I currently have collected a dataset of different social media posts for each user with labels assigned to each user. I tried to use LSTM, and BERT for the text classification problem, So for each post, I try to predict the label(for example age). This is not sufficient because you need all of the information contained in the sum of posts to determine the user's age for example. My first thought was to concatenate all of the posts for a single user but since I am currently using BERT which has a maximum sequence length of 512 it wouldn't work. My second idea was to use a text summary and combine them in one vector and hope it doesn't pass the maximum length limit.
Do you have any suggestions for a possible solution? I would assume this problem has been dealt with in the scientific literature and I would be thankful if anyone could point me in the right direction.