-3301
>                 URL: https://issues.apache.org/jira/browse/DERBY-3301
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.1.3.1, 10.2.1.6, 10.3.2.1
>            Reporter: Craig Russell
>         Attachments: d3301-queryplan.log, derby-3301.sql
>
>
> Derby returns unexpected results from a query with embedded EXIST clauses. The query
SQL is generated by the JPOX jdo implementation and is supposed to return all of the PERSONS
and PROJECTS where there is an entry in the join table. This query works as expected when
using MySQL.
> Here's the query:
> SELECT UNBOUND_E.PERSONID, UNBOUND_P.PROJID 
> FROM applicationidentity0.DEPARTMENTS THIS, 
>      applicationidentity0.PERSONS UNBOUND_E, 
>      applicationidentity0.PROJECTS UNBOUND_P 
> WHERE EXISTS ( 
>     SELECT 1 FROM applicationidentity0.PERSONS THIS_EMPLOYEES_E 
>     WHERE EXISTS ( 
>         SELECT 1 FROM applicationidentity0.PROJECT_MEMBER THIS_EMPLOYEES_E_PROJECTS_P

>         WHERE THIS_EMPLOYEES_E_PROJECTS_P."MEMBER" = THIS_EMPLOYEES_E.PERSONID 
>         AND THIS_EMPLOYEES_E_PROJECTS_P."MEMBER" = THIS_EMPLOYEES_E.PERSONID 
>         AND THIS_EMPLOYEES_E.DEPARTMENT = THIS.ID 
>         AND THIS_EMPLOYEES_E.DEPARTMENT = THIS.ID 
>         AND UNBOUND_P.PROJID = THIS_EMPLOYEES_E_PROJECTS_P.PROJID 
>         AND UNBOUND_E.PERSONID = THIS_EMPLOYEES_E.PERSONID) 
>     );
> PERSONID   |PROJID     
> -----------------------
> 3          |1          
> 5          |3          
> 4          |3          
> 2          |1          
> 1          |1          
> 5 rows selected
> I'm expecting 7 rows to be returned here, one row for each row in the join table. 
> Here's the schema:
> CREATE TABLE departments (
>     ID INTEGER NOT NULL,
>     NAME VARCHAR(32) NOT NULL,
>     EMP_OF_THE_MONTH INTEGER,
>     COMPANYID INTEGER,
>     DISCRIMINATOR VARCHAR(255),
>     CONSTRAINT DEPTS_COMP_FK FOREIGN KEY (COMPANYID) REFERENCES companies,
>     CONSTRAINT DEPTS_PK PRIMARY KEY (ID)
> );
> CREATE TABLE persons (
>     PERSONID INTEGER NOT NULL,
>     FIRSTNAME VARCHAR(32) NOT NULL,
>     LASTNAME VARCHAR(32) NOT NULL,
>     MIDDLENAME VARCHAR(32),
>     BIRTHDATE TIMESTAMP NOT NULL,
>     ADDRID INTEGER,
>     STREET VARCHAR(64),
>     CITY VARCHAR(64),
>     STATE CHAR(2),
>     ZIPCODE CHAR(5),
>     COUNTRY VARCHAR(64),
>     HIREDATE TIMESTAMP,
>     WEEKLYHOURS REAL,
>     DEPARTMENT INTEGER,
>     FUNDINGDEPT INTEGER,
>     MANAGER INTEGER,
>     MENTOR INTEGER,
>     HRADVISOR INTEGER,
>     SALARY REAL,
>     WAGE REAL,
>     DISCRIMINATOR varchar(255) NOT NULL,
>     CONSTRAINT PERS_DEPT_FK FOREIGN KEY (DEPARTMENT) REFERENCES departments,
>     CONSTRAINT PERS_FUNDDEPT_FK FOREIGN KEY (FUNDINGDEPT) REFERENCES departments,
>     CONSTRAINT PERS_MANAGER_FK FOREIGN KEY (MANAGER) REFERENCES persons,
>     CONSTRAINT PERS_MENTOR_FK FOREIGN KEY (MENTOR) REFERENCES persons,
>     CONSTRAINT PERS_HRADVISOR_FK FOREIGN KEY (HRADVISOR) REFERENCES persons,
>     CONSTRAINT EMPS_PK PRIMARY KEY (PERSONID)
> );
> CREATE TABLE projects (
>     PROJID INTEGER NOT NULL,
>     NAME VARCHAR(32) NOT NULL,
>     BUDGET DECIMAL(11,2) NOT NULL,
>     DISCRIMINATOR VARCHAR(255),
>     CONSTRAINT PROJS_PK PRIMARY KEY (PROJID)
> );
> CREATE TABLE project_member (
>     PROJID INTEGER REFERENCES projects NOT NULL,
>     MEMBER INTEGER REFERENCES persons NOT NULL
> );
> ij> connect 'jdbc:derby:/Users/clr/apache/jdo/trunk/tck2/target/database/derby/jdotckdb';
> ij> set schema applicationidentity0;
> 0 rows inserted/updated/deleted
> ij> select * from persons;
> PERSONID   |FIRSTNAME                       |LASTNAME                        |MIDDLENAME
                     |BIRTHDATE                 |ADDRID     |STREET                      
                                   |CITY                                                 
          |STA&|ZIPC&|COUNTRY                                                    
    |HIREDATE                  |WEEKLYHOURS  |DEPARTMENT |FUNDINGDEPT|MANAGER    |MENTOR 
   |HRADVISOR  |SALARY       |WAGE         |DISCRIMINATOR                                
                                                                                  
> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> 1          |emp1First                       |emp1Last                        |emp1Middle
                     |1970-06-09 21:00:00.0     |NULL       |NULL                        
                                   |NULL                                                 
          |NULL|NULL |NULL                                                            |1998-12-31
21:00:00.0     |40.0         |NULL       |NULL       |NULL       |NULL       |NULL       |20000.0
     |NULL         |org.apache.jdo.tck.pc.company.FullTimeEmployee                       
                                                          
> 2          |emp2First                       |emp2Last                        |emp2Middle
                     |1975-12-21 21:00:00.0     |NULL       |NULL                        
                                   |NULL                                                 
          |NULL|NULL |NULL                                                            |2003-06-30
21:00:00.0     |40.0         |NULL       |NULL       |NULL       |NULL       |NULL       |10000.0
     |NULL         |org.apache.jdo.tck.pc.company.FullTimeEmployee                       
                                                          
> 3          |emp3First                       |emp3Last                        |emp3Middle
                     |1972-09-04 21:00:00.0     |NULL       |NULL                        
                                   |NULL                                                 
          |NULL|NULL |NULL                                                            |2002-08-14
21:00:00.0     |19.0         |NULL       |NULL       |NULL       |NULL       |NULL       |NULL
        |15.0         |org.apache.jdo.tck.pc.company.PartTimeEmployee                    
                                                             
> 4          |emp4First                       |emp4Last                        |emp4Middle
                     |1973-09-05 21:00:00.0     |NULL       |NULL                        
                                   |NULL                                                 
          |NULL|NULL |NULL                                                            |2001-04-14
21:00:00.0     |0.0          |NULL       |NULL       |NULL       |NULL       |NULL       |NULL
        |13.0         |org.apache.jdo.tck.pc.company.PartTimeEmployee                    
                                                             
> 5          |emp5First                       |emp5Last                        |emp5Middle
                     |1962-07-04 21:00:00.0     |NULL       |NULL                        
                                   |NULL                                                 
          |NULL|NULL |NULL                                                            |1998-08-14
21:00:00.0     |0.0          |NULL       |NULL       |NULL       |NULL       |NULL       |45000.0
     |NULL         |org.apache.jdo.tck.pc.company.FullTimeEmployee                       
                                                          
> 5 rows selected
> ij> select * from projects;
> PROJID     |NAME                            |BUDGET       |DISCRIMINATOR            
                                                                                         
            
> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> 1          |orange                          |2500000.99   |org.apache.jdo.tck.pc.company.Project
                                                                                         

> 2          |blue                            |50000.00     |org.apache.jdo.tck.pc.company.Project
                                                                                         

> 3          |green                           |2000.99      |org.apache.jdo.tck.pc.company.Project
                                                                                         

> 3 rows selected
> ij> select * from project_member;
> PROJID     |MEMBER     
> -----------------------
> 2          |3          
> 1          |3          
> 2          |2          
> 3          |5          
> 3          |4          
> 1          |2          
> 1          |1          
> 7 rows selected

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