We know that rows distribution takes place based on Row hash value of primary index column of the table. Can anyone tell how the distribution of data amongst the fallback amps take place? Also, when the amp is down, how the data is read from the Fallback amp? Basically, please tell as what governs the distribution and access of Fallback data.
Check the manuals on the HashMaps - there exits two. One primary, one for the fallback. The two hashmaps gurantees that the fallback data will be placed on a different cluster.
In case DB detects that an VPROC is down and table is fallback it will use the fallback hashmap to locate the fallback data.