Alternate to group by clause

Hi
I am using Oracle 8i and one of my queries is getting the data from multiple sources through a dblink from other databases (customer need cannot avoid dblinks).
The query is using the group by clause to get the count based on specific columns and when i am not using the group by the query is pretty fast.
select count(id), col1,col2,col3
from source1@dblink1,
source2@dblink1,
source3@dblink1,
source4@dblink1,
source5@dblink1
where
group by col1,col2,col3
Please suggest the use of other Oracle features that we can use (pl/sql table or looping in pl/sql instead of using group by ) as the amount of data is large and it has to go through several iterations and accordingly update my local db with the counts returned.
An example will be quite helpful.
Thanks in Advance.

Hi,
i have a procedure that has a cursor thats using db links as above, in the code if i open the cursor and say NULL even then it is taking about 8 mins while the cursor query is taking about 2 mins only when run separately.
i open the cursor
for c1 in cursor loop
NULL;
end loop;
it hangs on for about 8 mins , while if i run the query of the cursor with the same parameters that i pass in the cursor at run time it takes about 2 mins.
Dont understand where the 6 mins are going.
If the cursor is not opened at all in the proc it gets executed in less than a second so there is no other code thats consuming time.
Please suggest.

Similar Messages

How to include case stmt in group by clause

Hi i have a question,
How do i include a case statement in the group by clause?
For example:
Select
(case when x.ctry is null then y.ctry else x.ctry end) as coo,
sum (x.in_amt)
from
tbl1 x,
tbl2 y
where
x.id = y.id
group by
(case when x.ctry is null then y.ctry else x.ctry end)
Assume, I have got millions of records in both the tables, then my guess is, the above query might take huge time to complete.
Any alternate method to do this?

cd/ wrote:
To remove the expression from the GROUP BY clause. I didn't advocate any performance improvements, did I?No you didn't. And your advice can indeed remove the expression from the GROUP BY clause. But I'm still puzzled as to why that would be a goal in itself.
Regards,
Rob.

Default Sorting behaviour of Oracle 9i in 11g along with group by clause

Hi,
We have recently migrated from 9i to 11g. The reports from application comes in a jumbled fashion. Later we understood when there is a group by clause in the query, the recordset will be sorted by default in 9i and this feature is not available in 11g. Do anyone faced the same issue and resolved at the DB level.
Only alternate we found is the change in code with addittional order by clause which will take a long time to complete and roll out the same.
If anyone has got any immediate solution, please let me know.
Thx in advance.
Sheen

Hi,
A group by can sort (depending on the method of grouping) but it isn't necessary. If you want to sort the output you need the ORDER BY clause. There are different group by mechanismes between 9i and 11g. 10g introduced HASH GROUP BY where in 9i only the SORT GROUP BY existed. The latter gives a sorted set, the first not.
if you want the same behaviour you can use "_gby_hash_aggregation_enabled parameter" = false, which disables the hash group by.
Have also a look at the support document "'Group By' Does Not Guarantee a Sort Without Order By Clause In 10g and Above [ID 345048.1]".
Herald ten Dam
http://htendam.wordpress.com

Why is the GROUP BY clause not working in my Query?

Dear All,
Below is the Query for a Summary Debtors Aged Analysis.
The GROUP BY clause does not seem to be working.
The Query returns all the unpaid invoices, instead of a single total row for each Customer.
If a Customer X has 10 unpaid invoices, 10 rows are displayed - one for each invoice.
I was expecting only 1 row for Customer X, 1 for Customer Y, etc.
This is what GROUP BY is supposed to do, but it is not doing its work.
What has gone wrong?
Thanks
Leon Lai
Here's my Query:
declare @taxdt datetime
set @taxdt
/*select 1 from jdt1 t0 where t0.TaxDate*/ = [%1]
SELECT
CASE
             WHEN T0.Account = 1220101 THEN 'Prim Cust'
             WHEN T0.Account = 1220102 THEN 'Fgn Cust'
             WHEN T0.Account = 1220103 THEN 'Local Cust'
             WHEN T0.Account = 1220104 THEN 'Staff Loan'
             WHEN T0.Account = 1220105 THEN 'Dep with TP'
             WHEN T0.Account = 1220106 THEN 'Adv to Cust'
             WHEN T0.Account = 1220108 THEN 'Sund Drs'
             ELSE 'Error ! ! !'
END AS 'Control A/c',
T1.CardCode AS 'BP Code',
T2.Notes2 AS 'BP Name',
SUM ((T0.Debit - T0.Credit)) AS 'Orig. Rs',
SUM ((T0.BalDueDeb - T0.BalDueCred)) AS 'Bal. Rs',
((SELECT SUM(T0.BalDueDeb) - Sum(T0.BalDueCred)
    WHERE DateDiff(mm, T0.TaxDate, @taxdt) = 1))
    AS '1 Mth Ago'
/* Similarly for other age brackets*/
FROM JDT1 T0
INNER JOIN OCRD T1 ON T0.ShortName = T1.CardCode
LEFT OUTER JOIN OCPR T2 ON T1.CardCode = T2.Cardcode
LEFT OUTER JOIN OJDT T3 ON T0.TransID = T3.TransID
LEFT OUTER JOIN OINV T4 ON T3.TransID = T4.TransID
LEFT OUTER JOIN ORIN T5 ON T3.TransID = T5.TransID
WHERE
T1.CardType = 'C'
and (Balance) != 0
and (T0.BalDueDeb - T0.BalDueCred) != 0
GROUP BY T0.Account, T1.CardCode, T2.Notes2, T0.TaxDate

Dear Neetu,
Thanks for your reply.
This Query is a modification of the Query you posted in SAP B1 SQL TIPS & TRICKS
http://wiki.sdn.sap.com/wiki/display/B1/SAPB1SQLB-FNDebtorsAgingReportbydate
So, maybe instead of referring to my Query, let's refer to yours. It may be easier for you to understand me.
Once I understand the problem, I can adapt your query to suit my requirements
So, let's start with a clean slate:
The Query you have posted is for a DETAILED Debtors Aging Report.
This lists all outstanding invoices, and ages them in the Age Brackets.
What I want is a SUMMARY Debtors Aging Report.
This will give the total amount owed by each Customer, and this amount is broken down in the Age Bracket Columns
There will be a single row listed for each customer, something like this:
Customer     Total Due     Current      1 Mth          2 Mth         3 Mth etc
Alfred       500,000       300,000       200,000
Charles      800,000                     100,000       300,000       400,000
How can you modify your query to make it become a Summary Report (1 line for each customer even if he has many invoices)?
Thanks
Leon Lai
Here's your code
SELECT T1.CardCode, T1.CardName, T1.CreditLine, T0.RefDate, T0.Ref1 'Document Number',
     CASE WHEN T0.TransType=13 THEN 'Invoice'
          WHEN T0.TransType=14 THEN 'Credit Note'
          WHEN T0.TransType=30 THEN 'Journal'
          WHEN T0.TransType=24 THEN 'Receipt'
          END AS 'Document Type',
     T0.DueDate, (T0.Debit- T0.Credit) 'Balance'
     ,ISNULL((SELECT T0.Debit-T0.Credit WHERE DateDiff(day, T0.DueDate,'[%1]')<=-1),0) 'Future'
     ,ISNULL((SELECT T0.Debit-T0.Credit WHERE DateDiff(day, T0.DueDate,'[%1]')>=0 and DateDiff(day, T0.DueDate,'[%1]')<=30),0) 'Current'
     ,ISNULL((SELECT T0.Debit-T0.Credit WHERE DateDiff(day, T0.DueDate,'[%1]')>30 and DateDiff(day, T0.DueDate,'[%1]')<=60),0) '31-60 Days'
     ,ISNULL((SELECT T0.Debit-T0.Credit WHERE DateDiff(day, T0.DueDate,'[%1]')>60 and DateDiff(day, T0.DueDate,'[%1]')<=90),0) '61-90 Days'
     ,ISNULL((SELECT T0.Debit-T0.Credit WHERE DateDiff(day, T0.DueDate,'[%1]')>90 and DateDiff(day, T0.DueDate,'[%1]')<=120),0) '91-120 Days'
     ,ISNULL((SELECT T0.Debit-T0.Credit WHERE DateDiff(day, T0.DueDate,'[%1]')>=121),0) '121+ Days'
FROM JDT1 T0 INNER JOIN OCRD T1 ON T0.ShortName = T1.CardCode
WHERE (T0.MthDate IS NULL OR T0.MthDate > [%1]) AND T0.RefDate <= [%1] AND T1.CardType = 'C'
ORDER BY T1.CardCode, T0.DueDate, T0.Ref1

How to write a SQL Query without using group by clause

Hi,
Can anyone help me to find out if there is a approach to build a SQL Query without using group by clause.
Please site an example if is it so,
Regards

I hope this example could illuminate danepc on is problem.
CREATE or replace TYPE MY_ARRAY AS TABLE OF INTEGER
CREATE OR REPLACE FUNCTION GET_ARR return my_array
as
     arr my_array;
begin
     arr := my_array();
     for i in 1..10 loop
          arr.extend;
          arr(i) := i mod 7;
     end loop;
     return arr;
end;
select column_value
from table(get_arr)
order by column_value;
select column_value,count(*) occurences
from table(get_arr)
group by column_value
order by column_value;And the output should be something like this:
SQL> CREATE or replace TYPE MY_ARRAY AS TABLE OF INTEGER
2 /
Tipo creato.
SQL>
SQL> CREATE OR REPLACE FUNCTION GET_ARR return my_array
2 as
3   arr my_array;
4 begin
5   arr := my_array();
6   for i in 1..10 loop
7    arr.extend;
8    arr(i) := i mod 7;
9   end loop;
10   return arr;
11 end;
12 /
Funzione creata.
SQL>
SQL>
SQL> select column_value
2 from table(get_arr)
3 order by column_value;
COLUMN_VALUE
           0
           1
           1
           2
           2
           3
           3
           4
           5
           6
Selezionate 10 righe.
SQL>
SQL> select column_value,count(*) occurences
2 from table(get_arr)
3 group by column_value
4 order by column_value;
COLUMN_VALUE OCCURENCES
           0          1
           1          2
           2          2
           3          2
           4          1
           5          1
           6          1
Selezionate 7 righe.
SQL> Bye Alessandro

How to use order by within Group by clause

Hi All,
I need a help as to how should i use the Order by clause so that the data should be in order with respect to one column, and at the same time whole data is grouped by some other column...like
Select RaceNo,Venue,FP,BP from Race group by RaceNo
Here I want to order by FP in ascending order for each group. When i am using it , whole order is changing.
Can anybody suggest me how to use order by clause that would apply to each group of data.
Thanks .

order by clause should be used at the last in any query.......but in group by clause u can't use use that becoz u group according to column then no ordering is needed there......if u want to filter something then u can use having clause and later if u need to arrange then u can use order by clause.........
i hope this eg.l gives u some clarification....
e.g
select deptno,count(empno)
from dept
group by deptno
having count(empno) > 10
order by deptno

Creation of view with clob column in select and group by clause.

Hi,
We are trying to migrate a view from sql server2005 to oracle 10g. It has clob column which is used in group by clause. How can the same be achived in oracle 10g.
Below is the sql statament used in creating view aling with its datatypes.
CREATE OR REPLACE FORCE VIEW "TEST" ("CONTENT_ID", "TITLE", "KEYWORDS", "CONTENT", "ISPOPUP", "CREATED", "SEARCHSTARTDATE", "SEARCHENDDATE", "HITS", "TYPE", "CREATEDBY", "UPDATED", "ISDISPLAYED", "UPDATEDBY", "AVERAGERATING", "VOTES") AS
SELECT content_ec.content_id,
          content_ec.title,
          content_ec.keywords,
          content_ec.content content ,
          content_ec.ispopup,
          content_ec.created,
          content_ec.searchstartdate,
          content_ec.searchenddate,
        COUNT(contenttracker_ec.contenttracker_id) hits,
          contenttypes_ec.type,
          users_ec_1.username createdby,
          Backup_Latest.created updated,
          Backup_Latest.isdisplayed,
          users_ec_1.username updatedby,
          guideratings.averagerating,
          guideratings.votes
     FROM users_ec users_ec_1
            JOIN Backup_Latest
             ON users_ec_1.USER_ID = Backup_Latest.USER_ID
            RIGHT JOIN content_ec
            JOIN contenttypes_ec
             ON content_ec.contenttype_id = contenttypes_ec.contenttype_id
             ON Backup_Latest.content_id = content_ec.content_id
            LEFT JOIN guideratings
             ON content_ec.content_id = guideratings.content_id
            LEFT JOIN contenttracker_ec
             ON content_ec.content_id = contenttracker_ec.content_id
            LEFT JOIN users_ec users_ec_2
             ON content_ec.user_id = users_ec_2.USER_ID
     GROUP BY content_ec.content_id,
     content_ec.title,
     content_ec.keywords,
     to_char(content_ec.content) ,
     content_ec.ispopup,
     content_ec.created,
     content_ec.searchstartdate,
     content_ec.searchenddate,
     contenttypes_ec.type,
     users_ec_1.username,
     Backup_Latest.created,
     Backup_Latest.isdisplayed,
     users_ec_1.username,
     guideratings.averagerating,
     guideratings.votes;
Column Name      Data TYpe
CONTENT_ID     NUMBER(10,0)
TITLE          VARCHAR2(50)
KEYWORDS     VARCHAR2(100)
CONTENT          CLOB
ISPOPUP          NUMBER(1,0)
CREATED          TIMESTAMP(6)
SEARCHSTARTDATE     TIMESTAMP(6)
SEARCHENDDATE     TIMESTAMP(6)
HITS          NUMBER
TYPE          VARCHAR2(50)
CREATEDBY     VARCHAR2(20)
UPDATED          TIMESTAMP(6)
ISDISPLAYED     NUMBER(1,0)
UPDATEDBY     VARCHAR2(20)
AVERAGERATING     NUMBER
VOTES          NUMBERAny help realyy appreciated.
Thanks in advance
Edited by: user512743 on Dec 10, 2008 10:46 PM

Hello,
Specifically, this should be asked in the
ASP.Net MVC forum on forums.asp.net.
Karl
When you see answers and helpful posts, please click Vote As Helpful, Propose As Answer, and/or Mark As Answer.
My Blog: Unlock PowerShell
My Book: Windows PowerShell 2.0 Bible
My E-mail: -join ('6F6C646B61726C40686F746D61696C2E636F6D'-split'(?<=\G.{2})'|%{if($_){[char][int]"0x$_"}})

-- SQL -- GROUP BY clause: non-aggregate fields mandate

Hello,
I was studying Databases, (particularly the retrieval of the data), and found something interesting.
While using an Aggregate Function in the SELECT clause, it is mandatory to have all the non-aggregate fields in the SELECT clause to be there in the GROUP BY clause.
For example,
SELECT dept_no, SUM(salary)
FROM employee
GROUP BY dept_no;
The above SQL works fine.
But, what if the user misses the dept_no in the GROUP BY clause or he/she misses the GROUP BY clause itself?
Certainly, it is an error.
Why is this error not handled by the database. I mean, the database should be smart/intelligent enough to add the GROUP BY clause by itself. So suppose, if I miss out the GROUP BY clause or miss a non-aggregate field from the SELECT clause when I am having at least one aggregate function on a field with at least one non-aggregated field in the SELECT clause, the database should check the GROUP BY clause at time of compilation and add the mandate missed out fields in the GROUP BY clause.
Example,
SQL1:_
SELECT dept_no, SUM(salary)
FROM employee
GROUP BY dept_no;
SQL2:_
SELECT dept_no, SUM(salary)
FROM employee;
Here, the SQL1 and SQL2, both should give me same outputs without an error.
I am unable to understand why is this not handled?

Hi,
998478 wrote:
... If we mix aggregate and non-aggregate values then there must be a GROUP BY clause containing all the non-aggregate values. Why is this not handled by the database/compiler itself? It IS handled by the compiler itself. The compiler handles it by raising an error. The compiler has no way of knowing whether you want to remove something from the SELECT clause, or to add something to the GROUP BY clause, or not to use aggregate functions, or to use more aggregate functions, or some combination of the above. If the compiler re-wrote your code, and did any of these things automatically, it would be wrong more often than it was right, and you would (rightly) be complaining about its behavior.
For example, this is clearly wrong:
SELECT    deptno
,       job
,       SUM (sal)
FROM       scott.emp
GROUP BY deptno
;What is the right way to fix it?
<h3>1. Remove something from the SELECT clause</h3>
SELECT    deptno
,       SUM (sal)
FROM       scott.emp
GROUP BY deptno
;<h3>2. Add something to the GROUP BY clause</h3>
SELECT    deptno
,       job
,       SUM (sal)
FROM       scott.emp
GROUP BY deptno
,         job
;<h3>3. Not use aggregate functions</h3>
SELECT    deptno
,       job
,       sal
FROM       scott.emp
;<h3>4. Use more aggregate functions</h3>
SELECT    deptno
,       MIN (job)
,       SUM (sal)
FROM       scott.emp
GROUP BY deptno
;These aren't all the options, either. For example, the correct fix might be to use analytic functions instead of aggregate functions.
How can anybody say which of these is right? All of them are the right answer for some problem.
By the way, saying that everying in the SELECT clause must be an aggregate or in the GROUP BY clause is a bit over-simplified.
More completely, here are the ABC's of GROUP BY:
When you use a GROUP BY clause and/or an aggregate function, then everything in the SELECT clause must be:
(A) an <b>A</b>ggregate function,
(B) one of the "group <b>B</b>y" expressions,
(C) a <b>C</b>onstant, or
(D) something that <b>D</b>epends entirely on the above. (For example, if you "GROUP BY TRUNC(dt)", you can SELECT "TO_CHAR (TRUNC(dt), 'Mon-DD')").
Edited by: Frank Kulash on Apr 13, 2013 1:44 PM
Added code examples.

Problem with the query in group by clause

hi, i have problem with group by clause, can some one please help me.
select
header_id,
(select sum(nvl(dr,0) - nvl(cr ,0)) from temp_tab a1
where
a1.country=a.country
and a1.source='AP'
and a1.header_id=a.header_id) WHT,
sum(dr),
sum(cr) from temp_tab a
group by header_id,
(select sum(nvl(dr,0) - nvl(cr ,0)) from temp_tab a1
where
a1.country=a.country
and a1.source='AP'
and a1.header_id=a.header_id)
select * from temp_tab
drop table temp_tab
create table temp_tab(header_id number ,line_num number, country varchar2(2),
source varchar2(2), dr number, cr number,primary key(header_id,line_num));
insert into temp_tab(header_id, line_num,country, source, dr,cr) values(1, 1,'NL','AP',100,20);
insert into temp_tab(header_id, line_num,country, source, dr,cr) values(1, 2,'PO','AP',20,20);
insert into temp_tab(header_id, line_num,country, source, dr,cr) values(1, 3,'NL','AP',70,20);
insert into temp_tab(header_id, line_num,country, source, dr,cr) values(2, 1,'NL','PA',100,20);
insert into temp_tab(header_id, line_num,country, source, dr,cr) values(2, 2,'NL','PA',100,20);
insert into temp_tab(header_id, line_num,country, source, dr,cr) values(3, 1,'KR','PO',100,20);
commit;
Appreciate your help.
Thanks,

select header_id,
         (select sum(nvl(dr,0) - nvl(cr ,0)) from temp_tab a1
         where a1.country=a.country
         and a1.source='AP'
         and a1.header_id=a.header_id) WHT,
         sum(dr),
         sum(cr)
from temp_tab a
group by header_id
,countryIt's kinda hard to follow what your query does... maybe because I'm only at my second coffee..
Edited by: Alex Nuijten on Oct 2, 2009 8:07 AM

How to set a group by clause in ODI interface?

How to set a group by clause in ODI interface?

In ODI, group by method will be triggered automatically when any one of your mapping contains aggregate functions.
Thanks,
Saravanan Rajavel

Count(*) in select statement having group by clause

Hi
I would like to use count(*) in select statement having group by clause. say for example there is a state with a number of cities listed. I would like to get the count of cities for each state.
the sql stement is grouped by city and it is joined with 5 more tables.
Thanks

I suspect you want to look into analytic functions (assuming you have a recent version of Oracle). asktom.oracle.com has numerous examples if you do a search.
Justin

Oracle 10g group by clause

I have one SQL query using a GROUP BY clause and no ORDER BY clause is used. When executed in Oracle 8i, the query results are returned ordered by first column mentioned in the GROUP BY clause. When the same query is executed in Oracle 10g, the query results are returned withour ordering the data by the first column in the GROUP BY clause. It works only when I explicitly mention the ORDER BY clause. Can you please explain this? In Orcale 8i, is it that, by default, the data is ordered by the first column mentioned in the GROUP BY clause when ORDER BY clause is not mentioned?
In which order does oracle 10g sorts when I use group by clause in oracle 10g

[email protected] wrote:
the use of group by is to group based on some column value, in this case why does the the output differs in rows. why does the output, when you use group by is not the following formatSorry, but this is a totally fruitless topic. Why are you bothering with something that is totally internal to the DBMS? If you want the data ordered, use ORDER BY, it's that simple.
Check out this link, if you want some discussion on it:
[http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:74320098178823]

Analytic Functions with GROUP-BY Clause?

I'm just getting acquainted with analytical functions. I like them. I'm having a problem, though. I want to sum up the results, but either I'm running into a limitation or I'm writing the SQL wrong. Any hints for me?
Hypothetical Table SALES consisting of a DAY_ID, PRODUCT_ID, PURCHASER_ID, PURCHASE_PRICE lists all the
Hypothetical Business Question: Product prices can fluctuate over the course of a day. I want to know how much per day I would have made had I sold one each of all my products at their max price for that day. Silly question, I know, but it's the best I could come up with to show the problem.
INSERT INTO SALES VALUES(1,1,1,1.0);
INSERT INTO SALES VALUES(1,1,1,2.0);
INSERT INTO SALES VALUES(1,2,1,3.0);
INSERT INTO SALES VALUES(1,2,1,4.0);
INSERT INTO SALES VALUES(2,1,1,5.0);
INSERT INTO SALES VALUES(2,1,1,6.0);
INSERT INTO SALES VALUES(2,2,1,7.0);
INSERT INTO SALES VALUES(2,2,1,8.0);
COMMIT;
Day 1: Iif I had sold one product 1 at $2 and one product 2 at $4, I would have made 6$.
Day 2: Iif I had sold one product 1 at $6 and one product 2 at $8, I would have made 14$.
The desired result set is:
DAY_ID                 MY_MEASURE
1                        6
1                       14The following SQL gets me tantalizingly close:
SELECT DAY_ID,
MAX(PURCHASE_PRICE)
KEEP(DENSE_RANK FIRST ORDER BY PURCHASE_PRICE DESC)
OVER(PARTITION BY DAY_ID, PRODUCT_ID) AS MY_MEASURE
FROM SALES
ORDER BY DAY_ID
DAY_ID                 MY_MEASURE
1                      2
1                      2
1                      4
1                      4
2                      6
2                      6
2                      8
2                      8But as you can see, my result set is "longer" than I wanted it to be. I want a single row per DAY_ID. I understand what the analytical functions are doing here, and I acknowledge that I am "not doing it right." I just can't seem to figure out how to make it work.
Trying to do a sum() of max() simply does not work, nor does any semblance of a group-by clause that I can come up with. Unfortunately, as soon as I add the windowing function, I am no longer allowed to use group-by expressions (I think).
I am using a reporting tool, so unfortunately using things like inline views are not an option. I need to be able to define "MY_MEASURE" as something the query tool can apply the SUM() function to in its generated SQL.
(Note: The actual problem is slightly less easy to conceptualize, but solving this conundrum will take me much closer to solving the other.)
I humbly solicit your collective wisdom, oh forum.

Thanks, SY. I went that way originally too. Unfortunately that's no different from what I could get without the RANK function.
SELECT DAY_ID,
        PRODUCT_ID,
        MAX(PURCHASE_PRICE) MAX_PRICE
FROM SALES
GROUP BY DAY_ID,
           PRODUCT_ID
ORDER BY DAY_ID,
           PRODUCT_ID
DAY_ID                 PRODUCT_ID             MAX_PRICE
1                      1                      2
1                      2                      4
2                      1                      6
2                      2                      8

Improving Performance of Group By clause

I'm a developer who needs to create an aggreagate, or roll-up, of a large table (tens of millions of rows) using a group by clause. One of the several items I am grouping by is a numeric column called YEAR. My DBA recommended I create an index on YEAR to improve the performance of the group by clause. I read that indexes only are used when referenced in the where clause, which I do not need. Will my DBA's reccomendation help? Can you recommend a technique? Thank you.

When you select millions of rows, grouped or not, the database has to fetch
each of them, so an index on the group column isn't useful.
If you have a performance problem that cannot be solved through an index on
columns used in your where-clause, perhaps a materialzed view with the
dimension(s) of your group clause will help.

Query Plan 'group-by' clause

In evaluating several query plans, I've discovered several sqlstop messages that read:
<groupBy preclustered="true" sqlstop="Cannot generate SQL for the 'group-by' clause because it is not equivalent to the relational GROUP BY clause" stable="true">
I've examined the XQuery code and find no group clause and I can't find a reference to this message in the documentation or by googling the text. I assume that the grouping is being done implicitly by ODSI since it is not in the XQuery source. I have tried restructuring the code to no avail.
My question is -- is this causing me a performance problem since the sql is not generated, and if so, what steps must I take in the xquery structure to avoid this issue.
Many thanks to anyone who can provide some insight into this.
Regards,
PB

is this causing me a performance problem since the sql is not generatedMy question is - why are you asking this question? :) Do you have a performance problem? The "Best Practices" posted as an announcement in this forum might help. Otherwise engage customer support.
To answer your question - your xquery likely generates nested/hierarchical xml - and looks something like below - which can be implemented with a sql left-outer-join ordered by CUSTOMER_ID of the customer-table, and taking the rows returned and ... grouping by CUSTOMER_ID to eliminate the duplicate customer information. So there's your group-by. But you cannot write sql that has a left-outer join, and then a group-by on the left-hand side. So the group by is done in the engine. Since the results are already sorted, the group-by in the engine simply skips over the duplicates (i.e. it's basically free).
for $c in CUSTOMER()
where $c/LAST_NAME = $lastname
return
<CUSTOMER>
... $c/CUSTOMER_ID ... (: in a left-outer-join, the CUSTOMER_ID is duplicated for every ORDER :)
{ for $o in ORDER()
where $o/CUSTOMER_ID eq $c/CUSTOMER_ID
return
</CUSTOMER>

Alternate to group by clause

Similar Messages

Maybe you are looking for