in src/libs/zbxdbcache/nextchecks.c function DCflush_nextchecks exists code:

/* dealing with events */
if (events_num > 0)
events_maxid = DBget_maxid_num("events", "eventid", events_num);

for (i = 0; i < events_num; i++)
{
zbx_snprintf_alloc(&sql, &sql_allocated, &sql_offset, 256,
"insert into events (eventid,source,object,objectid,clock,value) "
"values (" ZBX_FS_UI64 ",%d,%d," ZBX_FS_UI64 ",%d,%d);\n",
events_maxid,
EVENT_SOURCE_TRIGGERS,
EVENT_OBJECT_TRIGGER,
events[i].objectid,
events[i].clock,
TRIGGER_VALUE_UNKNOWN);
events_maxid++;

DBget_maxid_num execute once, but events_maxid may increase, but in ids table max for eventid remains unchanged.

i don't know it's normal or not(