Reg. indexes on a table

Question

Hi,
Having too many indexex in a table( like an index on each column in a table), will this have any impact on DML performance?
TIA
Edited by: suma_ys on Jan 20, 2010 2:05 AM

Answer 1

Pavan - a DBA wrote:
i dont think so. sorry cant show you a demo as i dont have a test machine now...Here is small test case:
SQL> select * from v$version ;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE     10.2.0.4.0     Production
TNS for Solaris: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production
SQL> create table t3 (tid int, tdesc varchar2(10) default 'T3') ;
Table created.
SQL> create index t3_idx on t3(tdesc) ;
Index created.
SQL> analyze index t3_idx validate structure ;
Index analyzed.
SQL> select rows_per_key, del_lf_rows from index_stats ;
ROWS_PER_KEY DEL_LF_ROWS
           0           0
SQL> insert into t3 (tid) values (1) ;
1 row created.
SQL> insert into t3 (tid) values (2) ;
1 row created.
SQL> commit ;
Commit complete.
SQL> analyze index t3_idx validate structure ;
Index analyzed.
SQL> select rows_per_key, del_lf_rows from index_stats ;
ROWS_PER_KEY DEL_LF_ROWS
           2           0
SQL> delete from t3 where tid = 1 ;
1 row deleted.
SQL> commit ;
Commit complete.
SQL> analyze index t3_idx validate structure ;
Index analyzed.
SQL> select rows_per_key, del_lf_rows from index_stats ;
ROWS_PER_KEY DEL_LF_ROWS
           2           1