PL/SQL :: Bitmap Index On Number Column X Char Column?
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:
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
I need to create a composite unique index on varchar2, number and CLOB column. I haven't used such index before that have the CLOB column indexing. I found the below link related to CLOB indexing...
[URL]......
Links from where I can get related info. Also I would like to know the impact of such index on performance. I have to store and process around 50 million records in such a way, will it be beneficial to use this index?
I have one hirarchical query which return the parent to child hirarch level data. it has 11 level child data. i want to create column based on number of child in hirarchy. though i know it is 11 but it can change also.Is there any way i can create the column dynamically
We are using Oracle 11g with Apex 3.2 on AIX. We are reporting data from customer satisfaction surveys. I'm using the following sql to create my report
<code>select * from( select month,'Overall Satisfaction' as q_group, 1 as srt,Overall Satisfaction,site, case when count(*) < 31 then '*' else round((sum(ttos)/count(*))*100,0)||'/'|round((sum(bfos)/count(*))*100,0)||'/'||count(*) end ospct from v_XXX_report a,(select distinct month_dt month from v_XXX_report) b where Overall_Satisfaction is not null and year_dt = 2012
[Code]....
The problem is that site is not allways present and sometimes I have other variables in addition to site. This creates a situation where the month columns will not allways appear at the same column number. For example, When I run this query as is then the "JAN" column is Col3 (first column is a break, col2 is not shown). When I run this query without site then "JAN" is the second column. I would like to create column links for the "JAN" - "DEC" columns but not for any other columns.
Another issue - in the column link creation screen I can create up to 3 variables that I can pass to the next page. Since my query is a pivot I'm uncertain how to pass the column heading or the row value (for col2)
ie Overall Satisfaction JAN FEB MAR APR MAY ... Overall Satisfaction 12/12/200 12/12/210 12/12/220 12/12/230 12/12/240... Recommend 12/12/200 12/12/210 12/12/220 12/12/230 12/12/240... etc.
So if I clicked on the values at Recommend:FEB how can I get "Recommend" and "FEB" into variables that I can use on the next page? I've tried #column_name#, #month#, #q_name# and #APEX_APPLICATION.G_F10# but no luck.
I have a table where i have description column which free text column, the data in description column is seperated and i want to corvert 1 row data in multiple rows dependeing on the number of words.
eg
id description 78664 Pumps Alarm from CAMS RTU154
In the above example this column has 5 word so i want data in 5 rows like below
78664 Pumps 78664 Alarm 78664 from 78664 CAMS 78664 RTU154
This column data can be varied from 1 to any number of words.
I have a partitioned table with ~50 million rows that was setup with a number(10) instead of a date column. All the data in the table is ALWATS in this format YYYYMMDD
CREATE TABLE T1.monthly ( SEQ_NUM NUMBER(10) NOT NULL, DAY_DK NUMBER(10) NOT NULL ) TABLESPACE USERS PCTUSED 0 PCTFREE 10 [code]........
When I use the exchange partition method the parition is able to move the data from "monthly" table to "mth" table.
desc t1.mth; ### my temorary table Name Null? Type ----------------------------------------- -------- ---------------------------- SEQ_NUM NUMBER(10) DAY_DK NUMBER(10)
Than when I try to alter my temp table "mth". I get an error table must be empty to change column types.
alter table n546830.mth modify (DAY_DK date);
Next I tried making my temporary table "mth" a date column. When I an the exchange partition command I get the following error:
alter table t1.monthly exchange partition DEC_2012 with table t1.mth without validation; alter table n546830.monthly exchange partition DEC_2012 with table n546830.mth without validation * ERROR at line 1: ORA-14097: column type or size mismatch in ALTER TABLE EXCHANGE PARTITION
Method I can use to convert a number(10) to date column and keep the information in a table. Note, I don't care about HH:MM:SS as I never had that information to begin with and would be happy to set that part of the date column to all zeroes "00:00:00"
I have one issue while loading the value through sql*loader the last column data is SG1 and when its loaded , it is length of this columns is showing 4 char. Unable to understand, how to find this extra space. Though used TRIM but does not work.
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?
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?
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
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.
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.
My requirment is to find out the period names and transactions which are in valid date formats and are less than sysdate and the non date formats are adjustments made by different users for their transactions
my column type is NUMBER(10,0) ,it accept the input value from text field I using TO_NUMBER(?) to insert value into table, is the a way to handle if the input is 'aaaaaaaaaa' not digit?
I have a table with column A which contains very few null values. I need to select these rows. I am considering two options:
a) create function based index on NVL(A, 0) and use this in where clause NVL(A, 0)=0 (column doesn't have values 0) b) create function based index on NVL2(A, 0, NULL) and and use this in where clause NVL2(A, 0, NULL) = 0
First idea was option A. But I realized in option B the index will be much smaller, because most of values of column A isn't NULL so NVL2 will return NULL and index will not have as much leafs as in NVL. It is good idea to use NVL2? Is there any against to use option B instead of A?
SQL > CREATE UNIQUE INDEX index_debug1 ON debug_table (SLNO);
Index created.
SQL > ALTER INDEX index_debug1 ADD COLUMN MESSAGE; ALTER INDEX index_debug1 ADD COLUMN MESSAGE * ERROR at line 1: ORA-02243: invalid ALTER INDEX or ALTER MATERIALIZED VIEW option
If my query is under execution and I want to make an index on a column which is very much needed by my query. Will a simple index solve the purpose or is there any extra keyword required ?
I currently have a 5 column index on a table with over 2 billion records (paritioned on created_date (weekly) that is not very effective.I am contemplating replacing this 5 key index and creating a new single column index made up by hashing of all the 5 five columns.
Is this a wise stratgey? How can I implement this so it is most effective and I dont shoot myself in the foot?
I have a table with, for example, three columns: A, B,C.
I execute on this table only one select: CODESELECT * FROM TABLE WHERE A = :1 AND B=:2
Column A has a lot of distinct values (numbers), but B can have only two values: 'Y' or 'N' (cardinality about 50%/50%). It is worth to create index on two columns: A, B? Does query using index on A column will be much slower than using index on A, B?
I have in my database (OLTP-System) a table with about 6000000 records and a zise of about 2GB.
the way to create multi_column indexes on the table?
What are the rule to define the best-position of a column in an index?
index_1(col_1,Col_2,col_3) and not [ (col_1,Col_3,col_2) or (col_2,Col_3,col_1) or (col_2,Col_1,col_3) or (col_3,Col_2,col_1) or (col_3,Col_1,col_2) ] ?
I am creating an index in program and then drop the index at the end of the program. Some times due to some problem if the index could not be dropped and the user again runs the program then we get the error
ORA-01408 Index already exist on the column.
how I can get away with this error or how I can check whether the index with the same columns exits prior to creating an index.
explain slow performance of multicolumn indexes on oracle 11g R2 observed in the following scenario? A multi-column index (b-tree index) not partitioned, not unique, not reversed with 3 columns.
A series of queries are run using all 3 columns. The performance hit comes when the first order column values changes. So, maybe after 10 select queries the value changes. The 2nd and 3rd order columns are changing throughout the series of select calls, but no performance bottleneck it hit then.
SELECT CURRENTSTEP FROM (SELECT ( WFENTRY.NAME || ',' || CURRENTSTEP.STEP_ID ) AS CURRENTSTEP, (CASE WHEN WFENTRY.NAME IN
[Code]...
in this query I am concatenating tow columns , I use this query as a sub query in my other queries and filter the results with and CURRENTSTEP = ?
here is how I use it
select sys_audit_id from ( SELECT * FROM (SELECT F.FINDING_NUMBER,
[Code]....
I saw adding this as a subquery with the filter and CURRENTSTEP = ? is slowing my query very much , as this is a derived column i cannot add index then how to improve performance for this subquery ?
I have a table A with a column B timestamp(6). The tables contains around 300000 rows..I have created index 'idx' on the column B.When i compare column 'B' with systimestamp, it does not use the index, whereas if i compare 'B' with sysdate it uses the index.
Eg : select count(*) from a where b<=sysdate;
The above used the index 'idx' and executed in 1 second
select count(*) from a where b<=systimestamp;
The above does not use the index and executed in 19 seconds.
