EXCEEDING THRESHOLD LIMIT

Document ID : KB000012481
Last Modified Date : 14/02/2018
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Question:

User received the following warning during an explain:                        

THIS SQL STATEMENT IS EXPLICITLY JOINING 4 TABLES IN THE FOLLOWING FROM...    

YOUR INSTALLATION HAS SET A THRESHOLD OF 2 FOR THE NUMBER OF TABLES THAT MAY BE

EXPLICITLY JOINED TOGETHER IN A SINGLE SQL STATEMENT. EXCEEDING THIS LIMIT    

WILL CAUSE POOR PERFORMANCE. How will exceeding these thresholds cause poor  performance?                                                                  

 

Answer:

Increasing the thresholds will take care of the warning but not of the overhead that multiple join can cause.  There are many factors to take in consideration when joining more tables.   Depending on the size of the tables, the result set of joining 4 small tables  can take less time than joining 3 large tables.