About
Data type Conversion.
In an Oracle Net connection with Java, this task is given to the Two-Task Common (TTC) protocol.
Articles Related
Explicit vs Implicit vs No Conversion
In SqlPlus:
create table tmp_source
(
x varchar2(20)
);
insert into tmp_source (x)
WITH data(r) AS (
SELECT 1.0 r FROM dual
UNION ALL
SELECT r+1 FROM data WHERE r < 10000000
)
SELECT to_char(r) FROM data;
commit;
create table tmp_target
(
x number
);
SET TIMING ON
prompt Implicit Conversion
TIMING START
insert into tmp_target (x) SELECT x FROM tmp_source;
TIMING STOP
prompt Explicit Conversion
TIMING START
insert into tmp_target (x) SELECT to_number(x) FROM tmp_source;
TIMING STOP
prompt No Conversion
TIMING START
insert into tmp_source (x) SELECT x FROM tmp_source;
TIMING STOP
SET TIMING OFF
drop table tmp_source;
drop table tmp_target;
Implicit Conversion
10,000,000 rows inserted.
Elapsed: 00:00:10.942
Explicit Conversion
10,000,000 rows inserted.
Elapsed: 00:00:09.326
No Conversion
10,000,000 rows inserted.
Elapsed: 00:00:07.033