Using sed to Handle Empty String NULL Values Enclosed in Control Characters
Jim_Knicely
- Select Field - Administrator
You can load data files into a Vertica table using the COPY command. Your data can be delimited by control characters and separated by control characters. Unfortunately, if you also enclose NULL values as an empty string, you might run into a data cast issue.
Example:
dbadmin=> \d test1
List of Fields by Tables
Schema | Table | Column | Type | Size | Default | Not Null | Primary Key | Foreign Key
--------+-------+--------+-----------+------+---------+----------+-------------+-------------
public | test1 | c1 | int | 8 | | f | f |
public | test1 | c2 | timestamp | 8 | | f | f |
public | test1 | c3 | int | 8 | | f | f |
(3 rows)
dbadmin=> \! cat -v /home/dbadmin/test1.csv
^V1^V^G^V2019-03-13 18:55:58.073597^V^G^V1^V
^V2^V^G^V2019-03-13 18:55:58.073597^V^G^V2^V
^V3^V^G^V^V^G^V3^V
^V4^V^G^V2019-03-13 18:55:58.073597^V^G^V4^V
dbadmin=> COPY test1 FROM '/home/dbadmin/test1.csv' DELIMITER e'\x07' ENCLOSED e'\x16' NULL AS '' DIRECT REJECTED DATA TABLE test1_bad;
Rows Loaded
-------------
3
(1 row)
dbadmin=> SELECT * FROM test1;
c1 | c2 | c3
----+----------------------------+----
1 | 2019-03-13 18:55:58.073597 | 1
2 | 2019-03-13 18:55:58.073597 | 2
4 | 2019-03-13 18:55:58.073597 | 4
(3 rows)
dbadmin=> SELECT rejected_reason FROM test1_bad;
rejected_reason
--------------------------------------------------------------------------------------
Invalid timestamp format '' for column 2 (c2).Invalid input syntax for timestamp: ""
(1 row)
One workaround is to clean up the source file using the Linux command sed to replace the enclosed empty string NULL values.
dbadmin=> TRUNCATE TABLE test1;
TRUNCATE TABLE
dbadmin=> \! cat -v /home/dbadmin/test1.csv
^V1^V^G^V2019-03-13 18:55:58.073597^V^G^V1^V
^V2^V^G^V2019-03-13 18:55:58.073597^V^G^V2^V
^V3^V^G^V^V^G^V3^V
^V4^V^G^V2019-03-13 18:55:58.073597^V^G^V4^V
dbadmin=> \! sed -ie "s/^V^V//" /home/dbadmin/test1.csv
dbadmin=> \! cat -v /home/dbadmin/test1.csv
^V1^V^G^V2019-03-13 18:55:58.073597^V^G^V1^V
^V2^V^G^V2019-03-13 18:55:58.073597^V^G^V2^V
^V3^V^G^G^V3^V
^V4^V^G^V2019-03-13 18:55:58.073597^V^G^V4^V
dbadmin=> TRUNCATE TABLE test1;
TRUNCATE TABLE
dbadmin=> COPY test1 FROM '/home/dbadmin/test1.csv' DELIMITER e'\x07' ENCLOSED e'\x16' NULL AS '' DIRECT REJECTED DATA TABLE test1_bad;
Rows Loaded
-------------
4
(1 row)
dbadmin=> SELECT * FROM test1;
c1 | c2 | c3
----+----------------------------+----
1 | 2019-03-13 18:55:58.073597 | 1
2 | 2019-03-13 18:55:58.073597 | 2
3 | | 3
4 | 2019-03-13 18:55:58.073597 | 4
(4 rows)
Helpful Links:
https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/AdministratorsGuide/BulkLoadCOPY/BulkLoadingData.htm
https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/AdministratorsGuide/BulkLoadCOPY/IgnoringColumnsAndFieldsInTheLoadFile.htm
https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/SQLReferenceManual/LanguageElements/Literals/ExtendedStringLiterals.htm
Have fun!