pg_locks-exclusivelock for select queries

[arun chirappurath]

Dear all,

I am running below query on a database. why is it creating a exclusive lock
on a virtualxid?  I am running some SELECT queries and its creating an
ExclusiveLock in virtualxid? is this normal?

SELECT datname, pid, state, query, age(clock_timestamp(), query_start) AS
age

FROM pg_stat_activity

WHERE state <> 'idle'

--AND query NOT LIKE '% FROM pg_stat_activity %'

ORDER BY age;

|locktype
|database|relation|page|tuple|virtualxid|transactionid|classid|objid|objsubid|virtualtransaction|pid
 |mode           |granted|fastpath|waitstart|
|----------|--------|--------|----|-----|----------|-------------|-------|-----|--------|------------------|------|---------------|-------|--------|---------|
|relation  |58,007  |12,073  |    |     |          |             |       |
   |        |5/165             |21,912|AccessShareLock|true   |true    |
     |
|virtualxid|        |        |    |     |5/165     |             |       |
   |        |5/165             |21,912|ExclusiveLock  |true   |true    |
     |

Thanks,
ACDBA