SQL & PL/SQL

Hi All,

I am facing a weird issue in my db,

Q1: SELECT SYSDATE FROM dual@remote_db;

when I issue the above select statement its taking very long time to run (didn't get the output for more than 20mins), but when I modify the query to any of the way below I get the result immediately.

Q2: SELECT /*+ FIRST_ROWS */ SYSDATE FROM dual@remote_db;

or

Q3: SELECT /*+ ALL_ROWS */ SYSDATE FROM dual@remote_db;

or

Q4: SELECT SYSDATE FROM dual@remote_db WHERE rownum <= 1;

I am not able to generate the explain plan for Q1, and the other query goes for a remote db query. Can you help me understand why this is happening this way.

My driving site db version is 10.1.0 and remote site is 11.2.0