Обсуждение: Arrays and backslashes

I'm running:

colin=# select version();
                                                           version

---------------------------------------------------------------------------------------------------------------------------
  PostgreSQL 8.1.1 on x86_64-unknown-linux-gnu, compiled by GCC gcc
(GCC) 3.4.4 (Gentoo 3.4.4-r1, ssp-3.4.4-1.0, pie-8.7.8)
(1 row)

My problem is as follows:

given this table:
create table test ( c1 text, c2 text[] );

I am having trouble inserting a value into the array column that
contains a single '\' (no quotes) character.  The following examples are
my attempts to produce a value of 'x\y' (no quotes) in both the regular
text and the text array columns in the test table:

insert into test values ( 'x\\y', array['x\\y']);

  c1  |    c2
-----+----------
  x\y | {"x\\y"}
(1 row)

while:

insert into test  values ( 'x\\y', array['x\y']);

  c1  |    c2
-----+----------
  x\y | {xy}
(1 row)

I also tried:

insert into test values ( 'x\\y', array[$$x\y$$]);

  c1  |    c2
-----+----------
  x\y | {"x\\y"}
(1 row)

and:

insert into test values ( 'x\\y', '{x\y}');

  c1  |    c2
-----+----------
  x\y | {xy}
(1 row)

and:

insert into test values ( 'x\\y', '{x\\y}');

  c1  |  c2
-----+------
  x\y | {xy}
(1 row)

and:

insert into test values ( 'x\\y', '{x\\\\y}');

  c1  |    c2
-----+----------
  x\y | {"x\\y"}
(1 row)

just to be complete, I also tried this:

insert into test values ( 'x\\y', '{x\\\y}');

  c1  |  c2
-----+------
  x\y | {xy}
(1 row)

I found an article that may be releated, but didn't provide much
insight: http://archives.postgresql.org/pgsql-bugs/2001-11/msg00162.php
(at least to me).

Any help that can be offered will be greatly appreciated.  Thanks.

- Colin

Colin DuPlantis <colind@sun.com> writes:
> I am having trouble inserting a value into the array column that
> contains a single '\' (no quotes) character.  The following examples are
> my attempts to produce a value of 'x\y' (no quotes) in both the regular
> text and the text array columns in the test table:

> insert into test values ( 'x\\y', array['x\\y']);

>   c1  |    c2
> -----+----------
>   x\y | {"x\\y"}
> (1 row)

The above is perfectly correct: the actual value in c2[1] is 'x\y'.
Read the docs about array I/O formatting:
http://www.postgresql.org/docs/8.1/static/arrays.html#AEN5716

            regards, tom lane