How to create a pagination with the output of the number of duplicates? - spring

Question

I have a db that stores an archive of messages, my goal is to get the username and the number of messages that match a certain pattern, then page it all out in the browser. The table has just under 2 million rows and will keep getting bigger. The problem is that the output of the number of messages is incorrect and it corresponds (as I understand it) to the size #PageableDefault. I currently use Pageable.unpaged() to work around the problem. Is there a way to load a limited number of users per page, but all the posts associated with them? This would help speed up the loading of the final table.
Archive Entity:
#Entity
#AllArgsConstructor
#NoArgsConstructor
public class Archive {
private String username;
private String txt;
private long id;
private Timestamp createdAt;
#Basic
#Column(name = "username", nullable = false, length = 191)
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
#Basic
#Column(name = "txt", nullable = true, length = -1)
public String getTxt() {
return txt;
}
public void setTxt(String txt) {
this.txt = txt;
}
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Basic
#Column(name = "id", nullable = false)
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
#Basic
#Column(name = "created_at", nullable = false)
#DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
public Timestamp getCreatedAt() {
return createdAt;
}
public void setCreatedAt(Timestamp createdAt) {
this.createdAt = createdAt;
}
Repo:
Page<Archive> findByUsernameContainsAndCreatedAtGreaterThanEqualAndCreatedAtLessThanEqualAndTxt(String username, Timestamp createdAt, Timestamp createdAt2, String txt, Pageable pageable);
Service:
public Page<Report> getOrgData(String username, Timestamp from, Timestamp to, Status status, #PageableDefault(size = 15) Pageable pageable) {
pageable = Pageable.unpaged();
String statusString = getStatusString(status);
Page<Archive> find = repo.findByUsernameContainsAndCreatedAtGreaterThanEqualAndCreatedAtLessThanEqualAndTxt(
username,
from,
to,
statusString,
pageable
);
return getReport(find);
Formation of the final table:
public Page<Report> getReport(Page<Archive> archive) {
LinkedHashMap<String, Long> resultMap = new LinkedHashMap<>();
List<Report> report = new ArrayList<>();
archive.forEach(a -> resultMap.put(a.getUsername(), resultMap.getOrDefault(a.getUsername(), 0L) + 1L));
resultMap.forEach((key, value) -> report.add(new Report(key, value)));
return new PageImpl<>(report);
}