How to override default values with region specific values in terraform for OCI NoSQL table configuration - terraform

Question

I want the below map as to be my default values
```locals {
defaults = {
nosql = {
table1 = {
read_units = 20
write_units = 20
storage_gb = 5
}
table2 = {
read_units = 200
write_units = 200
storage_gb = 2
}
table3 = {
read_units = 10
write_units = 10
storage_gb = 1
}
table4 = {
read_units = 10
write_units = 10
storage_gb = 1
}
table5 = {
read_units = 100
write_units = 200
storage_gb = 1
}
table6 = {
read_units = 10
write_units = 10
storage_gb = 1
}
table7 = {
read_units = 10
write_units = 10
storage_gb = 1
}
table8 = {
read_units = 3000
write_units = 3000
storage_gb = 50
}
table9 = {
read_units = 400
write_units = 400
storage_gb = 5
}
table10 = {
read_units = 960
write_units = 860
storage_gb = 20
}
}
}
}```
And I want the below values map to be used to override in a specific region
us-phoenix-1 = {
table1 = {
read_units = 200
write_units = 200
storage_gb = 50
}
table2 = {
read_units = 2000
write_units = 2000
storage_gb = 2
}
table3 = {
read_units = 100
write_units = 10
storage_gb = 1
}
table4 = {
read_units = 10
write_units = 100
storage_gb = 1
}
table5 = {
read_units = 100
write_units = 200
storage_gb = 1
}
table6 = {
read_units = 100
write_units = 10
storage_gb = 1
}
table7 = {
read_units = 10
write_units = 10
storage_gb = 1
}
table8 = {
read_units = 3000
write_units = 3000
storage_gb = 50
}
table9 = {
read_units = 4000
write_units = 400
storage_gb = 5
}
table10 = {
read_units = 960
write_units = 860
storage_gb = 2
}
}
How to write a script in terraform that should choose a region-specific map if the value exists for a given region else it should choose the default map (first code snippet).
This means I need a terraform script that will choose a map if the map exists for the current region else It has to choose the default map.