Distinct and Unique

hii,
Is there any difference between distinct and unique in sql...

user644122 wrote:
hii,
Is there any difference between distinct and unique in sql...Read the following blog post
http://mhabib.wordpress.com/2007/03/09/what-is-difference-between-distinct-and-unique/
And check this thread:
Difference between UNIQUE and DISTINCT

Similar Messages

Distinct and Blob

hi everybody,
one question why doesn't work a select statement like:
select distinct asset_id,keyframe from vir_keyframes;
asset_id a number and indicates the blob for further work, the value can be more than one time in the database
keyframe a blob
how am i able to get only records as result where only different asset_id's are displayed.
thanks for helping
tommyO

user644122 wrote:
hii,
Is there any difference between distinct and unique in sql...Read the following blog post
http://mhabib.wordpress.com/2007/03/09/what-is-difference-between-distinct-and-unique/
And check this thread:
Difference between UNIQUE and DISTINCT

Poor performance when Distinct and Order By Used

Hello,
I am getting an slow answer when I add Distinct and Order By to the query:
Without Distinct and Order By lasts 3.57 seconds; without Distinct and Order By lasts 28.15 seconds, which it's too much for our app.
The query is:
select distinct CC.acceso, CC.ext_acceso, TIT.TITULO_SALIDA
from (((Ocurrencias CT01 inner join
palabras p0 on (CT01.cod_palabra = p0.cod_palabra and p0.palabra like 'VENEZUELA%' AND p0.campo = 'AUTOR')) INNER JOIN
CENTRAL CC ON (CT01.ACCESO = CC.ACCESO AND CT01.EXT_ACCESO = CC.EXT_ACCESO))) inner join
codtit ctt on (CC.acceso = ctt.acceso and CC.ext_acceso = ctt.ext_acceso) inner join
titulos tit on (ctt.cod_titulo = tit.cod_titulo and ctt.portada = '1')
where CC.nivel_reg <> 's'
ORDER BY 3 ASC;
The query plan for the query WITH Distinct and Order By is:
Elapsed: 00:00:28.15
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=301 Card=47 Bytes=12220)
1 0 SORT (ORDER BY) (Cost=301 Card=47 Bytes=12220)
2 1 SORT (UNIQUE) (Cost=300 Card=47 Bytes=12220)
3 2 NESTED LOOPS (Cost=299 Card=47 Bytes=12220)
4 3 NESTED LOOPS (Cost=250 Card=49 Bytes=4165)
5 4 NESTED LOOPS (Cost=103 Card=49 Bytes=2989)
6 5 NESTED LOOPS (Cost=5 Card=49 Bytes=1960)
7 6 TABLE ACCESS (BY INDEX ROWID) OF 'PALABRAS' (TABLE) (Cost=3 Card=1 Bytes=19)
8 7 INDEX (RANGE SCAN) OF 'PALABRA' (INDEX (UNIQUE)) (Cost=2 Card=1)
9 6 INDEX (RANGE SCAN) OF 'PK_OCURRENCIAS' (INDEX (UNIQUE)) (Cost=2 Card=140 Bytes=2940)
10 5 TABLE ACCESS (BY INDEX ROWID) OF 'CENTRAL' (TABLE) (Cost=2 Card=1 Bytes=21)
11 10 INDEX (UNIQUE SCAN) OF 'PK_CENTRAL' (INDEX (UNIQUE)) (Cost=1 Card=1)
12 4 TABLE ACCESS (BY INDEX ROWID) OF 'CODTIT' (TABLE) (Cost=3 Card=1 Bytes=24)
13 12 INDEX (RANGE SCAN) OF 'PK_CODTIT' (INDEX (UNIQUE)) (Cost=2 Card=1)
14 3 TABLE ACCESS (BY INDEX ROWID) OF 'TITULOS' (TABLE) (Cost=1 Card=1 Bytes=175)
15 14 INDEX (UNIQUE SCAN) OF 'PK_TITULOS' (INDEX (UNIQUE)) (Cost=0 Card=1)
Statistics
154 recursive calls
0 db block gets
32070 consistent gets
1622 physical reads
0 redo size
305785 bytes sent via SQL*Net to client
2807 bytes received via SQL*Net from client
212 SQL*Net roundtrips to/from client
10 sorts (memory)
0 sorts (disk)
3149 rows processed
The query plan for the query WITHOUT Distinct and Order By is:
Elapsed: 00:00:03.57
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=299 Card=47 Bytes=12220)
1 0 NESTED LOOPS (Cost=299 Card=47 Bytes=12220)
2 1 NESTED LOOPS (Cost=250 Card=49 Bytes=4165)
3 2 NESTED LOOPS (Cost=103 Card=49 Bytes=2989)
4 3 NESTED LOOPS (Cost=5 Card=49 Bytes=1960)
5 4 TABLE ACCESS (BY INDEX ROWID) OF 'PALABRAS' (TABLE) (Cost=3 Card=1 Bytes=19)
6 5 INDEX (RANGE SCAN) OF 'PALABRA' (INDEX (UNIQUE)) (Cost=2 Card=1)
7 4 INDEX (RANGE SCAN) OF 'PK_OCURRENCIAS' (INDEX (UNIQUE)) (Cost=2 Card=140 Bytes=2940)
8 3 TABLE ACCESS (BY INDEX ROWID) OF 'CENTRAL' (TABLE) (Cost=2 Card=1 Bytes=21)
9 8 INDEX (UNIQUE SCAN) OF 'PK_CENTRAL' (INDEX (UNIQUE)) (Cost=1 Card=1)
10 2 TABLE ACCESS (BY INDEX ROWID) OF 'CODTIT' (TABLE) (Cost=3 Card=1 Bytes=24)
11 10 INDEX (RANGE SCAN) OF 'PK_CODTIT' (INDEX (UNIQUE)) (Cost=2 Card=1)
12 1 TABLE ACCESS (BY INDEX ROWID) OF 'TITULOS' (TABLE) (Cost=1 Card=1 Bytes=175)
13 12 INDEX (UNIQUE SCAN) OF 'PK_TITULOS' (INDEX (UNIQUE)) (Cost=0 Card=1)
Statistics
3376 recursive calls
0 db block gets
33443 consistent gets
1061 physical reads
0 redo size
313751 bytes sent via SQL*Net to client
2807 bytes received via SQL*Net from client
422 SQL*Net roundtrips to/from client
90 sorts (memory)
0 sorts (disk)
3149 rows processed
I would appreciate a lot if somebody can tell me how to improve the performance of the query with Distinct and Order By.
Thank you very much,
Icaro Alzuru C.

Hello,
I am getting an slow answer when I add Distinct and Order By to the query:
Without Distinct and Order By lasts 3.57 seconds; without Distinct and Order By lasts 28.15 seconds, which it's too much for our app.
The query is:
select distinct CC.acceso, CC.ext_acceso, TIT.TITULO_SALIDA
from (((Ocurrencias CT01 inner join
palabras p0 on (CT01.cod_palabra = p0.cod_palabra and p0.palabra like 'VENEZUELA%' AND p0.campo = 'AUTOR')) INNER JOIN
CENTRAL CC ON (CT01.ACCESO = CC.ACCESO AND CT01.EXT_ACCESO = CC.EXT_ACCESO))) inner join
codtit ctt on (CC.acceso = ctt.acceso and CC.ext_acceso = ctt.ext_acceso) inner join
titulos tit on (ctt.cod_titulo = tit.cod_titulo and ctt.portada = '1')
where CC.nivel_reg <> 's'
ORDER BY 3 ASC;
The query plan for the query WITH Distinct and Order By is:
Elapsed: 00:00:28.15
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=301 Card=47 Bytes=12220)
1 0 SORT (ORDER BY) (Cost=301 Card=47 Bytes=12220)
2 1 SORT (UNIQUE) (Cost=300 Card=47 Bytes=12220)
3 2 NESTED LOOPS (Cost=299 Card=47 Bytes=12220)
4 3 NESTED LOOPS (Cost=250 Card=49 Bytes=4165)
5 4 NESTED LOOPS (Cost=103 Card=49 Bytes=2989)
6 5 NESTED LOOPS (Cost=5 Card=49 Bytes=1960)
7 6 TABLE ACCESS (BY INDEX ROWID) OF 'PALABRAS' (TABLE) (Cost=3 Card=1 Bytes=19)
8 7 INDEX (RANGE SCAN) OF 'PALABRA' (INDEX (UNIQUE)) (Cost=2 Card=1)
9 6 INDEX (RANGE SCAN) OF 'PK_OCURRENCIAS' (INDEX (UNIQUE)) (Cost=2 Card=140 Bytes=2940)
10 5 TABLE ACCESS (BY INDEX ROWID) OF 'CENTRAL' (TABLE) (Cost=2 Card=1 Bytes=21)
11 10 INDEX (UNIQUE SCAN) OF 'PK_CENTRAL' (INDEX (UNIQUE)) (Cost=1 Card=1)
12 4 TABLE ACCESS (BY INDEX ROWID) OF 'CODTIT' (TABLE) (Cost=3 Card=1 Bytes=24)
13 12 INDEX (RANGE SCAN) OF 'PK_CODTIT' (INDEX (UNIQUE)) (Cost=2 Card=1)
14 3 TABLE ACCESS (BY INDEX ROWID) OF 'TITULOS' (TABLE) (Cost=1 Card=1 Bytes=175)
15 14 INDEX (UNIQUE SCAN) OF 'PK_TITULOS' (INDEX (UNIQUE)) (Cost=0 Card=1)
Statistics
154 recursive calls
0 db block gets
32070 consistent gets
1622 physical reads
0 redo size
305785 bytes sent via SQL*Net to client
2807 bytes received via SQL*Net from client
212 SQL*Net roundtrips to/from client
10 sorts (memory)
0 sorts (disk)
3149 rows processed
The query plan for the query WITHOUT Distinct and Order By is:
Elapsed: 00:00:03.57
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=299 Card=47 Bytes=12220)
1 0 NESTED LOOPS (Cost=299 Card=47 Bytes=12220)
2 1 NESTED LOOPS (Cost=250 Card=49 Bytes=4165)
3 2 NESTED LOOPS (Cost=103 Card=49 Bytes=2989)
4 3 NESTED LOOPS (Cost=5 Card=49 Bytes=1960)
5 4 TABLE ACCESS (BY INDEX ROWID) OF 'PALABRAS' (TABLE) (Cost=3 Card=1 Bytes=19)
6 5 INDEX (RANGE SCAN) OF 'PALABRA' (INDEX (UNIQUE)) (Cost=2 Card=1)
7 4 INDEX (RANGE SCAN) OF 'PK_OCURRENCIAS' (INDEX (UNIQUE)) (Cost=2 Card=140 Bytes=2940)
8 3 TABLE ACCESS (BY INDEX ROWID) OF 'CENTRAL' (TABLE) (Cost=2 Card=1 Bytes=21)
9 8 INDEX (UNIQUE SCAN) OF 'PK_CENTRAL' (INDEX (UNIQUE)) (Cost=1 Card=1)
10 2 TABLE ACCESS (BY INDEX ROWID) OF 'CODTIT' (TABLE) (Cost=3 Card=1 Bytes=24)
11 10 INDEX (RANGE SCAN) OF 'PK_CODTIT' (INDEX (UNIQUE)) (Cost=2 Card=1)
12 1 TABLE ACCESS (BY INDEX ROWID) OF 'TITULOS' (TABLE) (Cost=1 Card=1 Bytes=175)
13 12 INDEX (UNIQUE SCAN) OF 'PK_TITULOS' (INDEX (UNIQUE)) (Cost=0 Card=1)
Statistics
3376 recursive calls
0 db block gets
33443 consistent gets
1061 physical reads
0 redo size
313751 bytes sent via SQL*Net to client
2807 bytes received via SQL*Net from client
422 SQL*Net roundtrips to/from client
90 sorts (memory)
0 sorts (disk)
3149 rows processed
I would appreciate a lot if somebody can tell me how to improve the performance of the query with Distinct and Order By.
Thank you very much,
Icaro Alzuru C.

Using distinct and orderby in the select statment

Hi All,
Can anyone tell me what is the purpose of using distinct and orderby in the select statment.

Hi,
Using the distinct function with more than one column yields some substantial results. SQL will return the rows with distinct or unique combinations of those columns. Assume this same employee table has another column including the salary of each employee. With the use of the distinct function we can pull a list of unique job titles - salaries.
SQL Code:
SELECT DISTINCT job_titles, salary FROM employees;
SQL has returned all the rows with unique combinations of job titles and salaries. Any duplicate combinations of job titles and salaries will be ignored. For example if we had two CEOs in the table making the same salary each year, only one row would be returned but if we had two CEOs with different salaries, both rows would be returned.
Order by
The SQL ORDER BY clause comes in handy when you want to sort your SQL result sets by some column(s). For example if you want to select all the persons from the already familiar Customers table and order the result by date of birth, you will use the following statement:
SELECT * FROM Customers
ORDER BY DOB
As you can see the rows are sorted in ascending order by the DOB column, but what if you want to sort them in descending order? To do that you will have to add the DESC SQL keyword after your SQL ORDER BY clause:
SELECT * FROM Customers
ORDER BY DOB DESC
If you don't specify how to order your rows, alphabetically or reverse, than the result set is ordered alphabetically, hence the following to SQL expressions produce the same result:
SELECT * FROM Customers
ORDER BY DOB
SELECT * FROM Customers
ORDER BY DOB ASC
You can sort your result set by more than one column by specifying those columns in the SQL ORDER BY list. The following SQL expression will order by DOB and LastName:
SELECT * FROM Customers
ORDER BY DOB, LastName
if its useful reward points

Difference b/w index and unique

Hi,
Difference b/w index and unique?

hi,
The optional additions UNIQUE or NON-UNIQUE determine whether the key is to be unique or non-unique, that is, whether the table can accept duplicate entries. If you do not specify UNIQUE or NON-UNIQUE for the key, the table type is generic in this respect. As such, it can only be used for specifying types. When you specify the table type simultaneously, you must note the following restrictions:
You cannot use the UNIQUE addition for standard tables. The system always generates the NON-UNIQUE addition automatically.
You must always specify the UNIQUE option when you create a hashed table.
INDEX:
An index can be considered a copy of a database table that has been reduced to certain fields. This copy is always in sorted form. Sorting provides faster access to the data records of the table, for example using a binary search. The index also contains a pointer to the corresponding record of the actual table so that the fields not contained in the index can also be read.
The primary index is distinguished from the secondary indexes of a table. The primary index contains the key fields of the table and a pointer to the non-key fields of the table. The primary index is created automatically when the table is created in the database
You can also create further indexes on a table in the ABAP Dictionary. These are called secondary indexes. This is necessary if the table is frequently accessed in a way that does not take advantage of the sorting of the primary index for the access.
Indexes speed up data selection from the database. They consist of selected fields of a table, of which a copy is then made in sorted order. If you specify the index fields correctly in a condition in the WHERE or HAVING clause, the system only searches part of the index (index range scan).
The system automatically creates the primary index. It consists of the primary key fields of the database table. This means that for each combination of fields in the index, there is a maximum of one line in the table. This kind of index is also known as UNIQUE.
If you cannot use the primary index to determine the result set because, for example, none of the primary index fields occur in the WHERE or HAVINGclauses, the system searches through the entire table (full table scan). For this case, you can create secondary indexes, which can restrict the number of table entries searched to form the result set.
You create secondary indexes using the ABAP Dictionary. There you can create its columns and define it as UNIQUE. However, you should not create secondary indexes to cover all possible combinations of fields.
Only create one if you select data by fields that are not contained in another index, and the performance is very poor. Furthermore, you should only create secondary indexes for database tables from which you mainly read, since indexes have to be updated each time the database table is changed. As a rule, secondary indexes should not contain more than four fields, and you should not have more than five indexes for a single database table.
If a table has more than five indexes, you run the risk of the optimizer choosing the wrong one for a particular operation. For this reason, you should avoid indexes with overlapping contents.
Secondary indexes should contain columns that you use frequently in a selection, and that are as highly selective as possible. The fewer table entries that can be selected by a certain column, the higher that columns selectivity. Place the most selective fields at the beginning of the index. Your secondary index should be so selective that each index entry corresponds to, at most, five percent of the table entries. If this is not the case, it is not worth creating the index. You should also avoid creating indexes for fields that are not always filled, where their value is initial for most entries in the table.
If all of the columns in the SELECT clause are contained in the index, the system does not have to search the actual table data after reading from the index. If you have a SELECT clause with very few columns, you can improve performance dramatically by including these columns in a secondary index.
What is the difference between primary index and secondary index?
http://help.sap.com/saphelp_47x200/helpdata/en/cf/21eb2d446011d189700000e8322d00/frameset.htm
A difference is made between Primary & Secondary indexes to a table. the primary index consists of the key fields of the table and a pointer to the non-keys-fields of the table. The Primary index is generated automatically when a table is created and is created in the datebase as the same times as the table. It is also possible to define further indexes to a table in the ABAP/4 dictionary, which are then referred to as Secondary indexes.
Message was edited by:
Roja Velagapudi

Diff b/w primary key and unique key?

what is the diff b/w primary key and unique key?

Hi,
With respect to functionality both are same.
But in ABAP we only have Primary key for the Database tables declared in the Data Dictionary.
Unique is generally is the term used with declaring key's for internal tables.
Both primary and Unique keys can identify one record of a table.
Regards,
Sesh

Access path difference between Primary Key and Unique Index

Hi All,
Is there any specific way the oracle optimizer treats Primary key and Unique index differently?
Oracle Version
SQL> select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for IBM/AIX RISC System/6000: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
SQL> Sample test data for Normal Index
SQL> create table t_test_tab(col1 number, col2 number, col3 varchar2(12));
Table created.
SQL> create sequence seq_t_test_tab start with 1 increment by 1 ;
Sequence created.
SQL> insert into t_test_tab select seq_t_test_tab.nextval, round(dbms_random.value(1,999)) , 'B'||round(dbms_random.value(1,50))||'A' from dual connect by level < 100000;
99999 rows created.
SQL> commit;
Commit complete.
SQL> exec dbms_stats.gather_table_stats(USER_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 1565504962
| Id | Operation         | Name       | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |            | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6915 consistent gets
        259 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> create index idx_t_test_tab on t_test_tab(col1);
Index created.
SQL> exec dbms_stats.gather_table_stats('USER_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 1565504962
| Id | Operation         | Name       | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |            | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6915 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> Sample test data when using Primary Key
SQL> create table t_test_tab1(col1 number, col2 number, col3 varchar2(12));
Table created.
SQL> create sequence seq_t_test_tab1 start with 1 increment by 1 ;
Sequence created.
SQL> insert into t_test_tab1 select seq_t_test_tab1.nextval, round(dbms_random.value(1,999)) , 'B'||round(dbms_random.value(1,50))||'A' from dual connect by level < 100000;
99999 rows created.
SQL> commit;
Commit complete.
SQL> exec dbms_stats.gather_table_stats('USER_OWNER','T_TEST_TAB1',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab1;
99999 rows selected.
Execution Plan
Plan hash value: 1727568366
| Id | Operation         | Name        | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |             | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB1 | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6915 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> alter table t_test_tab1 add constraint pk_t_test_tab1 primary key (col1);
Table altered.
SQL> exec dbms_stats.gather_table_stats('USER_OWNER','T_TEST_TAB1',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab1;
99999 rows selected.
Execution Plan
Plan hash value: 2995826579
| Id | Operation            | Name           | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT     |                | 99999 |   488K|    59   (2)| 00:00:01 |
|   1 | INDEX FAST FULL SCAN| PK_T_TEST_TAB1 | 99999 |   488K|    59   (2)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6867 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> If you see here the even though statistics were gathered,
     * In the 1st table T_TEST_TAB, the table is still using FULL table access after creation of index.
     * And in the 2nd table T_TEST_TAB1, table is using PRIMARY KEY as expected.
Any comments ??
Regards,
BPat

Thanks.
Yes, ignored the NOT NULL part.Did a test and now it is working as expected
SQL> create table t_test_tab(col1 number not null, col2 number, col3 varchar2(12));
Table created.
SQL>
create sequence seq_t_test_tab start with 1 increment by 1 ;SQL>
Sequence created.
SQL> insert into t_test_tab select seq_t_test_tab.nextval, round(dbms_random.value(1,999)) , 'B'||round(dbms_random.value(1,50))||'A' from dual connect by level < 100000;
99999 rows created.
SQL> commit;
Commit complete.
SQL> exec dbms_stats.gather_table_stats('GREP_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> set autotrace traceonly
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 1565504962
| Id | Operation         | Name       | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |            | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6912 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> create index idx_t_test_tab on t_test_tab(col1);
Index created.
SQL> exec dbms_stats.gather_table_stats('GREP_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 4115006285
| Id | Operation            | Name           | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT     |                | 99999 |   488K|    63   (2)| 00:00:01 |
|   1 | INDEX FAST FULL SCAN| IDX_T_TEST_TAB | 99999 |   488K|    63   (2)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6881 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL>

Difference between unique constraint and unique index

1. What is the difference between unique constraint and unique index when unique constraint is always indexed ? Which one is better in this case for better performance ?
2. Is Composite index of 3 columns x,y,z better
or having independent/ seperate indexes on 3 columns x,y,z is better for better performance ?
3. It has been very confusing for me to decide which columns to index, I have indexed most foreignkey columns, is it a good idea ? We do lot of selects and DMLS on most of our tables. Is there any query that I can run and find out if indexes are really being used and if they are improving any performance. I have analyzed and computed my indexes using ANALYZE index index_name validate structure and COMPUTE STATISTICS;
null

1. Unique index is part of unique constraint. Of course you can create standalone unique index. But is is no point to skip the logical view of business if you spend same effort to achive.
You create unique const. Oracle create the unique index for you. You may specify index characteristic in unique constraint.
2. Depends. You can't utilize the composite index if the searching condition is not whole or front part of the indexing key. You can't utilize your index if you query the table for y=2. That is.
3. As old words in database arena, Index may be good or bad for a table depending on the size of table, number of columns in the table... etc. It is very environmental dependent. In fact, It is part of database nomalization. Statistic is a way oracle use to determine the execution plan.
Steve
null

Difference between Primary Key and Unique Key with NOT NULL constraint

As both can be referred to another table.
Apart from the difference that Primary Key can be only 1 and Unique keys can be multiple,
is there any difference?
Like in terms of type of Index?

PARAG_C wrote:
As both can be referred to another table.
Apart from the difference that Primary Key can be only 1 and Unique keys can be multiple,
is there any difference?
Like in terms of type of Index?Technically there is almost no difference. Logically the two are often used for slightly different concepts.
The PK (and with it the index) is often an ID column filled by a seqeunce. This key can then be refenced by foreign key constraints on other tables. it is very useful to have this as a meaningless technical construct. Because then the chance that such a ID needs to be changed is extremly slim.
The UK (and with it the index) is often one or several columns that represent the logical key for the entity. Foreign key constriants should not point to this. THe chance that this attribute will be changed at some point in time is way higher then for a meaningless number (ID).

Difference between PRIMARY KEY and UNIQUE KEY with NOT NULL

What is the difference between PRIMARY KEY and UNIQUE KEY with NOT NULL constraint?
Message was edited by:
Nilesh Hole

Answer for the master!!!
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:8743855576462
Thanks,
Karthick

Select distinct and 2 inner joins in same select statement

can anyone guide me how to write the below query for higher performance. can I use for all entires or shall i split this,
please let me know your opinions.
SELECT DISTINCT werks matnr b~stlal idnrk postp d~aennr
   sortf potx1 c~lkenz b~stlty stlst
   INTO TABLE ltab_one
   FROM mast AS a INNER JOIN stko AS b
     ON a~stlnr = b~stlnr
     AND a~stlal = b~stlal
     INNER JOIN stas AS c
     ON b~stlnr = c~stlnr
     AND b~stlal = c~stlal
     AND b~stlty = c~stlty
     INNER JOIN stpo AS d
     ON c~stlnr = d~stlnr
     AND c~stlkn = d~stlkn
     AND c~stlty = d~stlty
WHERE a~werks IN s_werks
     AND ( ( d~andat IN s_datum
        OR d~aedat IN s_datum
        OR a~andat IN s_datum
        OR a~aedat IN s_datum
        OR b~andat IN s_datum
        OR b~aedat IN s_datum
        OR c~andat IN s_datum
        OR c~aedat IN s_datum
        ) AND d~datuv >= lv_effdt )
     AND a~stlan = '1'
     AND matnr IN s_matnr.

WHERE a~werks IN s_werks
     AND ( ( d~andat IN s_datum
        OR d~aedat IN s_datum
        OR a~andat IN s_datum
        OR a~aedat IN s_datum
        OR b~andat IN s_datum
        OR b~aedat IN s_datum
        OR c~andat IN s_datum
        OR c~aedat IN s_datum
        ) AND d~datuv >= lv_effdt )
     AND a~stlan = '1'
     AND matnr IN s_matnr.
This part determines your performance, not the DISTINCT and not the joins.
What is in s_werks, s-datum, s_matnr typically? I guess there are better and worse conditions.

Answers Select clauses: DISTINCT and ORDER BY

When I run an Answers query two things automatically happend:
(1) The DISTINCT clause is added to the Select statement
(2) An ORDER BY is aded to the end.
The DISTINCT appears to be inclusive of all of the columns selected as are all of the columns included in the ORDER BY.
Is there a way that I can setup ANSWERS so that it:
(1) Does not default to add the DISTINCT?
(2) Does not by default include an ORDER BY?
(3) Limit the columsn that the DISTINCT is applied to?
(4) Limit the number of columns in the ORDER BY to only those that I want to sort on?
(5) Is there a way to specify in the OBIEE specific columns that should excluded from the DISTINCT and ORDERE BY?
Thanks...

I wrote a long explanation for this query and the oracle forum preview window decided to eat it, so I'm just posting the query, which might help some people looking for a SELECT DISTINCT approach that retains a sort order and takes the first value for the various grouping columns. In this case, my goal is to get a distinct list of agencies (agname):
select distinct
      first_value(program_category_desc) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname) cat,
      first_value(program_subcategory_desc) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname) sub,
      first_value(progtypename) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname) ptype,
      first_value(agname) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname) ag
    from R_CONCERTS_REPORT
    order by first_value(program_category_desc) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname),
      first_value(program_subcategory_desc) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname),
      first_value(progtypename) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname),
      first_value(agname) over (partition by agname
        order by program_category_desc, program_subcategory_desc, progtypename, agname);

SAP MDM DISPLAY FIELD AND UNIQUE FIELD DIFFERENCE

Hi All
I am new in MDM, can any body please help me understand...
What is the difference between display field and unique field?
Besides to consider one field to be a key in a lookup table, how should we declare that field in the table, as a display field or as an unique field?
It would be helpful if someone kindly explain this to me.
Thanks in advance.
Santanu Ghosh

Hi Santanu,
To explain you the difference in Display field and Unique filed as in MDM in a prescise manner:
Display field:
Every field you create under your main table ie Product atbel will be a displayed field in MDM data manger irrespective of you making it as display or not in Console.
It means two things
1) That this field will be visible in MDM data manger.
2) This field will be visible in Import Manager for Mapping.
But in case of lookup field you need to make the fields as dispaly or not,if you wish to see them in import manger.
If you do not make the fields in a lookup table as dsipaly then even though you can see them in MDM data manger you will not be able to see them in Import amnger as a result not be able to map them.
Unique Field:
When you make any field as unique it maens taht MDM will not allow you to add two values under this field with the same value.
Eg:You acnnot add two materials with material no 100.
Hope it helped
Kindly reward points if found useful
Thanks
Simona

The target element was not found, so all intermediate elements were ignored. As a result, an incorrect element that matches the target element's search properties can be found. Verify that all intermediate elements in Query Id have valid and unique search

Hi All,
I am using CUIT to write automated UI test cases. I have a dialog containing few edit control and buttons.
While running the test it is able to click the button.
However I am getting few warnings as below.
The target element "Technology Name: 'MSAA';Search Configuration: 'VisibleOnly'; Search Properties - ControlType : 'Button',Name : 'OK'" was not found, so all intermediate elements were ignored. As a result, an incorrect element that matches the target
element's search properties can be found. Verify that all intermediate elements in Query Id have valid and unique search properties.
Technology Name: 'MSAA'
Search Configuration: 'VisibleOnly'
Search Properties -
ControlType : 'Button'
Name : 'OK'
Mouse button : 'Left'
I need to resolve these warning. Can anybody suggest me how to resolve these warnings.

Hi sanjay_t,
From these warning message as you provide, I doubt that maybe the button control did not be found successfully by the searchproperties when you playback the Coded UI test.
So I suggest you can try to use DrawHighlight Method to check if the button control
is found before you perform actions on the button target control.
(2)I suggest you can try to use
FindMatchingControls Method on the button control to check if there are more than one control which matches the specified searchproperties and filterproperties.
In addition, as you said that you are using CUIT to write automated UI test. it means that you record the UI action by handing code, am I right?
If yes, I suggest that you can create a simple coded UI test through recording actions using Coded UI Test Builder. Then
generate the code and then try to playback. If playback succeeds, then cross check the properties from UIMap.Designer.cs file. You can reference the code about entering values in the text edit in the UIMap.Designer.cs file to write
your own code.
For more information about how to find a control for coded UI test, I suggest you can refer the following blog.
http://blogs.msdn.com/b/balagans/archive/2009/12/28/9941582.aspx
Best Regards,
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Need duplicate records of ITAB1 into ITAB2 and unique records into ITAB3

HI....
I have one internal table with list of users, i need duplicate users into one internal table and unique users into another internal table..
Unique key to identify users is user mail id....
I dont want to use DELETE ADJACENT statement...
Pls Help
Thanks
Ram

Hi..
Ex: U have ITAB1 - Email is one of the field
1. SORT ITAB1BY EMAIL.
2. DECLARE WF_EMAIL TYPE EMAIL.
LOOP AT ITAB1.
AT FIRST.
WF_EMAIL = ITAB1-EMAIL.
ENDAT.
IF NOT WF_EMAIL = ITAB1-EMAIL.
APPEND ITAB3. " passing unique entry
WF_EMAIL = ITAB1-EMAIL.
ENDIF.
* pass the values to ITAB2 and APPEND for duplicate all records
ENDLOOP.
Hope this Helps,
Nag
Edited by: Naga Mohan Kummara on Dec 14, 2009 11:46 AM

Distinct and Unique

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