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https://issues.apache.org/jira/browse/DERBY-3301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12562427#action_12562427
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Thomas Nielsen commented on DERBY-3301:
---------------------------------------
Thanks for the input Army.
Ad 1)
I agree, the 3b comments miss the point slightly, and may be seen as 'inverted'.
>
> I think that if SQ1 *is* a nested WHERE EXISTS subquery in the WHERE EXISTS
> clause of SQ2, then it's technically _SQ2_ that is not flattenable, not SQ1.
>
This is correct, to my understanding. Your comment suggestion is a lot better,
even if it is more elaborate.
Ad 2)
True, 3b only takes the actual problem reported into consideration.
I reread the last bullet on the flattening criteria list
(http://db.apache.org/derby/docs/10.3/tuning/ctuntransform25868.html) again.
You are once again correct Army.
If SQ2 a has *any* subquery SQ1 in its WHERE EXISTS clause, flattening of SQ2
should be skipped. Not flattening in the case where SQ2 is an ANY or IN query
is already handled in the existing code.
I'll look into CollectNodesVisitor and post an updated patch.
> 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
> Assignee: Thomas Nielsen
> Attachments: d3301-queryplan.log, derby-3301-1.diff,
> derby-3301-1.stat, derby-3301-2.diff, derby-3301-3.diff, derby-3301-3b.diff,
> derby-3301-test-1.diff, derby-3301-test-1.stat, 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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