PgDatabaseMetaData.getIndexInfo breaks with certain custom operator configuration

[jsyrjala]

Describe the issue
It is possible to break method PgDatabaseMetaData.getIndexInfo() by adding certain custom operators.

This happened with a production database that was running Adobe Campaign product. That product defines a bunch of functions and operators for internal usage.

https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabaseMetaData.java#L2531
https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabaseMetaData.java#L2538

Driver Version?
Tested with 42.2.23, 42.2.12. But I expect the same issue be in wide range of versions.

Java Version?
OpenJDK 11

OS Version?

PostgreSQL Version?
AWS RDS 11.10

To Reproduce
Steps to reproduce the behaviour:

Create an & operator like this:

CREATE OR REPLACE FUNCTION f6(numeric, integer) returns integer as 'BEGIN return $1::integer & $2;END;' language plpgsql immutable;
CREATE OPERATOR & (LEFTARG = numeric, RIGHTARG = integer, PROCEDURE = f6);

call getIndexInfo()

Expected behaviour
It is expected that getIndexInfo() works and returns the data.

This is what happens:
getIndexInfo() creates this kind of SQL query and then executes it.

SELECT     tmp.TABLE_CAT,     tmp.TABLE_SCHEM,     tmp.TABLE_NAME,     tmp.NON_UNIQUE,     tmp.INDEX_QUALIFIER,     tmp.INDEX_NAME,     tmp.TYPE,     tmp.ORDINAL_POSITION,     trim(both '"' from [pg_catalog.pg](http://pg_catalog.pg)_get_indexdef([tmp.CI](http://tmp.CI)_OID, tmp.ORDINAL_POSITION, false)) AS COLUMN_NAME,   CASE [tmp.AM](http://tmp.AM)_NAME     WHEN 'btree' THEN CASE tmp.I_INDOPTION[tmp.ORDINAL_POSITION - 1] & 1       WHEN 1 THEN 'D'       ELSE 'A'     END     ELSE NULL   END AS ASC_OR_DESC,     tmp.CARDINALITY,     tmp.PAGES,     tmp.FILTER_CONDITION FROM (SELECT NULL AS TABLE_CAT, n.nspname AS TABLE_SCHEM,   ct.relname AS TABLE_NAME, NOT i.indisunique AS NON_UNIQUE,   NULL AS INDEX_QUALIFIER, ci.relname AS INDEX_NAME,   CASE i.indisclustered     WHEN true THEN 1    ELSE CASE am.amname       WHEN 'hash' THEN 2      ELSE 3    END   END AS TYPE,   (information_schema._pg_expandarray(i.indkey)).n AS ORDINAL_POSITION,   ci.reltuples AS CARDINALITY,   ci.relpages AS PAGES,   [pg_catalog.pg](http://pg_catalog.pg)_get_expr(i.indpred, i.indrelid) AS FILTER_CONDITION,   ci.oid AS CI_OID,   i.indoption AS I_INDOPTION,   am.amname AS AM_NAME FROM [pg_catalog.pg](http://pg_catalog.pg)_class ct   JOIN [pg_catalog.pg](http://pg_catalog.pg)_namespace n ON (ct.relnamespace = n.oid)   JOIN [pg_catalog.pg](http://pg_catalog.pg)_index i ON (ct.oid = i.indrelid)   JOIN [pg_catalog.pg](http://pg_catalog.pg)_class ci ON (ci.oid = i.indexrelid)   JOIN [pg_catalog.pg](http://pg_catalog.pg)_am am ON (ci.relam = am.oid) WHERE true  AND n.nspname = 'myschema' AND ct.relname = 'mytable' AND i.indisunique ) AS tmp ORDER BY NON_UNIQUE, TYPE, INDEX_NAME, ORDINAL_POSITION

Executing the query fails with this error

ERROR:  operator is not unique: smallint & integer
LINE 1: ...EN CASE tmp.I_INDOPTION[tmp.ORDINAL_POSITION - 1] & 1       ...
                                                             ^
HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.

This is the operator configuration:

select oprname, oprowner, oprcode, t1.typname as left_opr, t2.typname as right_opr, t3.typname as result from pg_operator inner join pg_type t1 on t1.oid = oprleft inner join pg_type t2 on t2.oid = oprright inner join pg_type t3 on t3.oid = oprresult where oprname = '&';
oprname,oprowner,oprcode,left_opr,right_opr,result
"&","1","int2and","int2","int2","int2"
"&","1","int4and","int4","int4","int4"
"&","1","bitand","bit","bit","bit"
"&","1","int8and","int8","int8","int8"
"&","1","varbyte_bitand","varbyte","varbyte","varbyte"

The offending places in the code are these:

https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabaseMetaData.java#L2531
https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabaseMetaData.java#L2538

This kind of code:

tmp.I_INDOPTION[tmp.ORDINAL_POSITION - 1] & 1

A fix is to change it to this:

tmp.I_INDOPTION[tmp.ORDINAL_POSITION - 1] & 1::smallint

Other alternative would be to define some additional operator configuration such that postgres can resolve which operator to use in this case.

[jsyrjala]

I'll make soon a PR to add ::smallint casts to PgDatabaseMetaData.getIndexInfo() queries.

[jsyrjala]

PR against release/42.2 is #2253