Investigating Redo - Oracle Database Transactions and Locking Revealed - page 125

Statistics
----------------------------------------------------------
90 recursive calls
123808 db block gets
39407 consistent gets
13847 physical reads
113875056 redo size
1177 bytes sent via SQL*Net to client
1354 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
1000000 rows processed

As you can see, that INSERT generated about 113MB of redo.

■ the example in this section was performed on a NOARCHIVELOG -mode database. If you are in ARCHIVELOG
mode, the table would have to be created or set as NOLOGGING to observe this dramatic change. We will investigate the
NOLOGGING attribute in more detail shortly in the section “Setting nOLOggIng in SQL.” please make sure to coordinate all
nonlogged operations with your dBa on a “real” system.

Note

When we use a direct-path load in a NOARCHIVELOG -mode database, we get the following results:

EODA@ORA12CR1> truncate table t;
Table truncated.

EODA@ORA12CR1> insert /*+ APPEND */ into t
2 select * from big_table;
1000000 rows created.

Statistics
----------------------------------------------------------
551 recursive calls
16645 db block gets
15242 consistent gets
13873 physical reads
220504 redo size
1160 bytes sent via SQL*Net to client
1368 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
86 sorts (memory)
0 sorts (disk)
1000000 rows processed

EODA@ORA12CR1> set autotrace off