Suppose i have two columns ID and Status (or any number of columns ) belongs to table customer. Now I want to create below index
Ex. create index test1 on customer (ID , Status )
But before creating this index i want to check that whether there is already index on these 2 columns ? May be by other name ?
I need query to find the missing dates between two columns in given month.
CREATE TABLE emp_shift (
empno NUMBER(4),
fr_date DATE,
TO_DATE DATE,
shift VARCHAR2(1));
CREATE TABLE emp (
empno NUMBER(4)
);
[code].....
Required output is
MISSING_DATES EMPNO
---------------------- ----------
09-SEP-12 TO 11-SEP-12 7499
23-SEP-12 TO 26-SEP-12 7499
01-sep-12 TO 30-SEP-12 7521
01-sep-12 TO 30-SEP-12 7788
I am running a fairly busy Oracle 10gR2 DB, one of the tables has about 120 columns and this table receives on average 1500 insertions per second. The table is partitioned and the partitioning is based on the most important of the two timestamp columns. There are two timestamps, they hold different times.
Out of these 120 columns, about 15 need to be indexed. Out of the 15 two of them are timestamp, at least one of these two timestamp columns is always in the where clause the queries.
Now the challenge is, the queries we run can have any combination of the 13 other columns + one timestamp. In reality the queries never have more than 7 or 8 columns in the where clause but even if we had only 4 columns in the where clause we would still have the same problem.
So if I create one concatenated index for all these columns it will not be very efficient because after the 4th or 5th column the sorting would no longer be very useful and I believe the optimiser would simply not use the rest of the index. So queries that use the leading columns of the index in sequence work well, but if I need to query the 10th column the I have performance issues.
Now, if I create multiple single column indexes oracle will have to work a lot harder to maintain all these indexes and it will create performance issues (I have tried that). Besides, if I have multiple single column indexes the optimiser will do nested loops twice or three times and will hit only the first few columns of the where clause so I think it will kind of be the same as the long concatenated index.
What I am trying to do is exactly what the Bitmap index would do, it would be very good if I could use the AND condition that a Bitmap index uses. This way I could have N number of single column indexes which the optimiser could pick from and serve the query with exactly the ones it needs. But unfortunately using the Bitmap index here is not an option given the large amount of inserts that I get on this table.
I have been looking for alternatives, I have considered creating multiple shorter concatenated indexes but this still would not address the issue since many queries would still not be served properly and therefore would take a very long time to complete.
What I had in mind would be some sort of multidimensional index, I am not even sure if such thing exists. But essentially it would be some sort of index that could serve a query efficiently regardless of the fact that the where clause has the 1st, 3rd and last columns of the index.
So considering how widely used Oracle is and how many super large databases there are out there, this problem must be common.
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?
I have a two question.
Question 1:How to select all columns from table except those columns which i type in query
Question 2:How to select all columns from table where all columns are not null without type each column name which is in empty data
Is there a way to find the tablespace used by an index?
View 4 Replies View RelatedI have a table with a non-unique index consisting of three columns. The first column is not null while the remaining two are nullable. Queries using this index will chiefly be made in two ways.
1. Column one and two having values. Column three is null.
2. Column one and thre having values. Column two is null.
In both cases I expect range scan will be used since it's non-unique. In the first case the scan will be on values in column one and two. But what happens in case two. Will the range be on colum one, column two(being null) and cxolumn three? Or will it be on just column one since the second column is null? I have done some testing. I can see , using EXPLAN PLAN, that range scan is used in both cases. how the index is used?
Is there any other drawbacks with an index like this?
I have two tables like below-
CREATE TABLE prod_vendor_record (
vendor_record_seq_no NUMBER NOT NULL,
study_seq_no NUMBER NOT NULL,
vendor_subject_seq_no NUMBER NULL,
control_dataset_seq_no NUMBER NOT NULL,
checksum NUMBER NOT NULL,
processing_flag VARCHAR2(1) NULL,
[code]....
and executing below query on those tables-
insert into prod_temp_vendor(vendor_record_seq_no,checksum,rownumber,transaction_type,iu_flag)
select vr.vendor_record_seq_no, tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U' from
prod_vendor_record vr, prod_temp_vendor_record_20000 tvr
where vr.study_seq_no=25707
and vr.control_dataset_seq_no=3910
and vr.key_hash=tvr.key_hash
and dbms_lob.compare(vr.key_col_val, tvr.key_col_val) = 0
and tvr.error_flag is null;
let me know on which columns of PROD_VENDOR_RECORD table to apply index to make processing faster. As I tried to build index like below-
CREATE INDEX idx_prod_vendor_record
ON prod_vendor_record (
study_seq_no,
control_dataset_seq_no,
key_hash
)
/
But it is not being used by above query (see execution plan)
--------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | TQ |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | | | 5168 (100)| | | | |
| 1 | PX COORDINATOR | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10002 | 212 | 445K| 5168 (1)| 00:01:03 | Q1,02 | P->S | QC (RAND) |
[code]....
I have been reading Oracle documentaion about access paths, got strucked at the concept 'Leading columns in index'. what is meant by 'Leading columns of an index', how to find/judge them that they are leading columns.
The url where I am reading is[URL]...
somehow cannot understand why index is not used
in Oracle Database 11g Release 11.2.0.3.0 - 64bit Production
1. Included only indexed column and got a perfect plan
explain plan for2 select s.x_cnt
3 from reported_summary s
4 where s.x_cnt>0;
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 2674489506
-------------------------------------------------------
| Id | Operation | Name | Cost (%CPU)|
-------------------------------------------------------
| 0 | SELECT STATEMENT | | 306 (8)|
|* 1 | INDEX FAST FULL SCAN| S_NUI01 | 306 (8)|
-------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("s"."x_CNT">0)
2. Included some other column and got TABLE ACCESS FULL
explain plan for2 select s.x_cnt,s.ru_id
3 from reported_summary s
4 where s.x_cnt>0;
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 2142873335
---------------------------------------------------------------
| Id | Operation | Name | Cost (%CPU)|
---------------------------------------------------------------
| 0 | SELECT STATEMENT | | 2421 (3)|
|* 1 | TABLE ACCESS FULL| REPORTED_SUMMARY | 2421 (3)|
---------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("s"."x_CNT">0)
3. Included all other columns and got TABLE ACCESS FULL as well explain plan for2 select s.x_cnt,s.* 3 from reported_summary s 4 where s.x_cnt>0;
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 2142873335
---------------------------------------------------------------
| Id | Operation | Name | Cost (%CPU)|
---------------------------------------------------------------
| 0 | SELECT STATEMENT | | 2421 (3)|
|* 1 | TABLE ACCESS FULL| REPORTED_SUMMARY | 2421 (3)|
---------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("s"."x_CNT">0)
1) how to find a primary key of a table in oracle, for example if I want to drop a index in table , how do I find what is the primary key in a table so that I can issue that command.
P/s: I don't have OEM installed so I must use SQL command
Example of dropping the index
ALTER TABLE table_name
drop CONSTRAINT constraint_name;
For example:
ALTER TABLE supplier
drop CONSTRAINT supplier_pk;
What should be the order of columns while creating b-tree non-unique index.
Low cardinality first
or
Hight cardinality first
we have oracle 8i/win nt. (Prod Server running 24 X7)
On doing a explain plan on long running queries. i realized a couple of columns (that were used in the WHERE condition, were not having any indexes.)
More importantly, here we do not have a Test environment.
I would like to know if i can go ahead and create indexes for those 2 columns by issuing
CREATE INDEX index_name on table_name(Column_name);
on our PDB.
Would this be of any impact on our PDB? Do i check anything more prior to building these indexes. or Do have i create them at a down time of PDB.
How to find in the oracle10g database if there is any column which is not being used at all.If the data is there in the column,how to check when was it last populated.
View 3 Replies View Relatedi am trying to find the index want to rebuild or not for that i have analyzed that index after that i don't know how to calculate the ration could any one steps to do calculate the following ratio
Run the ANALYZE INDEX command on the index to validate its structure and then calculate the ratio of LF_BLK_LEN/LF_BLK_LEN+BR_BLK_LEN and if it isn?t near 1.0 (i.e. greater than 0.7 or so) then the index should be rebuilt. Or if the ratio BR_BLK_LEN/ LF_BLK_LEN+BR_BLK_LEN is nearing 0.3.
I need a query to find list all tables in a schema which does not have 'ADDRESS', 'CITY', 'STATE' columns.
View 8 Replies View RelatedI have a table with two columns Column1 and column2
Like such
create table testTable (column1 number(15), column2 number(15));
insert into testTable values (1,5);I need to find the numbers between column 1 and column 2 including the column 1's number and column's 2 number.
so my answer set should be
1,2,3,4,5
How to find which table or Index needs to be reorg..??
IS there any Query!!!.
I have three tables,let's say
table stores
sid | store_name
1 | one
2 | two
3 | three
table products
pid | sid | p_name
1 | 2 | pone
2 | 2 | ptwo
3 | 3 | pthree
table sales
said | sid | pid
1 | 2 | 1
2 | 3 | 1
3 | 2 | 2
4 | 1 | 3
5 | 2 | 2
6 | 3 | 2
7 | 3 | 2
and i want display the product that sells best in every store. I try to group by multiple columns counting how many times each product was sold in every store, but don't know how to select the one which was best sold (maximal number of times)
is there a way to find out which unused columns in oracle?
View 8 Replies View Relatedquery to find out common data from 2 columns in two different tables??
View 6 Replies View RelatedGiven a table with some columns and data associated with that. Need to find out a column or a combination of some columns, so that the values or combination of values will be unique in the table.The table and number of columns and the columns will be dynamic.
View 10 Replies View RelatedHow to find non-indexed queries and columns that require indexes?
View 3 Replies View RelatedQuery
SELECT case.case_objid FROM clrods.case@clrods.equant.com case, table_x_cwp_tickect_details_vw t WHERE CASE.case_condition_cd IN ('OPEN', 'OPEN-DISPATCH', 'OPEN-REJECT', 'OPEN-RETURNED') AND case.case_type_cd in ('CUSTOMER FAULT', 'CHRONIC','SCHEDULED ACTIVITY','PROBLEM') AND ROWNUM <= 500 AND case.case_objid = t.ticket_objid AND ( ( case.account_id = '672286' ) ) ORDER BY case.case_id DESC
From PROD
Plan
SELECT STATEMENT HINT: FIRST_ROWS Cost: 2,629 Bytes: 221,500 Cardinality: 500
37 SORT ORDER BY Cost: 2,629 Bytes: 221,500 Cardinality: 500
36 COUNT STOPKEY
[code]...
From DEV platform
Plan
SELECT STATEMENT HINT: FIRST_ROWS Cost: 591 Bytes: 61,134 Cardinality: 138
37 SORT ORDER BY Cost: 591 Bytes: 61,134 Cardinality: 138
36 COUNT STOPKEY
[code]...
1. Index is rebuild
2. stats are up to date
3. Redef on table is done.
oracle: 10.2.0.5.7...I can get this to work, but not the way the docs seem to say. I am wondering if I am reading the docs wrong or missing something.
The docs seem to say to get a query to run in parallel using an index you use the PARALLEL_INDEX hint. This doesn't seem to work for me. I have to do one of the following
1. change the parallel degree with an alter index, then use the PARALLEL hint (parallel index hint does nothing in this case)
2. use both the parallel_index and parallel hint
Is anyway to create function based index for group function columns.
For example
select max(timestamp),min(age),averge(sal).... ... .. from tab;
I'm a beginner in PL/SQL ! --> " get_sql_metadata(p_query IN Varchar2) RETURN VARCHAR2;" I have to display the names and columns of the query by using the package dbms_sql and how can I know how many columns will have my query.
View 4 Replies View RelatedI have already created large no of indexes on my Database without specifying specific tablespace, now I would like to move all the created indexes into particular tablespace.
View 3 Replies View RelatedI have the below query for which ename column has an index. As of my knowledge below queries 1st and 2st will not use index. Hence i used the 3rd statement and that too its not using the index. Finally i used the 4th query, but even the 4th query is not using the index. Then how do i make this query to use my index??? Do i need to create a function based index for this?
1. select * from emp where ename !='BH' ;
2. select * from emp where ename <> 'BH';
3. select * from emp where ename not in ('BH');
4. select * from emp where ename < 'BH' or ename > 'BH';
is there possible to get those column names on which we have applied dml operations like insert, update,delete if yes,then how .
View 5 Replies View Related