Sqlldr direct got ORA-00054: resource busy and acquire with NOWAIT specifie

Question

I have multi-threaded application to kick off multiple sqlldr sessions that will try to insert 200K rows of data into same table from each session. I am using direct path with parallel enabled. The target table has no index, not even a PK, but I got this ORA-00054 error.
Sample control file template:
OPTIONS (SKIP=1, DIRECT=TRUE, PARALLEL=TRUE, SILENT=ALL, MULTITHREADING=TRUE, SKIP_INDEX_MAINTENANCE=TRUE, SKIP_UNUSABLE_INDEXES=TRUE)
UNRECOVERABLE
LOAD DATA
INFILE '&DATA_FILE_NAME'
BADFILE '&BAD_FILE_NAME'
DISCARDFILE '&DISCARD_FILE_NAME'
INTO TABLE TARGET_TABLE
APPEND
FIELDS TERMINATED BY "," OPTIONALLY ENCLOSED BY '"' TRAILING NULLCOLS
( SESSION_ID CONSTANT &SESSION_ID,
FIELD00,
FIELD01,
FIELD02,
FIELD03,
FIELD04,
FIELD05,
FIELD06
The definition of TARGET_TABLE:
CREATE TABLE TARGET_TABLE
SESSION_ID NUMBER(12),
FIELD00 VARCHAR2(4000 BYTE),
FIELD01 VARCHAR2(4000 BYTE),
FIELD02 VARCHAR2(4000 BYTE),
FIELD03 VARCHAR2(4000 BYTE),
FIELD04 VARCHAR2(4000 BYTE),
FIELD05 VARCHAR2(4000 BYTE),
FIELD06 VARCHAR2(4000 BYTE),
FIELD07 VARCHAR2(4000 BYTE),
FIELD08 VARCHAR2(4000 BYTE),
FIELD09 VARCHAR2(4000 BYTE),
FIELD10 VARCHAR2(4000 BYTE),
FIELD11 VARCHAR2(4000 BYTE)
I want to WAIT if there's any race. How can I make it WAIT? Most of the time, WAIT should be the default, but somehow, it acts differently here.
Any help will be highly appreciated.

Answer 1

Looking at the same manual, you can see here that you need exclusive access to the table:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14215/ldr_modes.htm#sthref1449
And here, you can see that if other DML is happening on a table, Oracle says you need to do conventional path load:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14215/ldr_modes.htm#sthref1432
In the case of parallelization, yes, you must set parallel=true. This allows SQL*Loader to manage the parallel inserts. If you were to try to do multiple, concurrent direct path loads yourself by running multiple instances of SQL*Loader, you'd run into the same TM enqueue problem.
The question as to why the TM enqueue is taken in exclusive mode, has to do with how direct path load works. Oracle loads data into previously unformatted, completely empty data blocks from above the HWM. When the load is complete, the HWM is adjusted, and the data is available. Well, Oracle can't allow for multiple concurrent direct loads, all allocating space from above the HWM, and all messing w/ the HWM. This would cause a bit of a problem. And really, you don't want non-direct load DML going on either. So, Oracle disallows it, by taking the TM enqueue in exclusive mode. (Normal DML, non-direct load, takes the TM enqueue in a sharable mode, allowing for other concurrent DML.)
Hope that's clear,
-Mark
Message was edited by:
Mark J. Bobak