SQL schema and unicity on history/history_uint

[dakol]

there is one index on histories tables:

CREATE INDEX history_1 on history (itemid,clock);
CREATE INDEX history_uint_1 on history_uint (itemid,clock);

Question:

Why this index is not unique ?

Is it expected to have more than 1 value for each (itemid, clock) ?

[Alexei]

Is it expected to have more than 1 value for each (itemid, clock) ?

Why not? SNMP traps, for example.

[dakol]

Why not? SNMP traps, for example.

1 item belongs to 1 host, how a host could send 2 values at the same time ?

link up/down ?

perhaps clock might be more precise ? milliseconds ?