Let me give a brief idea about what we are trying to achieve.
Basically we have three tables
Table1 which has shard key on column linkID. It has 2 other columns postId and personId among many others.
Table2 which has shard key on postId.It does not have linkID.
Table3 which has shard key on column personId. It does not have linkID.
We are trying to join the three tables :
Table1 left join Table2 on postId
Left join Table3 on personId.
All three tables have excess of a 5M records.
Any suggestions on how to improve the join performance?