BUG #8677: char(n) - bad limit with arrays of composite type

The following bug has been logged on the website:

Bug reference: 8677
Logged by: Fabio Pasqualini
Email address: fabio(dot)pasqualini(at)ac-reims(dot)fr
PostgreSQL version: 8.4.19
Operating system: Debian
Description:

-- test with psql (8.4.19) on debian

create table t1
(
libelle varchar(100),
cp char(5)
);

create table t2
(
id_t2 integer primary key,
nom varchar(100),
tab_t1 t1 array
);

insert into t2(id_t2, nom, tab_t1)
values ( 1,'test1', '{ "(''toto'', ''1'')", "(''titi'', ''1'')"}' );

insert into t2(id_t2, nom, tab_t1)
values ( 2,'test2', '{ "(''toto'', ''12'')", "(''titi'', ''12'')"}' );

insert into t2(id_t2, nom, tab_t1)
values ( 3,'test3', '{ "(''toto'', ''123'')", "(''titi'', ''123'')"}' );

insert into t2(id_t2, nom, tab_t1)
values ( 4,'test4', '{ "(''toto'', ''1234'')", "(''titi'', ''1234'')"}' );

insert into t2(id_t2, nom, tab_t1)
values ( 5,'test5', '{ "(''toto'', ''12345'')", "(''titi'', ''12345'')"}'
);

CREATE TABLE
psql:./enseignement/bts/2014/prog_c++/carnet2/bug/test.sql:14: NOTICE:
CREATE TABLE / PRIMARY KEY créera un index implicite « t2_pkey » pour la
table « t2 »
CREATE TABLE
INSERT 0 1
INSERT 0 1
psql:./enseignement/bts/2014/prog_c++/carnet2/bug/test.sql:25: ERREUR:
valeur trop longue pour le type character(5)
LIGNE 2 : values ( 3,'test3', '{ "(''toto'', ''123'')", "(''titi'', '...
^
psql:./enseignement/bts/2014/prog_c++/carnet2/bug/test.sql:28: ERREUR:
valeur trop longue pour le type character(5)
LIGNE 2 : values ( 4,'test4', '{ "(''toto'', ''1234'')", "(''titi'', ...
^
psql:./enseignement/bts/2014/prog_c++/carnet2/bug/test.sql:31: ERREUR:
valeur trop longue pour le type character(5)
LIGNE 2 : values ( 5,'test5', '{ "(''toto'', ''12345'')", "(''titi'',...

fabio(dot)pasqualini(at)ac-reims(dot)fr writes:
> psql:./enseignement/bts/2014/prog_c++/carnet2/bug/test.sql:25: ERREUR:
> valeur trop longue pour le type character(5)
> LIGNE 2 : values ( 3,'test3', '{ "(''toto'', ''123'')", "(''titi'', '...
> ^

These errors are entirely correct, because you've misunderstood the
(admittedly complicated) quoting requirements for nested arrays/records
in literal values. Extracting the values that you did manage to store
shows the problem:

# select (tab_t1)[1].cp from t2;
cp
-------
'1'
'12'
(2 rows)

The quotes are being taken as data characters, and there's a leading space
in there too.

The rules for writing composite literals are explained here:
http://www.postgresql.org/docs/9.3/static/rowtypes.html#ROWTYPES-IO-SYNTAX

On the whole, it's very often easier to use ARRAY[] and ROW()
constructors than to get the quoting rules right for literal syntax.
I'd have done these examples like this:

insert into t2(id_t2, nom, tab_t1)
values ( 3,'test3',array[row('toto', '123'), row('titi', '123')]::t1[]);

You need an explicit cast unfortunately, because otherwise the ARRAY[]
constructor yields record[] which is not considered automatically
castable to t1[].

regards, tom lane