Hi,
Just noticed something funny with the POSIX Regular expressions and
wondered if it is a bug, or whether I am doing something wrong. I am
using the POSIX RE in a function that is used in several places so would
have to put some nasty if statement in there for this side case if there
is not work around.
=============== =============== =============== =============== ==========
intranet=# select track_id, track_name from ms_track where track_name
like '(%';
track_id | track_name
----------+---------------------------------
1294 | (I Can''t Get No) Satisfaction
1340 | (Hidden Track)
1503 | (Nice Dream)
1942 | (I) Get Lost
(4 rows)
intranet=# select track_name from ms_track where track_name ~ '^\(';
ERROR: invalid regular expression: parentheses () not balanced
intranet=# select track_name from ms_track where track_name ~ '^(';
ERROR: invalid regular expression: parentheses () not balanced
intranet=# select track_name from ms_track where track_name ~ '^\(';
ERROR: invalid regular expression: parentheses () not balanced
=============== =============== =============== =============== ==========
Now I have tried a similar query using the PHP POSIX Regular Expressions
and it accepts the sequence '^\(' and matches correctly. Is this a
"feature" of PG that cannot be worked around easily?
Any thoughts?
Thanks
Nick
P.S. Thanks a lot guys for all the hard work on 8.0, looks good to me.
Lots of really useful features, PITR, Win32, Nested transactions. Good
work guys!
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TIP 8: explain analyze is your friend 5 2717
Nick Barr wrote: Hi,
Just noticed something funny with the POSIX Regular expressions and wondered if it is a bug, or whether I am doing something wrong. I am using the POSIX RE in a function that is used in several places so would have to put some nasty if statement in there for this side case if there is not work around.
=============== =============== =============== =============== ========== intranet=# select track_id, track_name from ms_track where track_name like '(%'; track_id | track_name ----------+--------------------------------- 1294 | (I Can''t Get No) Satisfaction 1340 | (Hidden Track) 1503 | (Nice Dream) 1942 | (I) Get Lost (4 rows)
intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced intranet=# select track_name from ms_track where track_name ~ '^('; ERROR: invalid regular expression: parentheses () not balanced intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced =============== =============== =============== =============== ==========
Now I have tried a similar query using the PHP POSIX Regular Expressions and it accepts the sequence '^\(' and matches correctly. Is this a "feature" of PG that cannot be worked around easily?
Any thoughts?
Thanks
Nick
P.S. Thanks a lot guys for all the hard work on 8.0, looks good to me. Lots of really useful features, PITR, Win32, Nested transactions. Good work guys!
Sorry should of said I am running PG 7.4.3.
Nick
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TIP 4: Don't 'kill -9' the postmaster
Nick Barr <ni***@chuckie. co.uk> writes: intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced
You've forgotten that the string-literal parser will eat one level of
backslashing. You need
intranet=# select track_name from ms_track where track_name ~ '^\\(';
to get that backslash into the regex parser.
regards, tom lane
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On Wed, 2004-08-11 at 14:39, Nick Barr wrote: Hi,
Just noticed something funny with the POSIX Regular expressions and wondered if it is a bug, or whether I am doing something wrong. I am using the POSIX RE in a function that is used in several places so would have to put some nasty if statement in there for this side case if there is not work around.
=============== =============== =============== =============== ========== intranet=# select track_id, track_name from ms_track where track_name like '(%'; track_id | track_name ----------+--------------------------------- 1294 | (I Can''t Get No) Satisfaction 1340 | (Hidden Track) 1503 | (Nice Dream) 1942 | (I) Get Lost (4 rows)
intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced intranet=# select track_name from ms_track where track_name ~ '^('; ERROR: invalid regular expression: parentheses () not balanced intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced =============== =============== =============== =============== ==========
Now I have tried a similar query using the PHP POSIX Regular Expressions and it accepts the sequence '^\(' and matches correctly. Is this a "feature" of PG that cannot be worked around easily?
You need to escape the backslash:
select track_name from ms_track where track_name ~ '^\\
(';
--
Oliver Elphick ol**@lfix.co.uk
Isle of Wight http://www.lfix.co.uk/oliver
GPG: 1024D/A54310EA 92C8 39E7 280E 3631 3F0E 1EC0 5664 7A2F A543 10EA
=============== =============== ==========
"Be still before the LORD and wait patiently for him;
do not fret when men succeed in their ways, when they
carry out their wicked schemes."
Psalms 37:7
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Tom Lane wrote: Nick Barr <ni***@chuckie. co.uk> writes:
intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced
You've forgotten that the string-literal parser will eat one level of backslashing. You need
intranet=# select track_name from ms_track where track_name ~ '^\\(';
to get that backslash into the regex parser.
regards, tom lane
Doh,
Thanks guys.
Nick
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TIP 7: don't forget to increase your free space map settings
On Wed, Aug 11, 2004 at 03:28:17PM +0100, Nick Barr wrote: ============== =============== =============== =============== =========== intranet=# select track_id, track_name from ms_track where track_name like '(%'; track_id | track_name ----------+--------------------------------- 1294 | (I Can''t Get No) Satisfaction 1340 | (Hidden Track) 1503 | (Nice Dream) 1942 | (I) Get Lost (4 rows)
intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced intranet=# select track_name from ms_track where track_name ~ '^('; ERROR: invalid regular expression: parentheses () not balanced intranet=# select track_name from ms_track where track_name ~ '^\('; ERROR: invalid regular expression: parentheses () not balanced ============== =============== =============== =============== ===========
Now I have tried a similar query using the PHP POSIX Regular Expressions and it accepts the sequence '^\(' and matches correctly. Is this a "feature" of PG that cannot be worked around easily?
See the "Regular Expression Details" section of the PostgreSQL manual: http://www.postgresql.org/docs/7.4/s...SYNTAX-DETAILS
The Note under Table 9-12 says, "Remember that the backslash (\)
already has a special meaning in PostgreSQL string literals. To
write a pattern constant that contains a backslash, you must write
two backslashes in the statement."
Try this:
SELECT track_name FROM ms_track WHERE track_name ~ '^\\(';
--
Michael Fuhr http://www.fuhr.org/~mfuhr/
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----
PEP: 324
Title: popen5 - New POSIX process module
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