Обсуждение: unable to read composite types from CSV files

Hello,

I am initializing tables with data imported/read from CSV files.   This is working well except for those tables that contain composite types.

When attempting to import/read CSV files containing composite data then the error message I get is:  ERROR:  extra data after last expected column.   My questions are a follow:

1)      Can composite types be imported from CSV files?  Or can the CSV file only contain base types (e.g. text, integer, real)?   If composite types CANNNOT be imported from CSV files then please let me know – in this case you can ignore the remainder of this post.

2)      If composite types can indeed be read/imported from CSV files then would you please take a look at the sample code/data provided below and tell me why it generates the error message ‘extra data after last expected column’.   In other words, what am I doing wrong?

BTW, if I remove the parenthesis in the CSV file, read each field separately into a temporary table  then I can successfully copy the contents of the temporary table into the ‘permanent’ table.   However, it would be much more convenient to read composite types directly from the CSV file and avoid working with temporary tables.

I am working with PostgreSQL 10.3 (compiled by Visual C++ build 1800, 64-bit) running under Windows 10 64 bit.  I am using NotePad++ as an editor.   The sample code is run in PSQL.

SQL Test code

The test code I am running in PSQL is as follows:

\! cls

\c postgres;

drop database if exists TestDB;

create database TestDB

    with 

    owner = postgres

    encoding = 'UTF8'

    LC_COLLATE = 'English_United States.1252'

    LC_CTYPE = 'English_United States.1252'

    tablespace = pg_default

    connection limit = -1;

\connect testdb;

create schema Test;

create type Test.MyType as(

           X int,

           Y int,

           Z int

     );

create table Test.A(

     id serial not null primary key,

     MT1 Test.MyType

);

\copy Test.A( MT1 ) from './testComposite.csv' with CSV DELIMITER ',';

Test CSV file contents

The contents of the CSV file (i.e. ‘testComposite.csv’) is:

(1,2,3)

(4,5,6)

(7,8,9)

Error Message

The error message I get is as follows:

psql:testComposite.sql:42: ERROR:  extra data after last expected column

CONTEXT:  COPY a, line 1: "(1, 2, 3)"

Hello David,

Bingo!   I changed the CSV file to the following and it works!

"(1, 2, 3)"

"(4, 5, 6)"

"(7, 8, 9)"

If you don’t mind, could you point out the section in the PostgreSql manual/documentation where this is discussed/explained.  I have repeatedly read section 8.16.6 (i.e. Composite Type Input and Output Syntax) but it does not appear to include this detail.

I spent the whole day struggling with this problem and I am very much relieved that you were able to offer a solution so quickly.   A big thanks!

Ian

From: David G. Johnston [mailto:david.g.johnston@gmail.com]
Sent: 19 April, 2018 20:34
To: ib@ianbellsoftware.com
Cc: pgsql-novice <pgsql-novice@postgresql.org>
Subject: Re: unable to read composite types from CSV files

On Thursday, April 19, 2018, Ian Bell <ib@ianbellsoftware.com> wrote:

2)      If composite types can indeed be read/imported from CSV files then would you please take a look at the sample code/data provided below and tell me why it generates the error message ‘extra data after last expected column’.   In other words, what am I doing wrong?

Test CSV file contents

The contents of the CSV file (i.e. ‘testComposite.csv’) is:

 

(1,2,3)

(4,5,6)

(7,8,9)