I´m doing a paginated query using the following template:
select * from (select rownumber() over
( order by aaa.x ) as rownum, aaa.abc, aaa.bcd,bbb.cde from aaa as aaa
left join bbb on aaa.colx= bbb.coly where aaa.where1 = 'xxx'
) as tempresult where rownum between 101 and 200
Assuming a page size of 100 items, the first page query would be the same thing, replacing the rownum condition for:
where rownum <= 100
I´m facing a situation where the first page performs very well ( <1s ), but when we move from the second page-forward the query takes about 5-6s.
Can anyone explain me why is that the case?
Is there any way to slight modify this query template in order to achieve better performance?
Is there any complete different strategy that could perform better?
Additional Info:
I use DB2 v9.7.400.501
There´s no limit keyword
I cannot create views or stored procedures due to a customer constraint
I cannot create any additional indexes
Tried switching from rownumber() no rank() but it didnt change anything
You will need to look at both queries' execution plans to see if there is any difference -- only that can give you a definite answer.
You could try rewriting the query like so:
select * from (
select rownumber() over ( order by aaa.x ) as rownum, aaa.abc, aaa.bcd
from aaa as aaa
where aaa.where1 = 'xxx'
) as tempresult
left join bbb on tempresult.colx= bbb.coly
and tempresult.rownum between 101 and 200
Edit:
Nothing prevents you from using columns from bbb in the final select:
select tempresult.*, bbb.cde
from (
select rownumber() over ( order by aaa.x ) as rownum, aaa.abc, aaa.bcd
from aaa as aaa
where aaa.where1 = 'xxx'
) as tempresult
left join bbb on tempresult.colx= bbb.coly
and tempresult.rownum between 101 and 200
Related
We have a code to sort data and paginate the same and render the data to a Jqgrid. The code works fine when it is connected to an SQL server. That is on paginating each page returns distinct data as expected. But on connecting to an oracle server after some point of time the duplicate data are rendered. Both Oracle and SQL server has same data. Parameters in the Jqgrid page and the number of pages are working as expected on the server-side. That is on paging the start point and chunk size is correctly transferred to the server-side. The duplicate values are observed after sorting columns that are of type varchar in the database but hold numeric also. The database status column holds values of 3 and A, after sorting with the status column the duplicate data when the paginating issue is observed. Duplicate data in the sense, that data on page 2 will be the same as data on page 3. Any help will be appreciated. Thanks in advance...
Query One:-
select * from ( select row_.*, rownum rownum_ from ( Select x,y,z,status FROM tablename c WHERE status IN('in condition seperated with status') ORDER BY status asc ) row_ where rownum <= 30 ) where rownum_ > 20;
Query Two:-
select * from ( select row_.*, rownum rownum_ from ( Select x,y,z,status FROM tablename c WHERE status IN('in condition seperated with status') ORDER BY status asc ) row_ where rownum <= 20 ) where rownum_ > 10;
Here the query 1 and 2 always return the same results.
Where two or more values in the column of your ORDER BY clause are the same, you must always provide another secondary column to rank. Otherwise, data return has only a probability of fetching correct result as we expect. The possibility of getting a correct answer will be same as rolling a dice. The secondary column must be unique for accurate results. While you might be able to assume that they will sort themselves based on order entered
select * from( select row_.*, rownum rownum_ from( Select x,y,z,status FROM tablename c WHERE status IN('in condition seperated with status') ORDER BY status,x asc ) row_ where rownum <= 30 ) where rownum_ > 20;
Hoping x is a unique value. DBMS_RANDOM.VALUE can also be used in case if is an oracle specific query other than adding extra order by clause
I'm wondering if it's possible to pass one or more parameters to a WITH clause query; in a very simple way, doing something like this (taht, obviously, is not working!):
with qq(a) as (
select a+1 as increment
from dual
)
select qq.increment
from qq(10); -- should get 11
Of course, the use I'm going to do is much more complicated, since the with clause should be in a subquery, and the parameter I'd pass are values taken from the main query....details upon request... ;-)
Thanks for any hint
OK.....here's the whole deal:
select appu.* from
(<quite a complex query here>) appu
where not exists
(select 1
from dual
where appu.ORA_APP IN
(select slot from
(select distinct slots.inizio,slots.fine from
(
with
params as (select 1900 fine from dual)
--params as (select app.ora_fine_attivita fine
-- where app.cod_agenda = appu.AGE
-- and app.ora_fine_attivita = appu.fine_fascia
--and app.data_appuntamento = appu.dataapp
--)
,
Intervals (inizio, EDM) as
( select 1700, 20 from dual
union all
select inizio+EDM, EDM from Intervals join params on
(inizio <= fine)
)
select * from Intervals join params on (inizio <= fine)
) slots
) slots
where slots.slot <= slots.fine
)
order by 1,2,3;
Without going in too deep details, the where condition should remove those records where 'appu.ORA_APP' match one of the records that are supposed to be created in the (outer) 'slots' table.
The constants used in the example are good for a subset of records (a single 'appu.AGE' value), that's why I should parametrize it, in order to use the commented 'params' table (to be replicated, then, in the 'Intervals' table.
I know thats not simple to analyze from scratch, but I tried to make it as clear as possible; feel free to ask for a numeric example if needed....
Thanks
I have a table with following data
Code Dest
atp ananthapur
blr bangalore
chn chennai
del delhi
hmp himachal
hyd hyderbad
goa goa
I need a query to fetch data such that the rows for codes 'hyd' and 'blr' would remain on top always, and then rest of the rows will follow.
I have done this as below -
select code,dest from (
select 1 rown,a.* from LOCATION a
where a.code in ('hyd','blr')
union
select 2 rown,b.* from LOCATION b
where b.code not in ('hyd','blr')
)
order by rown
I can think of doing it in some other ways also. But my question is -
Is there any oracle defined feature to accomplish this?
Yes, Oracle has such a feature, it's the ORDER BY expressions-list clause.
Try:
SELECT * FROM LOCATION a
ORDER BY
CASE WHEN a.code in ('hyd','blr') THEN 1 ELSE 2 END
A weird request maybe but. My boss wants me to create an admin version of a page we have that displays data from an oracle query in a table.
The admin page, instead of displaying the data (query returns 1 row), needs to return the table name and column name
Ex: Instead of:
Name Initial
==================
Bob A
I want:
Name Initial
============================
Users.FirstName Users.MiddleInitial
I realize I can do this in code but would rather just modify the query to return the data I want so I can leave the report generation code mostly alone.
I don't want to do it in a stored procedure.
So when I spit out the data in the report using something like:
blah blah = MyDataRow("FirstName")
I can leave that as is but instead of it displaying "BOB" it would display "Users.FirstName"
And I want to do the query using select * if possible instead of listing all the columns
So for each of the columns I am querying in the * , I want to get (instead of the column value) the tablename.ColumnName or tablename|columnName
hope you are following- I am confusing myself...
pseudo:
select tablename + '.' + Columnname as WhateverTheColumnNameIs
from Table1
left join Table2 on whatever...
Join Table_Names on blah blah
Whew- after writing all this I think I will just do it on the code side.
But if you are up for it maybe a fun challenge
Oracle does not provide an authentic way(there is no pseudocolumn) to get the column name of a table as a result of a query against that table. But you might consider these two approaches:
Extract column name from an xmltype, formed by passing cursor expression(your query) in the xmltable() function:
-- your table
with t1(first_name, middle_name) as(
select 1,2 from dual
), -- your query
t2 as(
select * -- col1 as "t1.col1"
--, col2 as "t1.col2"
--, col3 as "t1.col3"
from hr.t1
)
select *
from ( select q.object_value.getrootelement() as col_name
, rownum as rn
from xmltable('//*'
passing xmltype(cursor(select * from t2 where rownum = 1))
) q
where q.object_value.getrootelement() not in ('ROWSET', 'ROW')
)
pivot(
max(col_name) for rn in (1 as "name", 2 as "initial")
)
Result:
name initial
--------------- ---------------
FIRST_NAME MIDDLE_NAME
Note: In order for column names to be prefixed with table name, you need to list them
explicitly in the select list of a query and supply an alias, manually.
PL/SQL approach. Starting from Oracle 11g you could use dbms_sql() package and describe_columns() procedure specifically to get the name of columns in the cursor(your select).
This might be what you are looking for, try selecting from system views USER_TAB_COLS or ALL_TAB_COLS.
I need to get the result of concatenating 2 similar querys' resulsets. For some reason had to split the original query in 2, both with their corresponding order by clause. Should be something like (this is an oversimplification of the original queries)
Query1: Select name, age from person where age=10
Resultset1:
Person1, 10
Person3, 10
Query2: Select name, age from person where age=20
Resultset1:
Person2, 20
Person6, 20
The expected result:
Person1, 10
Person3, 10
Person2, 20
Person6, 20
I can not simply use Query1 UNION Query2.
Below the 2 original querys:
(#1)
select cp.CP_ID, cpi.CI_DESCRIPCION, cp.CP_CODIGOJERARQUIZADO, cp.CP_ESGASTO as gasto, cp.CP_CONCEPTOPADRE, LEVEL
from TGCCP_ConceptoPagoIng cp
left join tgcci_ConceptoPagoIngIdioma cpi on cpi.CI_IDCONCEPTOPAGOING = cp.CP_ID and cpi.CI_IDIDIOMA = 1
start with ((CP_CONCEPTOPADRE is null) and (**cp.CP_ESGASTO = 1**))
connect by prior cp.CP_ID = cp.CP_CONCEPTOPADRE
order siblings by CP_CODIGOJERARQUIZADO
(#2)
select cp.CP_ID, cpi.CI_DESCRIPCION, cp.CP_CODIGOJERARQUIZADO, cp.CP_ESGASTO as gasto, cp.CP_CONCEPTOPADRE, LEVEL
from TGCCP_ConceptoPagoIng cp
left join tgcci_ConceptoPagoIngIdioma cpi on cpi.CI_IDCONCEPTOPAGOING = cp.CP_ID and cpi.CI_IDIDIOMA = 1
start with ((CP_CONCEPTOPADRE is null) and (**cp.CP_ESGASTO = 2**))
connect by prior cp.CP_ID = cp.CP_CONCEPTOPADRE
order siblings by CP_CODIGOJERARQUIZADO
I think you want a
select * from ( first query )
UNION ALL
select * from ( second query )
Where first query and second query are the queries from above, so you are turning them into subqueries, thus preserving the order by clauses.
OK, well, I'm not fully certain why you need it this way, but if Oracle won't allow you to do a UNION, or it screws up the ordering when you do, I would try creating a pipelined table function.
An example here
Basically, you'd create a procedure that ran both queries, first one, then the other, putting the results of each into the returned dataset.
It looks like you are looking for a MULTISET UNION. Which can only be used from version 10 upwards.
Regards,
Rob.
You could combine your queries as subqueries and do a single order by on the outer query:
select * from (
<query 1 with its order by>
UNION ALL
<query 2 with its order by>
)
order by column1, column2;
Alternatively, you can implement in PL/SQL the equivalent of a sort merge join with two cursors, but that's unnecessarily complicated.
this solution works perfectly:
select * from ( first query )
UNION ALL
select * from ( second query )
I appreciate everyone that have taken the time to answer.
regards.
For your example:
Select name, age from person where age in (10,20)
or
Select name, age from person where age = 10 or age = 20
However I'm guessing this is not what you need :)