Thanks for your reply Ken
I am getting this error in log file
[06-Aug-2018 04:11:32 CST6CDT] Cannot find session record 1ed2e2f37df04ea337825a89faced863 for user 79412, creating new session.
[06-Aug-2018 04:11:41 CST6CDT] Cannot find session record c39a49953707c00f53cddfcd0488e4c7 for user 123071, creating new session.
[06-Aug-2018 04:11:47 CST6CDT] Cannot find session record 40a028e52acd1ce136873828e75bfbd6 for user 97990, creating new session.
[06-Aug-2018 04:13:20 CST6CDT] Cannot find session record bc67287e41d6269840aabc78c44dbd82 for user 117015, creating new session.
[06-Aug-2018 04:14:35 CST6CDT] Cannot find session record 00c47fe08112d04912cb819251b9b0e2 for user 71772, creating new session.
[06-Aug-2018 04:15:03 CST6CDT] Cannot find session record d57d57e3cba6bd2d5effdb6b7973d42e for user 88583, creating new session.
[06-Aug-2018 04:22:50 CST6CDT] Cannot find session record 3ab14c8eaa98b718afddf1214513d075 for user 101763, creating new session.
[06-Aug-2018 04:23:13 CST6CDT] Cannot find session record 827ae0d6903e7a84c0a31c99ed09590f for user 119610, creating new session.
[06-Aug-2018 04:34:32 CST6CDT] Cannot find session record 2e927a07fd7cdfbc046f02a82074d432 for user 92874, creating new session.
[06-Aug-2018 05:02:37 CST6CDT] Cannot find session record 701a9f21c5e60db9164f6645ab051139 for user 71119, creating new session.
[06-Aug-2018 05:38:34 CST6CDT] Cannot find session record a6b7ed23c68491d1d6b8afc29cdb1b9f for user 83472, creating new session.
[06-Aug-2018 05:39:41 CST6CDT] Cannot find session record 534879a791751eef04eba723b8ac0395 for user 99729, creating new session.
[06-Aug-2018 05:45:00 CST6CDT] Cannot find session record a173e34ecab5a8e7b1cc14a5777878a3 for user 111744, creating new session.
[06-Aug-2018 05:51:41 CST6CDT] Cannot find session record 1192916473818869c9895f68364e4da7 for user 99772, creating new session.
[06-Aug-2018 05:56:04 CST6CDT] Cannot find session record b1311a4320f019ccefdc180690fa69ec for user 77260, creating new session.
[06-Aug-2018 06:34:48 CST6CDT] Cannot find session record 809fb80ed2b79907585dc381f2cdecc3 for user 90408, creating new session.
[06-Aug-2018 06:47:15 CST6CDT] Cannot find session record c2820bea83c524114a522d9ffaa8c0ea for user 93322, creating new session.
[06-Aug-2018 07:01:41 CST6CDT] Cannot find session record c6d3e5278ca1879cd530393cb40e9fa8 for user 86000, creating new session.
I have valid over 50k valid users and when their question attempt data in mdl_
question_attempts is 1.1 Gb and in mdl_
question_attempt_steps is 914 MB
I dont want their data to delete