From what I can work out, the stats
bytes sent via SQL*Net to client
bytes received via SQL*Net from client
are derived post-compression, because my tests with various levels of compression etc, all return the same values, which match the uncompressed size
What I *can* see is the change in performance - I did the following over a nice crappy wifi connection :-)
Source table - with lots of potential for compression here
SQL create table comp_Test
2 as select rownum x, rpad('x',1000,'x') y from dual
3 connect by level <= 100000;
Table created.
default settings
================
C:\temp>sqlplus scott/tiger@pdb122
SQL*Plus: Release 12.2.0.1.0 Production on Wed Dec 27 13:48:05 2017
Copyright (c) 1982, 2016, Oracle. All rights reserved.
Last Successful login time: Wed Dec 27 2017 13:48:26 +08:00
Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
SQL> set timing on
SQL> set arraysize 1000
SQL> set feedback only
SQL> select * from scott.comp_test;
100000 rows selected.
Elapsed: 00:00:24.68
compression on
================
SQLNET.COMPRESSION=on
SQLNET.COMPRESSION_LEVELS=(low,high)
SQLNET.COMPRESSION_THRESHOLD=1024
(fresh connection)
SQL> set timing on
SQL> set arraysize 1000
SQL> set feedback only
SQL> select * from scott.comp_test;
100000 rows selected.
Elapsed: 00:00:01.93
compression on, larger SDU
================
DEFAULT_SDU_SIZE=1048576
SQLNET.COMPRESSION=on
SQLNET.COMPRESSION_LEVELS=(low,high)
SQLNET.COMPRESSION_THRESHOLD=1024
SQL> set timing on
SQL> set arraysize 1000
SQL> set feedback only
SQL> select * from scott.comp_test;
100000 rows selected.
Elapsed: 00:00:00.98