How Can I Safely Convert uint64 Hash Values to int64 for PostgreSQL Storage?

Handling Integer Overflow for PostgreSQL Storage

This programming question concerns the conversion of hash function values from uint64 to int64, with a specific focus on PostgreSQL compatibility. PostgreSQL supports BIGINT (signed 64 bits), while the hash function murmur2 returns uint64 values. The programmer desires to efficiently convert these values for storage without affecting their binary representation.

On-purpose Integer Overflow: A Solution

To achieve the conversion without losing data, a type conversion can be utilized. The following code snippet demonstrates this conversion:

i := uint64(0xffffffffffffffff)
i2 := int64(i)
fmt.Println(i, i2)

This approach does not alter the memory representation of the value but changes its type.

Pitfalls in Constant Conversion

Note that attempting to convert an untyped integer constant directly to int64 may lead to compile-time errors. Untyped integer constants with arbitrary precision cannot be directly assigned to int64 if they exceed its maximum value (0x7fffffffffffffff).

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