[
https://issues.apache.org/jira/browse/OPENJPA-2056?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13120590#comment-13120590
]
Craig Ringer commented on OPENJPA-2056:
---------------------------------------
Note that standard_conforming_strings was introduced in PostgreSQL 8.2. While
this is the oldest release still supported by the PostgreSQL team, and will be
exiting support in December this year, people seem to routinely run old and
unsupported releases. Questions about PostgreSQL 7.4 are not uncommon on the
mailing list. On prior versions, "SHOW standard_conforming_strings" will report
an error.
It's not particularly likely that people running such ancient versions of
PostgreSQL will upgrade OpenJPA, but in an org where DBA/sysadmin is very
separate from dev, or where legacy and actively maintained apps coexist in the
same DBs, it's not impossible. It's worth handling.
I think the escape string syntax E'' was introduced in PostgreSQL 8.1, but
haven't tested to verify that. You should probably not rely on it if people
using ancient versions is a realistic possibility.
The best answer will probably be to always escape strings. Just "SELECT
version()" to decide whether the explicit escape-string syntax should be used,
or if, as older versions that lack standard_conforming_strings, all strings
should be assumed to be subject to escape processing. That makes OpenJPA
independent of the standard_conforming_strings parameter.
It's also important to be aware of the backslash_quote parameter, which is
another compatibility option that can cause pain. Escape single quotes by
doubling them, not by using \', to avoid issues with this. backslash_quote
exists as far back as at least PostgreSQL 7.4, as does support for SQL-standard
'' style quote escapes. If OpenJPA currently escapes quotes using \' this
should be changed to avoid another potential bug.
I know all this is ugly; transitioning toward better standards conformance
often is in cases where no 100%-compatible approach can exist. Unfortunately,
standard_conforming_strings will be a wart for quite a long time and it is a
setting people DO mess with, so it's important to handle it.
> Postgres V9.1 issue with LIKE clause and Escape Strings
> -------------------------------------------------------
>
> Key: OPENJPA-2056
> URL: https://issues.apache.org/jira/browse/OPENJPA-2056
> Project: OpenJPA
> Issue Type: Bug
> Components: jdbc
> Affects Versions: 2.0.0, 2.0.1, 2.1.1
> Environment: Running against a Postgres database at version 9.1
> Reporter: Andrew Hastie
>
> Noticed an issue with the Postgres DBDictionary definition after updating
> Postgres from version 8.4 to 9.1:-
> Here's what you get in the Postgres trace file when executing some JPA driven
> queries where an SQL LIKE is involved:-
> 2011-09-30 14:29:41 BST ERROR: invalid escape string
> 2011-09-30 14:29:41 BST HINT: Escape string must be empty or one character.
> 2011-09-30 14:29:41 BST STATEMENT: SELECT t0.id, t0.identificationMask,
> t0.productName FROM DBTYPE t0 WHERE (t0.identificationMask LIKE $1 ESCAPE
> '\\')
> 2011-09-30 14:29:41 BST ERROR: current transaction is aborted, commands
> ignored until end of transaction block
> This appears to be down to a change the Postgres project have made to escape
> string handling:-
> http://www.postgresql.org/docs/9.1/static/release-9-1.html (see section
> E.2.2.1)
> You appear to be able to override the default DBDictionary setting for this
> as follows to get things working again:-
> <property name="openjpa.jdbc.DBDictionary"
> value="postgres(SearchStringEscape=\)"/>
> So, does this mean OpenJPA needs a version dependent dictionary definition
> for Postgres from now on? Anybody got any better solutions or care to confirm
> what I'm seeing?
> I've also posted this to the Postgres JDBC mailing list in case they have any
> comments.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
