Thank you for your reply, AABDULSATTAR. I'm glad that you h***e the same opinion about the ***ilability for searching discussions in these communities. And, thank you for your advice about the choice of the word 'discussions.' I'm not still good at choosing a proper word. It seems that the word 'discussion' can be countable or uncountable depending on a context of describing something. But I'm not sure the difference of contexts to choose a proper word. There are many different topics of conversations or debates in these communities, so it's good to choose the plural form 'discussions.'
By the way, what is the three asterisks? I didn't write the symbols but the system automatically replace the two words - 'h***e' and '***ailability' to 'h***v' and '***ilability', respctively. Are these words gramatically wrong?