How to insert NULL values into a PostgreSQL table - postgresql

Question

I have data in CSV file I am trying to insert into a postgresSQL table using pgloader. The input file is from MS SQL server export, and NULL values are already explicitly cast as NULL.
My pgloader scripts seems to fail for the keywords NULL, noticeably for integer and timestamp fields.
I really don't know what I am missing. Your help will be much appreciated.
I can successfully insert into the table from psql console:
insert into raw.a2
(NUM , F_FILENO , F_FOLIONO , F_DOC_TYPE , F_DOCDATE , F_BATCH , F_BOX , F_BLUCPY , F_ROUTOPOST , F_ROUTOUSR , F_WFCREATE , LINKEDFILE , DATECREATE , USERCREATE , DATEUPDATE , USERUPDATE , MEDIA , PGCOUNT , GROUPNUM , SUBJECT , PRI , F_FILECAT)
values
(
16,'18',3,'Nomination Details',NULL,NULL,NULL,1,NULL,NULL,1,'00000016.TIF','2011-02-08 13:02:11.000','isaac','2012-01-12 08:52:31.000','henrey','Multi',4,1.0,0,'-',NULL
);
INSERT 0 1
file-sample
1,'6',1,'Details',2011-02-22 00:00:00.000,NULL,NULL,1,NULL,NULL,2,'00000001.TIF',2011-02-08 09:42:24.000,'kevin',2011-10-27 09:08:42.000,'james','Multi',1,1.0,0,'-',NULL
2,'6',2,'Bio data',NULL,NULL,NULL,1,NULL,NULL,2,'00000002.TIF',2011-02-08 10:25:11.000,'kevin',2012-11-19 16:20:49.000,'pattie','Multi',4,1.0,0,'-',NULL
4,'10',1,'Details',2011-02-22 00:00:00.000,NULL,NULL,1,NULL,NULL,2,'00000004.TIF',2011-02-08 10:43:38.000,'kevin',2014-07-18 10:46:06.000,'brian','Multi',1,1.0,0,'-',NULL
pgloader commands
pgloader --type csv --with truncate --with "fields optionally enclosed by '''" --with "fields terminated by ','" --set "search_path to 'raw'" - "postgresql://postgres:postgres#localhost/doc_db?a2" < null_test
Table
Table "raw.a2"
Column | Type | Collation | Nullable | Default
-------------+-----------------------------+-----------+----------+---------
num | integer | | not null |
f_fileno | character varying(15) | | |
f_foliono | integer | | |
f_doc_type | character varying(50) | | |
f_docdate | timestamp without time zone | | |
f_batch | integer | | |
f_box | integer | | |
f_blucpy | integer | | |
f_routopost | integer | | |
f_routousr | character varying(49) | | |
f_wfcreate | integer | | |
linkedfile | character varying(255) | | |
datecreate | timestamp without time zone | | |
usercreate | character varying(50) | | |
dateupdate | timestamp without time zone | | |
userupdate | character varying(50) | | |
media | character varying(5) | | |
pgcount | smallint | | |
groupnum | double precision | | |
subject | smallint | | |
pri | character varying(1) | | |
f_filecat | character varying(50) | | |
Indexes:
"a2_pkey" PRIMARY KEY, btree (num)
Output/Error
2019-07-24T05:55:24.231000Z WARNING Target table "\"raw\".\"a2\"" has 1 indexes defined against it.
2019-07-24T05:55:24.237000Z WARNING That could impact loading performance badly.
2019-07-24T05:55:24.237000Z WARNING Consider the option 'drop indexes'.
2019-07-24T05:55:24.460000Z ERROR PostgreSQL ["\"raw\".\"a2\""] Database error 22P02: invalid input syntax for integer: "NULL"
CONTEXT: COPY a2, line 1, column f_batch: "NULL"
2019-07-24T05:55:24.461000Z ERROR PostgreSQL ["\"raw\".\"a2\""] Database error 22007: invalid input syntax for type timestamp: "NULL"
CONTEXT: COPY a2, line 1, column f_docdate: "NULL"

Answer 1

From the docs of pgloader:
null if
This option takes an argument which is either the keyword blanks or a
double-quoted string.
When blanks is used and the field value that is read contains only
space characters, then it’s automatically converted to an SQL NULL
value.
When a double-quoted string is used and that string is read as the
field value, then the field value is automatically converted to an SQL
NULL value.
Looks like you're missing --with 'null if "NULL"' in your command.
Otherwise, you should be able to load the CSV data directly from psql:
\copy raw.a2 (NUM, F_FILENO, F_FOLIONO, F_DOC_TYPE, F_DOCDATE, F_BATCH, F_BOX, F_BLUCPY, F_ROUTOPOST, F_ROUTOUSR, F_WFCREATE, LINKEDFILE, DATECREATE, USERCREATE, DATEUPDATE, USERUPDATE, MEDIA, PGCOUNT, GROUPNUM, SUBJECT, PRI, F_FILECAT) FROM 'file.csv' WITH (FORMAT csv, NULL 'NULL')