[Hackers]Backend quey plan process

     I've been tracing the data structure in the query plan process for a while. But then I found the data structure manipulation is really so confusing. Could some guy tell me where could I find any guide on how to figure out the process and data structure usage? Is there any good resource helping us read the code? 

     BTW, which email system are you using to send to postgres mailing list? As you can keep the top-answering and maintain the title of your email with [hackers] in front, my gmail can not help on that. For this email, I just add by hand.

    Thank you a lot for your help.

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Best Regards
Huang Qi Victor