Migrating between versions. Problem with regexp

[Kaloyan Iliev Iliev]

Dear friends,

I have the following problem.

libvar=# select version();
version
----------------------------------------------------------------
PostgreSQL 7.2.3 on i386-pc-bsdi4.0.1, compiled by GCC 2.7.2.1
(1 row)

libvar=# select '\\a\\à\\à\\.' ~ '\\a\\à\\à\\.';
?column?
----------
f
(1 row)
=============== =============== =========

libvar=# select version();

version
--------------------------------------------------------------------------------------------------------------
PostgreSQL 8.0.0beta1 on i686-pc-linux-gnu, compiled by GCC gcc (GCC)
3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk)
(1 row)

libvar=# select '\\a\\à\\à\\.' ~ '\\a\\à\\à\\.';
ERROR: invalid regular expression: invalid escape \ sequence

I am using:
This is perl, v5.6.0 built for i386-bsdos
When I receive a text from CGI I made quotemeta over it to avoid symbols
that may be met in regular expressions.
Then I made DBI->quote over the same string to avoid any sql injection;
The problem is that I use cyrillic and quotemeta put before every
cyrillic character a \.
Then DBI->quote make \ to \\.
And then when I use this string in regular expression in Postgres I
recevie an error in the new version of postgres.
Could anyone sugest solution to my problem.
10x in advance.
Kaloyan

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[Tom Lane]

Kaloyan Iliev Iliev <ne***@faith.di gsys.bg> writes:

libvar=# select '\\a\\à\\à\\.' ~ '\\a\\à\\à\\.';
ERROR: invalid regular expression: invalid escape \ sequence

7.4 and later are stricter about the use of \ than prior versions; see
http://www.postgresql.org/docs/7.4/s...CAPE-SEQUENCES
You could go back to (approximately) the old behavior by changing
regex_flavor to "extended".

regards, tom lane

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[Kaloyan Iliev Iliev]

Thank you
Kaloyan

Tom Lane wrote:

Kaloyan Iliev Iliev <ne***@faith.di gsys.bg> writes:

libvar=# select '\\a\\à\\à\\.' ~ '\\a\\à\\à\\.';
ERROR: invalid regular expression: invalid escape \ sequence

7.4 and later are stricter about the use of \ than prior versions; see
http://www.postgresql.org/docs/7.4/s...CAPE-SEQUENCES
You could go back to (approximately) the old behavior by changing
regex_flavor to "extended".

regards, tom lane

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[Kaloyan Iliev Iliev]

Dear Tom Lane,
I still haven't read all the documentation but I find the following.
If I escape with \\ latin letters it OK, but if escape with \\
cyrillic letters then it is a mistake.

libvar=# select '\\a\ÿ' ~* '\\a\ÿ';
?column?
----------
f
(1 row)

libvar=# select '\\a\\ÿ' ~* '\\a\\ÿ';
ERROR: invalid regular expression: invalid escape \ sequence
libvar=# select '\\a\\ÿ' ~* '\\a\ÿ';
?column?
----------
f
(1 row)

libvar=# select '\\a\ÿ' ~* '\\a\\ÿ';
ERROR: invalid regular expression: invalid escape \ sequence

So I understand that you can't adapt it to all languages and alphabets
but in case this is an error and can be fixed I report it.
Kaloyan

Tom Lane wrote:

Kaloyan Iliev Iliev <ne***@faith.di gsys.bg> writes:

libvar=# select '\\a\\à\\à\\.' ~ '\\a\\à\\à\\.';
ERROR: invalid regular expression: invalid escape \ sequence

7.4 and later are stricter about the use of \ than prior versions; see
http://www.postgresql.org/docs/7.4/s...CAPE-SEQUENCES
You could go back to (approximately) the old behavior by changing
regex_flavor to "extended".

regards, tom lane

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[Tom Lane]

Kaloyan Iliev Iliev <ne***@faith.di gsys.bg> writes:

I still haven't read all the documentation but I find the following.
If I escape with \\ latin letters it OK, but if escape with \\
cyrillic letters then it is a mistake.

No, you're missing the point: there are certain escapes that mean
something, and it rejects the rest. Backslash is not a general-purpose
quoting character.

regards, tom lane

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