pushing unsupported full outer join to Postgres

Error: DATA_READ ERROR: The JDBC storage plugin failed while trying setup the SQL query.

sql SELECT *
FROM "public"."tjoin1"
FULL JOIN "public"."tjoin2" ON "tjoin1"."c1" < "tjoin2"."c1"
plugin postgres
Fragment 0:0

[Error Id: bc54cf76-f4ff-474c-b3df-fa357bdf0ff8 on centos1:31010]

(org.postgresql.util.PSQLException) ERROR: FULL JOIN is only supported with merge-joinable or hash-joinable join conditions
org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse():2182
org.postgresql.core.v3.QueryExecutorImpl.processResults():1911
org.postgresql.core.v3.QueryExecutorImpl.execute():173
org.postgresql.jdbc.PgStatement.execute():622
org.postgresql.jdbc.PgStatement.executeWithFlags():458
org.postgresql.jdbc.PgStatement.executeQuery():374
org.apache.commons.dbcp.DelegatingStatement.executeQuery():208
org.apache.commons.dbcp.DelegatingStatement.executeQuery():208
org.apache.drill.exec.store.jdbc.JdbcRecordReader.setup():177
org.apache.drill.exec.physical.impl.ScanBatch.<init>():108
org.apache.drill.exec.physical.impl.ScanBatch.<init>():136
org.apache.drill.exec.store.jdbc.JdbcBatchCreator.getBatch():40
org.apache.drill.exec.store.jdbc.JdbcBatchCreator.getBatch():33
org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch():147
org.apache.drill.exec.physical.impl.ImplCreator.getChildren():170
org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch():127
org.apache.drill.exec.physical.impl.ImplCreator.getChildren():170
org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch():127
org.apache.drill.exec.physical.impl.ImplCreator.getChildren():170
org.apache.drill.exec.physical.impl.ImplCreator.getRootExec():101
org.apache.drill.exec.physical.impl.ImplCreator.getExec():79
org.apache.drill.exec.work.fragment.FragmentExecutor.run():230
org.apache.drill.common.SelfCleaningRunnable.run():38
java.util.concurrent.ThreadPoolExecutor.runWorker():1142
java.util.concurrent.ThreadPoolExecutor$Worker.run():617
java.lang.Thread.run():745

SQLState: null
ErrorCode: 0

create table TJOIN1 (RNUM integer not null , C1 integer, C2 integer);
insert into TJOIN1 (RNUM, C1, C2) values ( 0, 10, 15);
insert into TJOIN1 (RNUM, C1, C2) values ( 1, 20, 25);
insert into TJOIN1 (RNUM, C1, C2) values ( 2, NULL, 50);

create table TJOIN2 (RNUM integer not null , C1 integer, C2 char(2));
insert into TJOIN2 (RNUM, C1, C2) values ( 0, 10, 'BB');
insert into TJOIN2 (RNUM, C1, C2) values ( 1, 15, 'DD');
insert into TJOIN2 (RNUM, C1, C2) values ( 2, NULL, 'EE');
insert into TJOIN2 (RNUM, C1, C2) values ( 3, 10, 'FF');