Extra metadata in mysql slow query log - meaning of Id?

I'm running MySql5.7 with slow query logging enabled, and the log includes more metadata than is mentioned by the docs; these three lines are printed before each query: # Time: 2025-02-18T14:25:16.286041Z # User@Host: root[root] @ localhost [] Id: 261083 # Query_time: 3.677193 Lock_time: 0.001193 Rows_sent: 1 Rows_examined: 4334365 The docs explain that third line only: > each statement written to the log is preceded by a line that begins with a # character and has these fields (with all fields on a single line): > * Query_time > * Lock_time > * Rows_sent > * Rows_examined Of the other two lines, most of the fields are obvious; but does anybody know what the **Id** field represents? It is different for most of the entries in my slow log, but in some cases there are several which have the same Id.