KSQLDB REST API: single query returns different results

Question

Dears,

I am newby in case of ksqldb. My simple query executed several times returns different results:

[ksqluser][node1][~/home]$ date && curl -X POST "http://A.B.231.50:8088/query" -H "content-type: application/vnd.ksql.v1+json; charset=utf-8" -d @ksqldb/pr90days_N.json|wc -l
Fri Nov 10 02:37:18 PM CET 2023
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 48915    0 48799  100   116  18568     44  0:00:02  0:00:02 --:--:-- 18613
779
[ksqluser][node1][~/home]$ date && curl -X POST "http://A.B.231.50:8088/query" -H "content-type: application/vnd.ksql.v1+json; charset=utf-8" -d @ksqldb/pr90days_N.json|wc -l
Fri Nov 10 02:37:22 PM CET 2023
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 41202    0 41086  100   116   174k    504 --:--:-- --:--:-- --:--:--  175k
650
[ksqluser][node1][~/home]$ date && curl -X POST "http://A.B.231.50:8088/query" -H "content-type: application/vnd.ksql.v1+json; charset=utf-8" -d @ksqldb/pr90days_N.json|wc -l
Fri Nov 10 02:37:24 PM CET 2023
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 48915    0 48799  100   116   146k    355 --:--:-- --:--:-- --:--:--  146k
779
[ksqluser][node1][~/home]$ date && curl -X POST "http://A.B.231.50:8088/query" -H "content-type: application/vnd.ksql.v1+json; charset=utf-8" -d @ksqldb/pr90days_N.json|wc -l
Fri Nov 10 02:37:25 PM CET 2023
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 37265    0 37149  100   116   149k    479 --:--:-- --:--:-- --:--:--  150k
582
[ksqluser][node1][~/home]$ date && curl -X POST "http://A.B.231.50:8088/query" -H "content-type: application/vnd.ksql.v1+json; charset=utf-8" -d @ksqldb/pr90days_N.json|wc -l
Fri Nov 10 02:37:28 PM CET 2023
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 36707    0 36591  100   116   135k    439 --:--:-- --:--:-- --:--:--  135k
573
[ksqluser][node1][~/home]$ date && curl -X POST "http://A.B.231.50:8088/query" -H "content-type: application/vnd.ksql.v1+json; charset=utf-8" -d @ksqldb/pr90days_N.json|wc -l
Fri Nov 10 02:37:30 PM CET 2023
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 35846    0 35730  100   116   193k    644 --:--:-- --:--:-- --:--:--  195k
559
[ksqluser][node1][~/home]$

I do not have any idea what is the reason these odd results. Do you have any experience with similar problems?

Best Regards, Dan