如何缩减IPv6地址存储数据？能否截断地址且不丢失唯一性？

Hey there, let's break down your two IPv6 storage questions clearly:

Absolutely, there are practical ways to cut down on storage space for IPv6 addresses, and the most effective ones revolve around how you represent the data:

• Store as raw binary: An IPv6 address is fundamentally 128 bits (16 bytes). If you’re currently storing it as a human-readable string (like the standard colon-separated hex format, which can be up to 39 characters long), switching to binary storage slashes the size drastically—16 bytes vs. 39+ bytes for the string. Most databases and programming languages have native support for binary blob types or fixed-size byte arrays that work perfectly here.
• Use compressed string representation (if you must use strings): If binary storage isn’t feasible for your workflow, use the standard IPv6 compression rules (replacing consecutive zero segments with ::). For example, 2001:0db8:0000:0000:0000:ff00:0042:8329 becomes 2001:db8::ff00:42:8329, which is shorter in string form. This doesn’t save as much space as binary, but it’s better than storing the full uncompressed string.

No, you cannot safely truncate any part of an IPv6 address if you need to maintain uniqueness. Here’s why:

• IPv6 addresses rely on all 128 bits to guarantee uniqueness. Even a single bit difference makes two addresses distinct. For example, two users on the same network might share the same 64-bit prefix (assigned by their ISP), but their 64-bit interface IDs (the latter half) will be unique. Truncating the interface ID part would merge these two distinct addresses into the same stored value, making it impossible to tell them apart.
• Even if you’re dealing with temporary addresses (like privacy extensions), the full 128 bits are still unique per user/device instance. Truncating would erase the identifying part that differentiates one user’s session from another.

If storage space is a concern, go with binary storage instead of truncating—it’s the most efficient way to keep the full unique address without wasting space.

内容的提问来源于stack exchange，提问作者Alew