PostgreSQL jsonb, `?` and JDBC

As a workaround to avoid the ? operator, you could create a new operator doing exactly the same.

This is the code of the original operator:

CREATE OPERATOR ?(
  PROCEDURE = jsonb_exists,
  LEFTARG = jsonb,
  RIGHTARG = text,
  RESTRICT = contsel,
  JOIN = contjoinsel);

SELECT '{"a":1, "b":2}'::jsonb ? 'b'; -- true

Use a different name, without any conflicts, like #-# and create a new one:

CREATE OPERATOR #-#(
  PROCEDURE = jsonb_exists,
  LEFTARG = jsonb,
  RIGHTARG = text,
  RESTRICT = contsel,
  JOIN = contjoinsel);

SELECT '{"a":1, "b":2}'::jsonb #-# 'b'; -- true

Use this new operator in your code and it should work.

Check pgAdmin -> pg_catalog -> Operators for all the operators that use a ? in the name.

In JDBC (and standard SQL) the question mark is reserved as a parameter placeholder. Other uses are not allowed.

See Does the JDBC spec prevent '?' from being used as an operator (outside of quotes)? and the discussion on jdbc-spec-discuss.

The current PostgreSQL JDBC driver will transform all occurrences (outside text or comments) of a question mark to a PostgreSQL specific parameter placeholder. I am not sure if the PostgreSQL JDBC project has done anything (like introducing an escape as discussed in the links above) to address this yet. A quick look at the code and documentation suggests they didn't, but I didn't dig too deep.

Addendum: As shown in the answer by bobmarksie, current versions of the PostgreSQL JDBC driver now support escaping the question mark by doubling it (ie: use ?? instead of ?).

I had the same issue a couple of days ago and after some investigation I found this.

https://jdbc.postgresql.org/documentation/head/statement.html

In JDBC, the question mark (?) is the placeholder for the positional parameters of a PreparedStatement. There are, however, a number of PostgreSQL operators that contain a question mark. To keep such question marks in a SQL statement from being interpreted as positional parameters, use two question marks (??) as escape sequence. You can also use this escape sequence in a Statement, but that is not required. Specifically only in a Statement a single (?) can be used as an operator.

Using 2 question marks seemed to work well for me - I was using the following driver (illustrated using maven dependency) ...

    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>9.4-1201-jdbc41</version>
    </dependency>

... and MyBatis for creating the SQL queries and it seemed to work well. Seemed easier / cleaner than creating an PostgreSQL operator.

SQL went from e.g.

select * from user_docs where userTags ?| array['sport','property']

... to ...

select * from user_docs where userTags ??| array['sport','property']

Hopefully this works with your scenario!