Hi,
update valley set test='this is a test'
Such query updates ALL of your records in the table.
5 million records * 47 fields - that can be several gigabytes of data.
The system has to scan that gigabytes to change every record. This is a huge
task. Try vacuuming and see if it helps. It can help a lot, if you perform
such 'whole table updates' often.
Best regards,
Piotr Kolaczkowski