Parameterized IN clause using multiple columns

Question

I have a query along these lines, where I am trying to filter the result set by comparing tuples (like SQL multiple columns in IN clause):

select *
from mytable
where (key, value) in (values
 ('key1', 'value1'),
 ('key2', 'value2'),
 ...
);

This is valid syntax and works fine on my PostgreSQL 9.3 database.

I want to invoke this query through Spring JDBC where the in value pairs come from a List<Map<String, String>>.

It would be nice to do something like this:

List<Map<String, String>> valuesMap = ...;
String sql = "select * from mytable where (key, value) in (values :valuesMap)";
SqlParameterSource params = new MapSqlParameterSource("valuesMap", valuesMap);
jdbcTemplate.query(sql, params, rowMapper);

When I try this, I get:

org.postgresql.util.PSQLException: No hstore extension installed.
    at org.postgresql.jdbc2.AbstractJdbc2Statement.setMap(AbstractJdbc2Statement.java:1707) ~[postgresql-9.3-1101-jdbc41.jar:na]
    at org.postgresql.jdbc2.AbstractJdbc2Statement.setObject(AbstractJdbc2Statement.java:1910) ~[postgresql-9.3-1101-jdbc41.jar:na]
    at org.postgresql.jdbc3g.AbstractJdbc3gStatement.setObject(AbstractJdbc3gStatement.java:36) ~[postgresql-9.3-1101-jdbc41.jar:na]
    at org.postgresql.jdbc4.AbstractJdbc4Statement.setObject(AbstractJdbc4Statement.java:47) ~[postgresql-9.3-1101-jdbc41.jar:na]
    at org.springframework.jdbc.core.StatementCreatorUtils.setValue(StatementCreatorUtils.java:427) ~[spring-jdbc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.jdbc.core.StatementCreatorUtils.setParameterValueInternal(StatementCreatorUtils.java:235) ~[spring-jdbc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.jdbc.core.StatementCreatorUtils.setParameterValue(StatementCreatorUtils.java:150) ~[spring-jdbc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.jdbc.core.PreparedStatementCreatorFactory$PreparedStatementCreatorImpl.setValues(PreparedStatementCreatorFactory.java:287) ~[spring-jdbc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.jdbc.core.PreparedStatementCreatorFactory$PreparedStatementCreatorImpl.createPreparedStatement(PreparedStatementCreatorFactory.java:244) ~[spring-jdbc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:623) ~[spring-jdbc-4.2.3.RELEASE.jar:4.2.3.RELEASE]

I've looked at the the hstore extension it mentions. It doesn't seem relevant to my problem.

Is there a way to accomplish this without dynamically building the SQL and parameter list?

Answer 1

All you have to do is to pass a list of arrays, where each array contains a key and value, like this:

HashMap<String , String > map = new HashMap<>();
map.put("key0", "value0");
map.put("key1", "value1");
Set<String> keys = map.keySet();
List<String[]> valuesMap = new ArrayList<>();
for(String key:keys){
    String[] entry = {key,map.get(key)};
    valuesMap.add(entry);
}
String sql = "select * from mytable where (key, value) in (values :valuesMap)";
SqlParameterSource params = new MapSqlParameterSource("valuesMap", valuesMap);
jdbcTemplate.query(sql, params, rowMapper);

This is mentioned in the Spring documentation: http://docs.spring.io/spring-framework/docs/current/spring-framework-reference/html/jdbc.html#jdbc-in-clause

Answer 2

Unfortunately, there isn't any easy way to bind a nested collection bind variable to PostgreSQL. You could generate the following SQL string instead

SELECT *
FROM mytable
WHERE (key, value) IN (
  (?, ?),
  (?, ?),
  ...
);

That's a bit of work to keep the SQL string and the variable bindings in sync. You could, however, encode the map as JSON as such:

SELECT *
FROM mytable
WHERE (key, value) IN (
  SELECT 
    t->>'key', 
    t->>'value'
  FROM json_array_elements(?) AS t(v)
)

E.g.

SELECT *
FROM mytable
WHERE (key, value) IN (
  SELECT 
    t->>'key', 
    t->>'value'
  FROM json_array_elements(
    '[{"key":"key1","value":"value1"}, 
      {"key":"key2","value":"value2"}]'
  ) AS t(v)
)

In that case, you would only ever need a single VARCHAR bind variable

Answer 3

If you can't get your solution to work, you could also just concatenate the key and value. Perhaps JDBC has less problems with this more basic syntax:

select *
from mytable
where (key||value) in (
 ('key1value1'),
 ('key2value2'),
 ...
);

For this to work, you'd need to first convert your Java Map to a List with the key and values concatenated as well.