At what stage and under what conditions is data moved or redistributed within a map structure?

In Go, moving or redistributing data within a map structure occurs automatically when necessary, usually when the number of elements increases to maintain access efficiency.

When the number of elements in a map reaches a certain threshold, Go's internal mechanism increases the size of the hash table (rehashing), redistributing keys across new buckets. This happens during insert operations when the load on the map becomes too high.

This process is transparent to the user: when adding new elements, the map may automatically redistribute data to optimize performance.

Example:

m := make(map[int]string)
for i := 0; i < 1000; i++ {
    m[i] = fmt.Sprintf("value%d", i)
}
// When adding a large number of elements, Go may redistribute data inside the map

Thus, redistribution occurs during the insertion of new elements when the current structure becomes inefficient.