2017-02-24 14:58:05.929 2 COMMIT
2017-02-24 14:58:05.932 42 SELECT * FROM INFORMATION_SCHEMA.SYSTEM_TABLES WHERE TRUE AND TABLE_SCHEM IS NULL AND TABLE_NAME LIKE XXX
I am using HSQLDB with hsqldb.sqllog=2 property, however during logs analysis I am not sure what are this "2" and "42" etc. numbers. Are they db session identifiers? I can not find any explanation. Any advices where to look for more details?
Yes, they are session numbers.
You can find those SESSION_ID numbers together with more information about each session in the INFORMATION_SCHEMA.SYSTEM_SESSIONS system table.