MySQL uses or to query SQL, and SQL execution is very slow

  When the company makes a one-stop service hall , The interface returns slowly due to data reasons . An interface returns to 90S; 

According to the interface analysis , Found the program executing SQL I found some more data executing SQL Time is slow , One SQL It takes time to run 30S about .

SELECT DISTINCT
    t.id AS appId,
    t.priority
FROM
    yzs_unified_app t
LEFT JOIN yzs_unified_app_theme t1 ON t.id = t1.app_id
LEFT JOIN yzs_app_unified_role t2 ON t.id = t2.app_id
LEFT JOIN yzs_user_unified_role t3 ON t2.role_id = t3.role_id
LEFT JOIN yzs_app_unified_dept_post t4 ON t.id = t4.app_id
LEFT JOIN yzs_user_unified_dept_post t5 ON t4.dept_post_id = t5.dept_post_id
WHERE
 (
  t3.user_id = '1185405911867326464'   or    t5.dept_post_id = -2    
)
and t1.theme_id = 5

t3 The table data has 1W Number of multiple , T5 Yes 100 Multiple data ;

When SQL

  t5.dept_post_id = -2      or  t3.user_id = '1185405911867326464' 

  After replacing the above conditions, I found that soon

Our analysis found that T3 The filtered data exists in the table at Don't appear very slowly , Each piece of data needs to be traversed 1W Number of pieces ; 

solve the problem ：

stay On Filter data conditionally ,

SELECT DISTINCT
    t.id AS appId,
    t.priority
FROM
    yzs_unified_app t
LEFT JOIN yzs_unified_app_theme t1 ON t.id = t1.app_id
LEFT JOIN yzs_app_unified_role t2 ON t.id = t2.app_id
LEFT JOIN yzs_user_unified_role t3 ON t2.role_id = t3.role_id and   t3.user_id = '1185405911867326464' 
LEFT JOIN yzs_app_unified_dept_post t4 ON t.id = t4.app_id
LEFT JOIN yzs_user_unified_dept_post t5 ON t4.dept_post_id = t5.dept_post_id and  t5.dept_post_id = -2    
WHERE
t1.theme_id = 5

Or subquery ：

.............................