How to store both IPv4 or IPv6 in single column in SQL Server?

Question

Should I use binary(16) or varbinary(16)?

I know I can use getAddress() in java.net.InetAddress (Java) or System.Net.IPAddress (C#) to get a byte[] representation of both IPv4 and IPv6, but if I need to insert IPv4 i.e. binary(4) into a binary(16) field in SQL Server, do I need to worry about padding or anything?

score 16 · Accepted Answer · answered Aug 25 '10 at 00:02

16

IF you store a binary(4) in a binary(16) column you'll get back, when you read it, a padded value of length 16. If you want to have dynamic length you must use a varbinary(16). This type retains the length of the data inserted, at the cost of adding extra 2 bytes on-disk (the actual length).

answered Aug 25 '10 at 00:02

Remus Rusanu

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Since I expect majority of the IP will still be in IPv4, I guess varbinary(16) makes sense. – Henry Aug 25 '10 at 00:03
And the cost of creating a variable length field – NullUserException Aug 25 '10 at 00:04
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For the exact cost details see http://msdn.microsoft.com/en-us/library/ms178085.aspx and/or http://sqlskills.com/blogs/paul/post/Inside-the-Storage-Engine-Anatomy-of-a-record.aspx – Remus Rusanu Aug 25 '10 at 00:16
Remus Rusanu, would u use binary(16) or varbinary(16)? – Henry Aug 25 '10 at 07:29

score 8 · Answer 2 · answered Aug 25 '10 at 00:11

8

Use v4-in-v6 address embedding to convert your ipv4 addresses to ipv6 format; then you can treat them all identically.

answered Aug 25 '10 at 00:11

zwol

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wouldn't it be just like binary(4) with 12x zero byte padding in front? – Henry Aug 25 '10 at 01:13
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Presumably you expect some of the entries in this database column to be actual ipv6 addresses. The point of v4-in-v6 embedding is that more of your application code won't have to care about the difference (it can just pretend it has nothing but v6 addresses). – zwol Aug 25 '10 at 01:17

How to store both IPv4 or IPv6 in single column in SQL Server?

2 Answers2