LI75692: A RANGE JOIN PREDICATE JOINED TO A UNION ALL VIEW WITH A GROUP B Y CLAUSE MAY PRODUCE A SUB-OPTIMAL PLAN.

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Error description

• ```Db2 may not push down a range join to a Union All view into the
tables of the Union All view.This would prevent Db2 to produce
a sub-optimal plan.
.
The following conditions must be met in order to hit this proble
m:
.
1)  There is a Group By clause on the table and the Union
All view of the range join predicate.
2)  Any column from the table in the range join predicate
derives from an expression that is not a column.
.
For example:
.
create table br1(tranid integer, trandate date, amount decimal);
create table br2(tranid integer, trandate date, amount decimal);
create view ua as (select * from br1 union all select * from
br2);
.
create table datedim(durid integer, startdate date, enddate
date);
.
create view vdatedim(durid, startdate, enddate)
as
(select  durid,
case when month(startdate) = 3 then startdate + 1 day
else startdate end startdate,
enddate
from     datedim
);
.
select ua.trandate, count(tranid), sum(amount)
from    ua, vdatedim
where  ua.trandate between vdatedim.startdate and
vdatedim.enddate
group by ua.trandate
;
.
```

Problem summary

• ```Db2 may not push down a range join to a Union All view into the
tables of the Union All view.This would prevent Db2 to produce
a sub-optimal plan.
.
The following conditions must be met in order to hit this proble
m:
.
1)  There is a Group By clause on the table and the Union
All view of the range join predicate.
2)  Any column from the table in the range join predicate
derives from an expression that is not a column.
.
For example:
.
create table br1(tranid integer, trandate date, amount decimal);
create table br2(tranid integer, trandate date, amount decimal);
create view ua as (select * from br1 union all select * from
br2);
.
create table datedim(durid integer, startdate date, enddate
date);
.
create view vdatedim(durid, startdate, enddate)
as
(select  durid,
case when month(startdate) = 3 then startdate + 1 day
else startdate end startdate,
enddate
from     datedim
);
.
select ua.trandate, count(tranid), sum(amount)
from    ua, vdatedim
where  ua.trandate between vdatedim.startdate and
vdatedim.enddate
group by ua.trandate

;
```

Problem conclusion

• ```apar li75692
fixed >= v95 fpk7
```

APAR Information

LI75692

• Reported component name

DB2 UDE ESE LIN

5765F4104

950

CLOSED PER

NoPE

NoHIPER

NoSpecatt

2010-09-02

2010-12-20

2010-12-20

Modules/Macros

• ```ENG_SQNR
```

Fix information

• Fixed component name

DB2 UDE ESE LIN

5765F4104

Applicable component levels

• R950 PSN

UP

[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSEPGG","label":"DB2 for Linux, UNIX and Windows"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"950","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Modified date:
20 December 2010