Default ESCAPE Character

[Shelley <ra...@gmail.com>]

OpenJPA appears to use a default ESCAPE character ("/"), which causes
problems when using this character as a String literal in a query.

For example, in the following query:
 SELECT e FROM ENTITY e WHERE e.text LIKE '%\%'

I am searching for the slash "\" character, but OpenJPA converts this to the
following:
 SELECT e0.id, e0.text FROM ENTITY e0 WHERE (CAST(e0.text AS VARCHAR(1000))
LIKE ? ESCAPE '\') [params=(String) %\%]
which actually searches for the percent symbol (%).

When the slash appears elsewhere in a string literal in the query with other
text, even more problems may occur.  For example, the following exception
may occur:
 <openjpa-1.0.1-r420667:592145 nonfatal general error>
org.apache.openjpa.persistence.PersistenceException: Escape character must
be followed by escape character, _, or %. It cannot be followed by any other
character or be at the end of the pattern.

This seems like a bug since the JPA spec states: "The use of Java escape
notation is not supported in query string literals" (4.6.1) and the escape
notation is optionally specified by the user: "string_expression [NOT] LIKE
pattern_value [ESCAPE escape_character]" (4.6.9).

I'm just looking for more thoughts on this before logging a bug, and also
curious as to whether this is configurable or can be overridden in OpenJPA.