So this basically defeats the entire performance improvement of UUIDv7. Because anything coming from the user will need to look up a UUIDv4, which means every new row needs to create an extra random UUIDv4 which gets inserted into a second B-tree index, which recreates the very performance problem UUIDv7 is supposedly solving.
In other words, you can only use UUIDv7 for rows that never need to be looked up by any data coming from the user. And maybe that exists sometimes for certain data in JOINs... but it seems like it might be more the exception than the rule, and you never know when an internal ID might need to become an external one in the future.
When using v7, I need some sort of audit that checks in every API contract for the usage of v7 and potential information leakage.
Detecting V7 uuids in the API contract would probably require me to enforce a special key name (uuidv7 & uuid for v4) for easier audit.
Engineers will get this wrong more than once - especially in a mixed team of Jr/sr.
Also, the API contracts will look a bit inconsistent: some resources will get addressed by v7, others by v4. On top, by using v4 on certain resources, I'd leak the information that those resources addressed by v4 will contain sensitive information.
By sticking to v4, I'd have the same identifier for all resources across the API. When needed, I can expose the creation timestamp in the response separately. Audit is much simpler since the fields state explicitly what they will contain.
>> So this basically defeats the entire performance improvement of UUIDv7. Because anything coming from the user will need to look up a UUIDv4, which means every new row needs to create an extra random UUIDv4 which gets inserted into a second B-tree index, which recreates the very performance problem UUIDv7 is supposedly solving.
> This is only really true if leaking the creation time of the record is itself a security concern.
No, as "leaking the creation time" is not a concern when API's return resources having properties representing creation/modification timestamps.
Where exposing predictable identifiers creates a security risk, such as exposing UUIDv7 or serial[0] types used as database primary keys, is it enables attackers to be able to synthesize identifiers which match arbitrary resources much quicker than when random identifiers are employed.
0 - https://www.postgresql.org/docs/current/datatype-numeric.htm...
Primary keys using UUID v7 are (potentially) an HR violation.
https://mikenotthepope.com/primary-keys-using-uuid-v7-are-po...
There was previously an article linked here about recovering access to some bitcoin by feeding all possible timestamps in a date range to the password creation tool they used, and trying all of those passwords.
A UUIDv7 primary key seems to reduce / eliminate those problems.
If there is also an indexed UUIDv4 column for external id, I suspect it would not be used as often as the primary key index so would not cancel out the performance improvements of UUIDv7.
[1] https://www.cybertec-postgresql.com/en/unexpected-downsides-...
Very true, as detailed by the link you kindly provided. Which is why a technique I have found useful is to have both an internal `id` PK `serial`[0] column (never externalized to other processes) and another column with a unique constraint having a UUIDv4 value, such as `external_id`, explicitly for providing identifiers to out-of-process collaborators.
0 - https://www.postgresql.org/docs/current/datatype-numeric.htm...
That doesn't matter because it's the creation of the index entry that matters, not how often it's used for lookup. The lookup cost is the same anyways.
There is no need to put the privacy preserving ID in a database index when you can calculate the mapping on the fly
IMO, a major problem solved by UUIDs is the ability to create IDs on the client-side, hence, they are inherently user-facing. A major reason why this is an important use case for UUIDs is because it allows clients to avoid accidental duplication of records when an insertion fails due to network issues. It provides insertion idempotence.
For example, when the user clicks on a button on a form to insert a record into a database, the client can generate the UUID on the client-side, then attach it to a JSON object, then send the object to the server for insertion; in the meantime, if there is a network issue and it's unclear whether or not the record was inserted, the code can automatically retry (or user can manually retry) and there is no risk of duplication of data if you use the same UUID.
This is impossible to do with auto-incrementing IDs because those are generated by the database in a centralized way so the user cannot know the ID head of time and thus, if there is a network failure while submitting a form, the client cannot automatically know whether or not the record was successfully inserted; if they retry, they may create a duplicate record in the database. There is no way to make the operation idempotent without relying on some kind of fixed ID which has a uniqueness constraint on the database side.
If it does matter for your application, then don't expose it - use an opaque id with something like AEAD, and expose that.
for a specification such as uuid, there is not much to improve upon--just rearranging the bytes and their meanings.
You probably shouldn't / don't need to use v7 for your Users table because the age of your User probably has limted to no bearing on the look up patterns. For example, our Steam and Amazon accounts are pretty old, but we likely still use them.
However, your Orders table is significantly more likely to be looked up based on time, so a v7 makes a lot of sense here.
Now I'd argue the security implications are overblown, but in general tems you might also allow someone to look up a user, i.e. you can view my Steam profile, or maybe my Amazon wishlist. You probably don't need to be looking up another Users Order.
Alternativly, if your building an Enterprise Risk Solution, you could take a view that you don't want people knowing how old the risk is, but most solutions would show you some history and would believe that to be pertinent information.
There will be instances of getting it wrong, but it isn't actually _that_ complicated.
The id would be exposed to users. An integer would expose the number of records in it.
Am I using right guys?
And then having uuidv7 as primary and foreign keys, can give you a performance gain.
I'm sure there might be a middle ground where most of the performance gains remain but the deanonymizing risk is greatly reduced.
Edit: encrypting the value in transit seems a simpler solution really
They're more performant than uuidv7. Why would I still use UIID? Perhaps I would still want uuids because they can be generated in client and because they make incorrect JOINs return no rows.
which is pointless
> What can go wrong with using UUIDv7 Using UUIDv7 is generally discouraged for security when the primary key is exposed to end users in external-facing applications or APIs. The main issue is that UUIDv7 incorporates a 48-bit Unix timestamp as its most significant part, meaning the identifier itself leaks the record's creation time.
> This leakage is primarily a privacy concern. Attackers can use the timing data as metadata for de-anonymization or account correlation, potentially revealing activity patterns or growth rates within an organization. While UUIDv7 still contains random data, relying on the primary key for security is considered a flawed approach. Experts recommend using UUIDv7 only for internal keys and exposing a separate, truly random UUIDv4 as an external identifier.
What experts? For what scenarios specifically? When do they consider time-of-creation to be sensitive?
So then what's the point? How I always did things in the past was use an auto increment big int as the internal primary key, and then use a separate random UUID for the external facing key. I think this recommendation from "experts" is pretty dumb because you get very little benefit using UUIDV7 (beyond some portability improvements) if you're still using a separate internal key.
While I wouldn't use UUIDV7 as a secure token like I would UUIDV4, I don't see anything wrong with using UUIDV7 as externally exposed object keys - you're still going to need permissions checks anyway.
Or where, for some reason, the ID needs to be created before being inserted into the database. Like you're inserting into multiple services at once.
I honestly don't see how.
The "naturally sortable" is a good thing for postgres and for most people who want to use UUID, because there is no sorted distribution buckets where the last bucket always grows when inserting.
I want to see something like HBase or S3 paths when UUIDv7 gets used.
It's no worse for privacy than other UUID variants if the "privacy" you're worried about leaking is the creation time of the UUID.
As for range partitioning, you can of course choose to partition on the hash of the UUIDv7 at the cost of giving up cheaper rights / faster indices. On the other hand, that of course gives up locality which is a common challenge of partitioning schemes. It depends on the end-to-end design of the system but I wouldn't say that UUIDv7 is inherently good or bad or better/worse than other UUID schemes.
I assume there would be some type of index on the timestamp portion & the uuid portion?
wouldn’t that make it better for partitioning since we’d only need to query partitions that match the timestamp portion
- Serial keys leak information about the total number of records and the rate at which records are added. Users/attackers may be able to guess how many records you have in your system (counting the number of users/customers/invoices/etc). This is a subtle issue that needs consideration on a case by case basis. It can be harmless or disastrous depending on your application.
- Serial keys are required to be created by the database. UUIDs can be created anywhere (including your backend or frontend application), which can sometimes simplify logic.
- Because UUIDs can be generated anywhere, sharding is easier.
The obvious downside to UUIDs is that they are slightly slower than serial keys. UUIDv7 improves insert performance at the cost of leaking creation time.
I've found that the data leaked by serial keys is problematic often enough; whereas UUIDs (v4) are almost always fast enough. And migrating a table to UUIDv7 is relatively straightforward if needed.
World’s easiest hack. You’re looking at /customers/3836/bills? What happens if you change that to 4000? They’re a big company. I bet that exists.
Did they put proper security checks EVERYWHERE? Easy to test.
But if you’re at /customers/{big-long-hex-string}/bill the chances of you guessing another valid ID are basically zero.
Yeah it’s security through obscurity. But it’s really good obscurity.
Now, the index on the public IDs would be faster with a uuid7 than a uuid4, but you have a similar info leak risk that the article mentions.
bigserial must by generated by the db
So the common response is sequential ID crawling by bad actors. UUIDs are generally un-guessable and you can throw them into slop DBs like Mongo or storage like S3 as primary identifiers without worrying about permissions or having a clever interested party pwn your whole database. A common case of security through obscurity.
In other words, "don't try this with CRDB".
Or are there any random id generators that can compromise, remain sequential-ish without leaking exact timestamps and global ordering?
For anyone interested:
CREATE FUNCTION uuidv7() RETURNS uuid AS $$ -- Get base random UUID and overlay timestamp select encode( set_bit( set_bit( overlay(uuid_send(gen_random_uuid()) placing substring(int8send((extract(epoch from clock_timestamp())*1000)::bigint) from 3) from 1 for 6), 52, 1), -- Set version bits to 0111 53, 1), 'hex')::uuid; $$ LANGUAGE sql volatile;
I would not call this “generally discouraged” when APIs generally surface a created_at timestamp in their responses. A real life example are Stripe IDs which have similar properties (k-sorted) as UUIDv7: https://brandur.org/nanoglyphs/026-ids#ulids
> While UUIDv7 still contains random data, relying on the primary key for security is considered a flawed approach
The correct way is 1. generate ID on server side, not client side 2. always validate data access permission of all IDs sent from client
Predictable ID is only unsafe if you don't validate data access permission of IDs sent from client. Also, UUIDv7 is much less predictable than auto-increment ID.
But I do agree that having create time in public-facing ID can leak analytical information.
There are wild scenarios you can come up with where you may leak something, but that assumes the information isn't coming over anyway.
"Reveals account creation time" - most APIs return this in API responses by default.
When have you seen just a list of UUIDs and no other more revealing metadata?
Meanwhile what pwns 99% of companies? Phishing.
And the amount of information it leaks is negligible - they might know the oldest and the newest and there’s an infinite gulf in between.
It’s better and more practical than SERIAL or BIGSERIAL in every way - if you need a random/external ID, add a second column. Done.
As others have stated, it completely defeats the performance purpose, if you need to lookup using another ID.
That’s one of the nice properties of v4 uuids: you can make up a primary key of a new entity directly on the client and the database can use it directly. Sure: there is tiny collision risk, but it’s so small, you can get away with mostly ignoring it
With v7 however, such a large chunk of the uuid is based on the time, so I’m not sure whether it’s still safe to ignore collisions in any application, especially when you consider client’s clocks to probably be very inaccurate.
Am I overthinking things here?
With UUIDv7 it's split into:
- 48 bits: Unix timestamp in milliseconds
- 12 bis: Sub-millisecond timestamp fraction for additional ordering
- 62 bits: Random data for uniqueness
- 6 bits: Version and variant identifiers
So >4,600,000,000,000,000,000 IDs per fraction of a millisecond.
And unprecise time on the client doesn't matter, because some are ahead and some behind, vut that doesn't make them more likely to clash.
If you needed to look up say the 100 most recent documents, that would require ~100+ disk seeks at random locations just to look up the index due to the random nature of UUIDv4. If they were sequential or even just semi-sequential that would reduce the number of lookups to just a few, and they would be more likely to be cached since most hits would be to more recent rows. Having it roughly ordered by time would also help with e.g. partitioning. With no partitioning, as the table grows, it'll still have to traverse the B-Tree that has lots of entries from 5 years ago. With partitioning by year or year-month it only has to look at a small subset of that, which could fit easily in memory.
Postgres on the other hand doesn’t do clustered indexing on the PK… if I recall correctly.
On the other hand, if you're basically logging to your database so inserts are like 99% of the load, then it's something to consider.
The platform we operate today is fundamentally different and far more resilient than it was five years ago. We've scaled significantly (recently passing $100M ARR) because we took those early lessons seriously and continue to prioritize reliability.
Now someone should make a UUIDv7 -> ULID adapter lib that 1:1 translates UUIDv7 <-> ULID preserving all the timestamp resolution and randomness bits so we can use the db-level UUIDv7 support to store ULIDs.
uuidv7 (-) and nanoid (_-) have special characters which urlencode to themselves.
none are small enough that you want someone reading them over the phone; but from a character legibility, ulid makes more sense.
