Load into oracle table from cobol flat file with occurs times - oracle

Question

Incoming file format mainframe/cobol record layout, one single record that is more than 21000 characters long. Please be aware of the occurs 350 times , which is making the record length very long, a horizontal layout, instead of a row-like layout in incoming file.
id pic x(23).
idnum pic 9(04).
filler pic x(10).
grp occurs 350 times
grpkey1 PIC X(25).
grpkeynum PIC X(09).
grpsubkey PIC X(01).
grptyp PIC X(01).
grpst PIC X(08).
grpend PIC X(08).
filler PIC X(10).
Target Table Definition (Preferably Oracle External Table)
create table grpkeys (
id CHAR(23),
idnum CHAR(04),
filler10 CHAR(10),
grpkey1 CHAR(25),
grpkeynum CHAR(09),
grpsubkey CHAR(01),
grptyp CHAR(01),
grpst CHAR(08),
grpend CHAR(08),
filler20 CHAR(10)
)
I have to load above record format in a file into a table (preferably a working oracle external table, if possible). id, idnum, filler10 values need to be copied into all 350 records created in oracle table (preferably external table) for a single record of incoming file. Please suggest the easiest way to accomplish this.

Answer 1

I'll stick to 5 columns for this example, but there should be no syntactic nor performance restriction to scale from 005 up to 350. Example assumes your file is on Oracle database server in file /tmp/test/test.txt.
My recommendation is to use an Oracle external table definition that effectively reads the data file "as is" (in all its 350-column glory), but does not worry about parsing out the 350-repeat field into components like grpkey1, grpsubkey, etc.
CREATE DIRECTORY TEST_DIR AS '/tmp/test';
CREATE TABLE TEST_XT
(
id VARCHAR2(23),
idnum INTEGER,
filler10 VARCHAR2(10),
GRP_001 varchar2(62),
GRP_002 varchar2(62),
GRP_003 varchar2(62),
GRP_004 varchar2(62),
GRP_005 varchar2(62)
)
ORGANIZATION EXTERNAL
(
TYPE ORACLE_LOADER
DEFAULT DIRECTORY TEST_DIR
ACCESS PARAMETERS
(
RECORDS DELIMITED BY NEWLINE
FIELDS
(
ID CHAR(23),
IDNUM INTEGER EXTERNAL (4),
FILLER10 CHAR(10),
GRP_001 CHAR(62),
GRP_002 CHAR(62),
GRP_003 CHAR(62),
GRP_004 CHAR(62),
GRP_005 CHAR(62)
)
)
LOCATION ('test.txt')
);
Then wrap that external table definition with a view definition that performs an UNPIVOT operation (plus some basic SUBSTR functions to slice each of the 350 unpivoted GRP fields into its constituent pieces).
CREATE OR REPLACE VIEW TEST_V AS
SELECT ID, IDNUM, FILLER10, GRP_NUM,
SUBSTR(GRP_STR,01,25) GRPKEY1,
SUBSTR(GRP_STR,26,09) GRPKEYNUM,
SUBSTR(GRP_STR,35,01) GRPSUBKEY,
SUBSTR(GRP_STR,36,01) GRPTYP,
SUBSTR(GRP_STR,37,08) GRPST,
SUBSTR(GRP_STR,45,08) GRPEND,
SUBSTR(GRP_STR,53,10) FILLER20
FROM
(
SELECT *
FROM TEST_XT
UNPIVOT
(GRP_STR FOR GRP_NUM IN
(
GRP_001 as 1,
GRP_002 as 2,
GRP_003 as 3,
GRP_004 as 4,
GRP_005 as 5
)
)
);
Of course, you can query view directly, or load to standard table (insert into standard_table select * from test_v) for indexing, partitioning, etc needs.
Also, you can scale to desired level of performance by adding parallelism to external table:
ALTER TABLE TEST_XT PARALLEL 8;