Less bytes when transferring table
- From: "Herring Dave - dherri" <Dave.Herring@xxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 2 Apr 2009 12:58:10 -0500
I'll admit up front that I'm not a network guy and still have trouble spelling
TCP. That said, I'm trying to understand how the value in "bytes received via
SQL*Net from dblink" would be less than the size of a table, pulled via a
dblink from another database and server.
I've got a remote database ("remote_db"), that's sitting on Tru64, running
9.2.0.8, with a table (TEST_TABLE1_TB). This table was created with PCTFREE 0,
has no empty blocks, is 19,950 MB in size, has 270,552,077 rows, has an average
row length of 71, 538 extents, and 638,373 blocks (32KB block size for the db).
The destination database is 10.2.0.4 running RHEL 4. The transfer is rather
simple: truncate the local table, then run:
INSERT /*+ APPEND NOPARALLEL(a) */ INTO test_table1_tb AS SELECT * FROM
test_table1_tb@remote_db_dbl;
If I check "bytes received via SQL*Net from dblink", it shows that 8,590 MB was
transferred, which is 43% of the table's size. But this smaller number does
match numbers from /proc/net/dev.
Is there something in Oracle Net that optimizes what is transferred, like doing
some sort of compression?
Any help would be appreciated.
David C. Herring | DBA, Acxiom Automotive
630-944-4762 office | 630-430-5988 cell | 630-944-4989 fax
1501 Opus Pl | Downers Grove, IL, 60515 | U.S.A. | www.acxiom.com
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