SQL & PL/SQL :: Bitmap Or B-Tree Index?
Apr 9, 2010
I was executing following query and it was taking about 20 sec's to execute before i decided to create B-Tree(Normal) index on column DeliVery.
Select
DeliVery,Code,Sum(Units),Sum(Loads),Count(units),
Count(Loads)
Where
[code]...
After creating B-Tree index on Column Delivery the execution time has been reduced to one second ,thats what i wanted. But If i create Bitmap index on the same column then execution time is not getting reduced and is still same around 20 sec.I think theoratically "Delivery" column is the right candidate for Bitmap index? whether should i create bitmap index or stick with B-Tree index?
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Oct 20, 2012
I am using ORACLE 11gR1.
I was running a test on a huge table with a bitmap index on one of the columns. But bitmap index is not getting used. Below are the test details.
create table test (col1 number, col2 number);
begin
for i in 1..1000000
loop
if mod(i,2) = 0 then
insert into test values(i, 'Y');
else
insert into test values(i, 'N');
end if;
end loop;
end;
COMMIT;
The intention here is to have only two distinct values in the entire table. Based on these values I will not build BITMAP index on col2.
CREATE BITMAP INDEX BITMAP_TEST on TEST(col2) COMPUTE STATISTICS;
Now when I run the below query, it doesn't uses BITMAP index. Instead the explain plan shows a full table scan.
select * from test where col2 = 'Y';
Now when I force ORACLE to use index through hint, the cost is too high while using the bitmap index(probably why the ORACLE chose not to use the index at the first stage).
I have read somewhere, that BITMAP index is useful when we have more than 1 or 2 bitmap indexes on other columns of the same table as well And the query should be like
select * from table where col1 = 'Y' and sex = 'F';
In this case oracle will use BITMAP but not in the case where there is only one column that has BITMAP index.
Considering all the factors stated above, is there any way I can fine tune my original query?
select * from test where col2 = 'Y';
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Jan 27, 2013
i want to create a bitmap index,but getting the error shown below..i created primary key on column dname of dept and unique constraint on empno of emp.
SQL> create bitmap index bindx on dept d(d.dname) from emp e,dept d where e.deptno=d.deptno;
create bitmap index bindx on dept d(d.dname) from emp e,dept d where e.deptno=d.deptno
*
ERROR at line 1:
ORA-25954: missing primary key or unique constraint on dimension
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Dec 26, 2011
index types like cluster,bitmap,binary tree,functional. Specify the differences between these types
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Dec 3, 2012
I have an IOT table with partitioned on list. I have p1,p2 and p3 partitions. Now I would like to create a bitmap index on partition key.
I gave ALTER TABLE .. MOVE MAPPING TABLE;
But getting the below error,
ORA-28660: Partitioned Index-Organized table may not be Moved as a whole.
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Nov 15, 2012
oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
PL/SQL Release 11.1.0.6.0 - Production
"CORE 11.1.0.6.0 Production"
I have a procedure that is run weekly to load the data, for which it calls another procedure. This weekly procedure, disables the index, load the data, and rebuilds the index. During rebuilding of index, its giving ORA-00054: resource busy and acquire with NOWAIT error. I dont have privileges to look for session id, and kill the session. How to avoid this error.
create or replace
PROCEDURE "WCL_WEEKLY_UPLOAD" (
p_event_id IN NUMBER
)
[code]....
As you can see, after the procedure wc_upload, COMMIT is issued, and then the rebuilding of the index is starting. So dont know what is causing the table to lock.
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Jul 11, 2012
I am using Oracle 10g XE (express edition). If I try to create a bitmap index, I get an error
ORA-00439 feature not enabled: Bit mapped Indexes
How do I solve this problem and create a bitmap index?
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Jan 10, 2012
we have a strange symptom in a database Oracle 11.2.0.2 EE. Following question comes from our application developers.
The following SQL statement:
SELECT
v.reporting_month,
sum(v.f_s) "REV_S",
sum(v.f_f) "REV_F",
sum(v.f_c) "REV_C",
[code].......
gives different result when we exchange the index ksr_valid_until_i on table kreditkarten_sets_rs. For some reasons we changed the index from bitmap to normal and are getting different results. Switching back gives us the same results as before. When we avoid the usage of this index in the statement than we are getting the same results as when we are using the normal index.
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Feb 20, 2013
Version Info: 11.2 on Solaris 10
I have a partitioned table like below. I want to create a B-Tree index on SALES_RGN column which is neither the part of Primary key or the Partitioned key. Should I create this index as local or Global ?
CREATE TABLE sales_dtl
(
txn_id number (9),
salesman_id number(5),
salesman_name varchar2(30),
sales_rgn varchar2(10), -----------------------------> This column needs to be indexed
sales_amount number(10),
sales_date date,
constraint pk_sales_dtl primary key (txn_id)
[code]....
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Jul 19, 2012
What should be the order of columns while creating b-tree non-unique index.
Low cardinality first
or
Hight cardinality first
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Jul 23, 2013
is there some performance/access difference between a bitmap index on a number column and char(1) column? Both columns are not null with a default value.My application has a querie like this:
select ass.column20, ass.column30from table_a pucinner join table_b asson ass.column1 = puc.column1where pc.column_char = 'S'and ass.column_char02 = 'P'
If I create a bitmap index on column "column_char", the access plan is not changed. But changing the column datatype to number(1) and obviously the values, the index is accessed and the cost decreases.This table has 4.000.000 rows. Oracle 11.2.0.2SO
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Jul 1, 2011
I have 2 sets of phone number ranges and need to find the ranges that intersect.
create table rng1
(
rng_start varchar2(10),
rng_end varchar2(10)
);
[code]....
When I try to find the ranges matching (intersecting) a certain range (e.g. '21112'-'2111299999'), optimizer does a FULL TABLE SCAN, which is not opimal in my opinion. I use the hint to force the optimizer use the indexes.
select /*+ index_combine(rng2 x_rng2_start, x_rng2_end) */ *
from rng2
where
rng2.rng_start <= '2111999999'
and rng2.rng_end >= '2111';
Plan
SELECT STATEMENT ALL_ROWSCost: 60 Bytes: 17,344 Cardinality: 1,084
7 TABLE ACCESS BY INDEX ROWID TABLE LUMAMIPA.RNG2 Cost: 60 Bytes: 17,344 Cardinality: 1,084
6 BITMAP CONVERSION TO ROWIDS
5 BITMAP AND
2 BITMAP MERGE
1 BITMAP INDEX RANGE SCAN INDEX (BITMAP) LUMAMIPA.X_RNG2_START
4 BITMAP MERGE
3 BITMAP INDEX RANGE SCAN INDEX (BITMAP) LUMAMIPA.X_RNG2_END
However, when I try to join the 2 sets of ranges by matching the intersecting ranges, then the range scan and "BITMAP AND" of the 2 indexes is not done, even though the hint is specified:
select /*+ index_combine(rng2 x_rng2_start, x_rng2_end) */
count(*) cnt
from rng1
join rng2 on
rng1.rng_start <= rng2.rng_end
and rng1.rng_end >= rng2.rng_start;
[code]...
How to make the optimizer use the range scan of both indexes? Is there a better way to match the ranges?
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Aug 1, 2007
what does a bitmaped block represent in oracle9i.
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Jul 18, 2013
I have a few dimension tables with surrogate keys and a fact table with foreign keys on columns referring to the dimension table. I want to create primary keys on the dimension tables and foreign keys on the fact table, but with minimal overhead of constraint validation when loading the data.
Other than bitmap indexes on the FK columns on the fact table, I also want to create a bitmap join index on the fact table joined to the dimension table on a handful of dimension columns.
Which is the best suited constraint definition? Only RELY, or RELY + DISABLE, or RELY + DISABLE + NOVALIDATE, or RELY + NOVALIDATE, or any other?
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Jul 24, 2012
Are NULLs get indexed in bitmap indexes? How can I verify that.
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Mar 16, 2011
I am running oracle Apps 11.5.10.2, trying to enable duplex printing for all PDF / XML reports.
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Jan 24, 2012
I have added a bitmap image in my workbook but when i am exporting it into excel or HTML ,only text part of the title is exporting into excel file . The bitmap is only visible in discoverer workbook ,after exporting to excel or HTML, it disappears,
i am using oracle 9i discoverer version 9.0.2.0.
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Feb 4, 2005
16:28:32 SQL> create bitmap index bp_idx_ag_id on transactions(type);
create bitmap index bp_idx_ag_id on transactions(type)
*
ERROR at line 1:ORA-25122: Only LOCAL bitmap indexes are permitted on partitioned tables
how to create bitmap index on partitiioned tables
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Jun 27, 2012
I am on 11.2.0.3 Enterprise Edition. We are using the new feature "Composite Domain Index" for a Domain index on a very large table (>250.000.000 rows). It really works with mixed queries. We added two number columns using FILTER BY.We have lots of DML on this table. Therefore, we are executing synchronize and optimize once the week. The synch behaves pretty normal. But "optimize_index" takes a very very long time to complete. I have switsched on 'logging' for the optimize process. The $I table takes some time but is finished normally. But the optimization of the $S table (that is the table created for the CDI feature) is running over 12 hours now - and far from being finished. From the logfile, I can see that it optimizes 1000 rows every 20 minutes. Here is the output of the logfile:
Oracle Text, 11.2.0.3.0
14:33:05 06/26/12 begin logging
14:33:05 06/26/12 event
14:33:05 06/26/12 process $N for optimize: SEQDEV.GEN_GES_DESCRIPTION_CTX_I
14:33:16 06/26/12
14:33:16 06/26/12
[code]....
I haven't found a recommendation from Oracle not to use "optimize_index" for Domain Indexes with CDI. But in my case, it would be much faster just to drop and recreate the Domain Index in question.
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Jun 28, 2011
I have a huge table (about 60 gb) partition over range. The index on this table is global index created on 4 columns together. I have a query which is running very slowly. The explain plan is showing the use of this global index.Explain plan is not showing pstart and pend because the index is global.
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Jun 23, 2011
I have a global index and I want to convert it to local index.Is there a way to recreate local index with out dropping the global index.
I can create a local index first and then drop the global index. But is there a way to create it with out dropping the global index, just convert it.
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Nov 29, 2010
I am facing the error "ORA-01502: index or partition of such index is in unusable state " while loading the text data using
sql loader with direct path (direct = Y ,rows = 10000) option. Table consists an composite non unique index. If I query the dba indexes for the effected index it shows the index status as VALID. There was no maintaince done on the effected table or index. I have tried loading the same data using conventional path but didn't found any issues for the same.
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Nov 19, 2010
I have a query which had a join:
a.c1=b.c1 and a.c2=@var
where @var is user supplied input at runtime...We had a index on a.c2 . The CBO would use this index to generate an opitimised query plan.We found some records from table "b" were dropping due to inner join. So we made a change in join. It'd be like
a.c1(+)=b.c1 and nvl(a.c2,@var)=@var
This query is no longer using the index, instead its doing a full table scan causing the query to slowdown.I have tried creating index on nvl(a.c2,'31-dec-9999')
But the CBO won't use it.Anyway to create index on this col so that full table scan can be avoided?
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Aug 9, 2013
How to force an index if the table not using the index?
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Aug 27, 2012
We have occurrences of enq : TX - index contentions in the database. Using the SQL ID, we have identified the INSERT statement and the table which they are trying to insert.
This table has almost 25 different indexes, some of which are unique as well.I am wondering how to identify the actual index causing issue, out of these 25 indexes.
Is there any way to pin point to the name of index which is causing the lock?My plan is, once the index is identified, I would like to check the extents and inittrans and other attributes of this index to fix.
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Sep 20, 2013
I need to form XML for hirarchy data,
CREATE TABLE TESTING (
EMPID VARCHAR2(1),
ENAME VARCHAR2(10),
CHILD_ID NUMBER,
PARENT_ID NUMBER);
INSERT INTO TESTING VALUES ('A', 'AText', 1001,0);
INSERT INTO TESTING VALUES ('B', 'BText', 1002,1001);
INSERT INTO TESTING VALUES ('C', 'CText', 1003,1002);
insert into testing values ('D', 'DText', 1004,1003);
SELECT LEVEL, EMPID,ENAME,CHILD_ID, PARENT_ID
FROM TESTING
START WITH PARENT_ID = 0
CONNECT BY NOCYCLE PRIOR CHILD_ID = PARENT_ID;
Need select query to return output like below
<ITEM ID="A" TEXT="AText" IM0="folderClosed.gif" CHILD="1">
<ITEM ID="B" TEXT="BText" IM0="folderClosed.gif" CHILD="1">
<ITEM ID="C" TEXT="CText" IM0="folderClosed.gif" CHILD="1">
<ITEM ID="D" TEXT="DText" IM0="folderClosed.gif" CHILD="1">
</ITEM>
</ITEM>
</ITEM>
</ITEM>
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Jul 11, 2012
Can we create non-cluster index on a clustered index?
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Sep 8, 2012
Explain the following query to me:
in particular Lpad (' ', Level-1)*3.
select lpad(' ' , (level-1)*3) || emp_last_name employee
from emp
connect by supervisor_emp_id = prior emp_id
start with supervisor_emp_id is null;
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Dec 24, 2012
Hierarchical Tree in oracle form 6i .i am trying to build tree in form 6i but it give error
SELECT 1,
level,
job
,
'',
ename
FROM emp
START WITH mgr IS NULL
CONNECT BY PRIOR empno = mgr
order by level
i want to show job wise employees ...
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Nov 25, 2012
My table structure is like this
CREATE TABLE Tab1(LVL1_NM VARCHAR2(20), LVL2_NM VARCHAR2(20), LVL3_NM VARCHAR2(20), LVL4_NM VARCHAR2(20))
and the values will be for one value of LVL1_NM there will be different LVL2_NM values like wise for each and every value of LVL2_NM column there will different values in LVL3_NM column like wise for LVL4_NM is there any way to get the results as per their relation ships.
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