The New ID To Replace GUIDs and Integers in .NET

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Hello, everybody. I'm Nick, and in this video, I will show you a new type of ID being added in .NET 9, which solves the biggest problem of using GUIDs or UUIDs in databases as primary keys.
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#csharp #dotnet

[@user-zp3th3tj8k]

That one guy on your team: Mmm yes. Starting to prep for the Y10K problem now. 😏

[@Kingside88]

Yeah and makeing big panic to PM

[@NickSteffen]

@@Kingside88 lmao, I still remember a product I worked on where they decided to use 4 characters followed by 9 numerals incrementing server names (after an app name) just in case we had a lot of servers. We never had more than 100 sites with the naming scheme and since the names were unique to each site the number was never incremented more than 4. Meanwhile 30 poor technicians had to type all 13 numbers in tens of of thousands of times while they were working on this product. That naming scheme is long dead now, and will never reach the billions of servers that 9 digits would accommodate.

[@memoryleakerz]

You're joking but there's a project manager out there, who's grand grand grand children will be running that stand up meeting on GUIDv7 being about to overflow next year and allocating budget for ir

[@NickAskew]

I'm old enough to remember people who thought 2000 was a long way off 🙂. But I seriously don't think we would need to panic about 8000 years from now.

[@Jallenbah]

A nice little bonus of this implementation is if you do happen to have a table which doesn't store creation time information, or if some issue results in that field being overwritten or not written, you can reverse engineer the Id to find the record creation time.

[@SmoothNanners]

Another point to note is, for some types of data, if you're exposing IDs, you may not want the creation time to be exposed for security reasons.

[@krajekdev]

@@SmoothNanners Thanks, great comment.

[@Kitulous]

and it means that everyone else can as well

[@garage30rc]

I always feel slightly guilty when I create a new GUID and don't persist it in a database or use it in a test. In the whole vastness of eternity, that GUID only had a miniscule chance at existing, and I discarded after just a few milliseconds.

[@z0nx]

Only to be experienced by you, man of stardust

[@T___Brown]

Lol

[@markparker6499]

😂

[@stefan-d.grigorescu]

Hm. Didn't thought that way. I just like to run my console app that prints new guids in a while loop and watch them go out of screen view.

[@ImmoLandwerth]

It’s as if millions of GUIDs cried out in terror and were suddenly discarded.

[@BillyBraga]

6:25 "And I will also be dead" 🤣

[@marcelagraz5915]

😂

[@da3dsoul]

I really feel for the first developer to say that throughout their early 20s and ends up living 10000 years to see the fallout of whatever fallacy they reference. Then again, MS doesn't even want to support Windows 10...

[@knifekitty_ls]

that actually solves a lot of problems

[@ab1ray]

I came to the comments as soon as I heard this 😂

[@GiovanniOrlandoi7]

So glad this new option still maps to the guid type. Thanks for the video!

[@yannolaf]

We use GUID (v4) as the primary key and a generic (auto inc) as the clustered index as a workaround against clustered index fragmentation. Not perfect, but it works ;)

[@lucaswhite12]

LOL I was using this more than 10 years ago! To be clear, the ids were generated on the DB side, and it was a SQL function that did exactly this, generated a new GUID and overwrote part of it with the timestamp so they would be ordered.

[@levmatta]

Me too, but this is better than a custom solution.

[@zhaltys]

Cool

[@pilotboba]

@@levmatta There are some systems where you need to generate an id on the client. Or at least it is much more efficient or eliminates the need to temp id's on client side.

[@lucaswhite12]

​@@pilotbobaOh, definitely! It's a good thing! I just find it a bit amusing how some things "persist" 🤭 in our dev world!

[@Spylak]

Hello Nick, a comparison video with ULID would be interesting I think.

[@MoehreMoe100]

ULID just has a few more bytes of randomness because it doesn't have to specify a version

[@antonmartyniuk]

Nick forgot to put an Easter Egg Console.WriteLine in the Program.cs

[@nickchapsas]

I knew I missed something!

[@SlyEcho]

I don’t think this is compatible with how SQL Server stores unique identifiers. They are ordered by the byte array part first if I remember correctly.

[@bfrytech]

It's not. A lot of these going around.

[@ivancavlek4755]

Unfortunately, this does not help with SQL Server (what .NET developers need the most) as SQL Server orders its uniqueidentifiers indexes at the end instead of at the beginning as this beautiful function does 😋.

[@gunnarliljas8459]

Exactly.

[@endomorfine]

you can reverse result value and it will help actually

[@TheCzemike]

This just reinforces my belief that auto-incrementing integers are the best for primary keys; anything else is just a candidate for being another means of unique value lookup.

[@Steven-ch2wm]

On top of that, it is super easy to defragment the indexes on your relational database (or at least, it is with Microsoft SQL Server). I don't understand why nobody is talking about that in the comments. With SQL Server you can call DBCC DBREINDEX ('{table name}', {index name}); to defragment an index. In our databases we have a scheduled script that runs once a week at off peak hours that checks which indexes require defragmentation and reindex them when they are above a certain threshold.

[@md.redwanhossain6288]

don't use sql server, use postgres.

[@KritX01]

I've been using ULID since it's also time based

[@xlerb2286]

Being able to order by creation date/time solves my biggest gripe about Guids. Too bad I'm retired now and hopefully will never need to create another unique id ;)

[@cwevers]

Doesn't this eat into the randomness/uniqueness? Since they are both the same length, adding a potentially overlapping part (the time).

[@SilasPeters]

I also wonder what the chances are now

[@nick21087]

Well a collision could now ONLY occur within the same ms? So chance of collision is probably less overall?

[@VladSandu79]

What about brute forcing ? I feel like there are fewer posible results now, for each ms

[@OhhCrapGuy]

Considering that there are still 74 bits of entropy every millisecond, and that a GUID from one millisecond can never collide with a GUID from another millisecond, there are advantages to this GUID compared to old style ones. And the most important one is that your "risk" of collision resets all the way to zero every millisecond. You could generate 1000 GUIDs a second at a constant rate of 1 per ms for 700 years, and have 100% certainty that there would never be a duplicate GUID. Now, if you're inserting more than one a millisecond, the risk of collision per millisecond is the birthday paradox problem, with the number of "days in a year" being 2^74, and the number of "people" is the number you insert per millisecond. And what's more, unlike regular GUIDs, you can do these inserts for 700 years without the odds of a collision ever increasing, because the odds per millisecond are completely isolated from each other, because if you don't have a collision yet, the odds of the first guid for a millisecond colliding is 0. The odds of a second guid in a millisecond is 1 in 2^74

[@condar15]

Specifically looking at rough estimates you're looking at needing about 1e37 (ten trillion, trillion, trillion) generations in a single given millisecond to have a 50% chance of a conflict. Even if we assume there are enough UUIDs generated each millisecond to create some conflict, the chance that conflict occurs within the same system (which is what we really care about) is effectively non-existent.

[@vamvdotnet]

A question: isn`t this feature what Chris Pattersons`s (MassTransit`s creator) NewId nuget Package delivers for us already?

[@MayronDev]

That's a much needed improvement. I wish they could be shorter (such as the IDs used for youtube video IDs) but I'm not sure how easy that would be. Using IDs generated from timestamps feels safer, though.

[@uncommonbg]

There already are packages that do this. I’m using that in some of my new projects. Works really nicely combined with EF value generators.

[@user-wy2co5oq8i]

Usually, when I need to have primary key of GUID type, I'm doing the pair columns - GUID non clustered (primary key) + INT/BIGINT clustered autoincrement for avoiding full table sort after inserting new row.

[@NotACat20]

Inserting never requires "full table sort". Clustered index is all about sorting on leaf nodes (inside pages), while represented with tree on branches, exactly in same way as with regular index.

[@gunnarliljas8459]

It must be noted that this is REALLY BAD idea for SQL Server. MS SQL's uniqueidentifier is not sorted in the way UUIDv7 is. Don't use this with SQL Server.

[@screamiboy]

Yes valid and important point in this discussion! There are some v8 implementation, which are solving the issues in MSSQL, but we have to keep in mind, that v8 is a custom format without general specification.

[@lepingouindefeu]

Dude I've been waiting for this for so long!!!!!! I can't believe it's finally here. ❤❤❤❤

[@Marfig]

Well, the version 7 UUID cannot be used by services that expose these IDs to third-parties, through API calls for instance, or to frontends. The timestamp and counter portions of the UUIS have an implied security risk. You wouldn't want your customers to estimate how many invoices you generated last month, or when a certain part was added to your catalogue. It needs to be said that in relational databases, performant IDs that are also secure is still an unresolved problem. If you are in a scenario where security trumps performance, you definitely should go with version 4. Or better yet, go with another library like nanoid that can produce low collision IDs with a much smaller index size.

[@nickchapsas]

You can’t estimate how many of anything was generated last month with v7. You can just get when it was generated

[@Marfig]

@@nickchapsas That's correct. It's not version 7 that has a counter segment.

[@TGeorgie]

What customer cares when a company generated their invocie or when they added something to the catalogue? What can they even do with that info? I guess depending on the info it might be useful to competitors? Maybe? But if the creation date is not something you absolutely need to hide then there's no issue and quite a bit of benefit.

[@Marfig]

@@TGeorgie Security isn't evaluated like that. There are other scenarios were revealing the timestamp of a record generation can be a security risk. The reason why Version 7 UUID was never a popular choice for database primary keys is exactly because of the increased vulnerability to enumeration attacks, and the information a timestamp can reveal about the system it was generated on. Many companies in fact have the simple rule that no shared ID should reveal anything about the system or the data itself and should be completely random. If you work on the financial sector for instance, go on and try creating a version UUID on your database to serve as a PK. You'll get quite the PR comments.

[@deado7282]

"You wouldn't want your customers to estimate how many invoices you generated last month, or when a certain part was added to your catalogue." Even if you wouldn't want to, you have to. Sequential order-numbers are legally required in many cases. You can usually compose them, but it still has to contain a incremented number. You might be able to hide this number on your website for instance. But you have to disclose it customers who bought something anyway. Making the hiding part kinda pointless.

[@Grumpicles]

I love it when I can defer a problem with a statement like "I'm not going to worry about it, I'll be dead." 😂

[@danku1013]

EF Core supports sequential GUIDs for a long time.

[@SmoothNanners]

I believe it's only with SQL server with NEWSEQUENTIALID set as the database generated value and its implementation is different from UUID v7. Other DBs might need a plugin or don't support it.

[@scdecade]

If the guid is the unique clustered key in the database table then the performance is good. If the situation calls for it you can split apart the primary key and the clustered index

[@joeldickson5471]

Ordered fixes the problem of index fragmentation in databases. Which isn't a problem anymore because of ssd storage. I'm not sure if it's a problem with in memory storage (ie dictionary) would be keen to look at benchmarks

[@haxi52]

I have an `Id` type in my domain of all my projects. It implicitly converts from/to string/guid and a new static method that does similar to here, where the first few bytes are time ordered. I also like to encode two bytes of an enum that tell me which "table" the id belongs to.

[@leandroteles7857]

Sir, did you really just run a benchmark of GUID generation? Are you aware that you had just stolen 10000+ GUIDs from the universe? 🤣🤣🤣

[@ernstgreiner5927]

If one billion (1E9) people create one billion GUIDs per day on one billion planets, it would take more than 930 million Earth-years to exhaust all these GUIDs. Just how to grasp the vastness of GUID...

[@andreaskristensen3948]

Is it possible to retirieve the date time from the version 7 guid i.e. a method on the type?

[@jpfl17]

Nice video, Nick! Regards from Brazil.

[@utubekade]

Great feature. Thanks for sharing. Hope they find a more efficient way before they release this.

[@tofu1687]

We use EF or Database generated Guid which are sorted... but system dependant (ie. merging data from 2 databases on different machines might have an index issue)

[@MadafakinRio]

I'll stick to my auto-increment integers, thanks.

[@TheCodeCreator]

I guess I will too.

[@TheLucanicLord]

As will I. And my axe!

[@TheXenoEnder]

As long as you never need to partition your data for distribution that should be fine.

[@reikooters]

I'm using the RT.Comb package for this at the moment, but would be interesting to see how this compares

[@NickAskew]

I was trying to get my head around why it would be important that the GUID, UUID, or identifier is in order of creation. The old fashioned increment a counter system worked fine for smaller systems and automatically ensured this order. So if a table were clustered by the ID and that ID is an incrementing number then the new row can reliably be appended and no sorting is done, but why would you cluster by ID as that would lead always to clusters of size 1? OK so perhaps the issue is nothing to do with clustered indexes but just indexes. Each time a new row is added where the primary key is primary means of retrieval, the index b-tree will need to be adjusted in all cases. Is it faster to add data that is roughly in order to a b-tree? Well I guess it means that you are affecting a more predictable part of the tree rather than the GUID scatter gun approach.

[@alexdubinsky6098]

what about sequential guid? has been around for years

[@magnuspersson9740]

But if you create several directly after each other like in your example they are not sequential if I understood correctly? Since they get the same time stamp.

[@NickAskew]

I'm slightly confused here. I don't see how they are time ordered if the bytes after the time are not byte ordered unless the difference in the Unix time is less than 70 milliseconds. But I suppose even then occasionally two servers generating the new UUID could generate a UUID within that window of time.

[@leerothman2715]

Probably not a good idea on a noSql container/collection if it’s the partition key as you’ll end up with a hot partition?

[@atlesmelvr1997]

sequential guids have been available for a very long time

[@AslamNazeerShaikh]

Thanks for sharing wonderful knowledge with us ❤🎉

[@T___Brown]

I switched to mongodb style objectid. Its larger and better for url

[@weifengmao]

How does that compare to the newid package.

[@zsolter14]

So how does this solve that Guids are much larger than for example longs? Guids need twice as much storage than longs and sometimes it matters. What I am trying to say is that this new Guid will only replace the Guid IDs, but the long or int still has a use-case.

[@unexpectedkAs]

I expected a benchmark comparison between the nrw Guid and the existing libs.

[@venussmodzhd1886]

What about ULID?

[@Ulfius1984]

The samples created at 4:30 were not sequential

[@phizc]

That's not a guarantee with v7. The guarantee is to be grouped by milliseconds and highly unlikely to have a collision. Technically the last 78 bits doesn't have to be all random. They could contain a counter as well. I just skimmed Wikipedia's entry about it and I'm not sure why and how many bits has to be random. Tldr; Order is not guaranteed if you create multiple UIID v7 per millisecond.

[@pilotboba]

I'm not sure the string representation of a guid matches it's binary representation which is how it's stored and sorted. I could be wrong about this, and it would be nice to see a video about it.

[@Daniel15au]

​@@pilotbobathe string matches - it's just a hex representation of the bytes.

[@onelopez]

I had to create my own Guid that uses the time and also noticed that there's a performance hit whenever using this version. But it's worth the trade off imo for the speed gains in indexing

[@Daniel15au]

The difference shown in this video is around 40ns. That's tiny. Even if you were to create 1 million IDs, that's just an extra 40ms.

[@djupstaten2328]

It seems obvious that time should be in the code. Now mix in some serially unique info from the hardware creating the hash (like the ATPO of the CPU) and you have "place" also, making it impossible to duplicate. It could end up being hefty but probably not too bad.

[@JW-lv1fm]

Love this idea, wonder how many bits would be needed however. This might also reduce randomness/collision reduction capability. It might be better to just store the location in a separate field, or new dataType (GUIDL) that has an extra 8 bytes for location? This is only useful where GUIDs come from random sources anyways, so not needed for everyone's use case.

[@rupenanjaria]

How are you able to try this? pls share. Can we do it in SharpLab?

[@LilPozzer]

Hi Nick. How does someone migrate an existing huge microservices app from V4 to V7?

[@HappyCheeryChap]

Just change your generator for new rows from now on. Don't waste time changing existing data. The sooner you switch, the less you'll care about the older rows sooner too.

[@bryanstackpole1951]

Does it play nice with sequential guids?

[@SmoothNanners]

Will they also add a property to get the version of a Guid?

[@NickDarlow]

What build of .NET 9 is this in? It doesn't seem to be in preview 6?

[@nickchapsas]

Preview 7

[@farshadgoodarzi7077]

I think perhaps Snowflake ids are much more efficient, they are small in size (just a long number), sequential ordered by time just like UUID v7, no fragmentation in database (as UUID v4 has this kind of fragmentation because they are not necessarily sequential)

[@Corvin_]

I looked into this a while back and honestly I didn't see why this would be better than using an incremental int + guid column combo. 1 less column to index i guess. I'm not an expert though so if someone knows please enlighten me.

[@Max_Jacoby]

I always use autoincrement. I don't like the idea of possible collisions however small the chance is. Storing 128 bit instead of 32 is also a thing. It gives 12GB of data overhead if you have 1B records.

[@0xAC]

First of all it would be nice to see a benchmark of database performance rather than time which is spend generating UUIDs. Second of all if such generated UUID is visible outside, it drives to leakage of information. I would like to have a bit more honest comparison.

[@Grimlock1979]

4:24 Those are not ordered, though.

[@omriliad659]

was looking for that comment. it really needs an emphasis that while it aims to be sorted, it will not be sorted within the same second

[@JohanNordberg]

Don't think I've ever sorted something on PK. Don't really see how using a GUID as a PK with an unique index and a timestamp column with a sorted index would be a performance problem. Imo there is something wrong with the design if PK's are used to sort on creation order.

[@JollyGiant19]

It’s very common with int PKs in my experience. This lets one have the ergonomics of int PKs with the single round trip insertion performance of GUIDs. That’s all really.

[@pilotboba]

PK by definition is a sort.. and in SQL Server, it isn't only a sort, it is the order the rows are written to disk. So, if you aren't using a highly non-unique ever increasing value for it, you are getting a high amount of table fragmentation. Also, every lookup in a db eventually uses the PK. There are ways around it, mentioned in the video, turning off clustering on the guid pk and creating a clustered index on some other field. In SQL Server, if you a table without an index it is called a heap and not as performant to retrieve data from.

[@winstochurgle9133]

All I understood from the video is that the UUID takes longer to create than the standard GUID. Then what is the advantage of UUID?

[@ashbjorn]

How does this compare to a Sequential Guid?

[@JW-lv1fm]

A guid can be generated on any system anywhere, and mostly guarantee no duplicate key. A sequential requires knowing the last value, forcing you to lookup from the database as well.

[@Jallenbah]

@@JW-lv1fm No it doesn't. Sequential GUID is generally produces a portion of the data using a complete UTC timestamp accurate to the millisecond, so there is no need at all to know the last value.

[@JW-lv1fm]

@@Jallenbah Ahh, my bad. I didn't know "Sequential GUID" was a special name for an implementation. Thought he was using the general term. I suppose he did uppercase it to indicate.

[@zhaltys]

Can we parse timestamp back from this new guid easily?

[@markippo]

To be honest, from rdbs perspective, guids not being naturally sorted is the only one good thing that comes with them. And that's an asset only in highly concurrent environment when the last page contention problem occurs. But there are better (but more complicated) solutions for that. Never use guids, uuids, strings as a table primary keys (clustered). Nowadays apart from high index degradation, lower speed of dml operations (inserts), they're simply bad for a query performance. Each joining predicate costs you 256 bits instead of 64. Finały if someone run an analytical query - that will eat insane amount of ram and for sure introduce a table spooling. Guids are never good, use classic autoincremented ints instead, change them to bigints only if that's really necessary.

[@carlosbrockmann7604]

Do you think this new Version could be migrated to SQL-server?

[@CkW38]

7:08 You said 70 instead of 69. I'm disappointed in you Nick.

[@Daniel15au]

Why's they keep the long format for the new version? It could be way more compact if they used base62 encoding (using 0-9, a-z, A-Z, and a few symbols) rather than hex encoding (which is just 0-9 and a-f)

[@JulienMarpault]

Impossible to find this new method in preview 6. I found the code in the sources on Github. Did you used a nightly for this video ?

[@nickchapsas]

I'm on preview 7 but I thought they added it in preview 6

[@JulienMarpault]

@@nickchapsas Nope, your a bit early :) Preview 7 will be released in one month, we will have to be patient.

[@andriiyustyk9378]

That"s good but not perfect because the time resolution is 1ms. I think it would be better if random data had fewer bits, and time - more. If you have high loaded app and need to know for sure what the record was inserted first - only UUID v7 ID is not enough

[@roelbrook7559]

Didn't this already happen on SQL Server when you use auto-incrementing Guid types for the ID column? UUID7 is not really "new" - it is already a couple of years old. As per the RFC, you still need rand_a. So they seem to take the rand_a from a UUID4 - which I guess is a quick way to implement this.

[@leppyr64]

If you let SQL Server generate the guid with NEWSEQUENTIALID, yes. However if you have a number different clients generating their own guids and inserting, no.

[@SmoothNanners]

How much benefit does it provide over v4 in a PostgreSQL table for insertions, finds, etc if the primary column is of uuid type that uses b-tree index and you're not ever sorting that column? I read that column type is pretty optimized.

[@michaelkopljan578]

PK is always Cluster Key if is not told otherwise by table generation. You should read what is Cluster Key and how table pages are working, what is fill factor and etc.... GUID is worst PK you could think about it as it produce fragmation all the time in pages

[@diamondkingdiamond6289]

@@michaelkopljan578this is not true, the primary key in PostgreSQL is NOT a clustered index.

[@diamondkingdiamond6289]

@@michaelkopljan578this is not true, the primary key is NOT a clustered index in PostgreSQL

[@diamondkingdiamond6289]

@@michaelkopljan578this is not true. Primary keys are NOT clustered indexes in PostgreSQL. Also Nick, before you delete my comment again, do some research for gods sake. (If that is you)

[@HappyCheeryChap]

Regardless of speed... v4 also uses more storage space in indexes. Both on disk and in RAM. That was enough for me to switch to a sequential version alone. I'm actually using my own version where the date and HH:MM are human readable. Loving how practical and convenient that is.

[@OhhCrapGuy]

Well, this is better than making CreateDate my Clustered key and making my ID primary key non-clustered... Which is very much not the solution for a lot of problems, but it has worked on occasion...

[@KvapuJanjalia]

EF Core's sequential GUID generator does the same thing, no?

Guid is the same size as an IPv6 address and they don't seem to be losing sleep over it.

[@user-hb7py7xy7b]

Such a niche feature. GUIDs are fine in 99.9% of scenarios.

[@silkfire]

Is this Guid similar to the NewId package?

[@ekeke7125]

So basically using GUIDv4 means I don't care about time order, using GUIDv7 means I care about time order. I honestly would never go this way. If the data I have require a primary key and then later I need ability to sort by insertion time, that's basically a change of requirement, I'd rather implement Inserted as a separate datetime/timestamp column

[@isnotnull]

is this only for faster insert into?

In SQL Server fragmentation will come with a cost for read also. But as multiple has mentioned, in that case this would not help.

[@Stoney_Eagle]

Great... Just built my whole database and its logic using ULID's...

[@TomislavBukovac]

One of guid use cases was to mitigate solvable German tank problem. This is reintroducing it....

[@phizc]

If being able to estimate the number of records is more important than DB performance, v4 is probably better. Nice thing is that you can choose whether to continue using v4 or use v7 if performance is more important. Note: I didn't even know that the German tank problem meant before googling.. They would have to get many samples for IDs generated in a single millisecond to get any estimate of the total number of records, and there could be bursty behavior in the generation.

[@Grudzin7]

If you change half of the digits then you lose a lot of possible combinations, going from 2^128 ~3,4e+38 (time independent) to 2^64 ~1,8e+19 for each millisecond. So while inserting a milion records at once (assuming all have same unix timestamp) there is around 2.7e-8 chance of the any collision. It's small, but significantly bigger than original 1.4e-27 with "old" guid.

[@JW-lv1fm]

That's okay, if you have a collision - just wait 1 ms and try again. :) Those odds get reset every ms.

[@Grudzin7]

@@JW-lv1fm Not really... The case I'm referring to is when you insert a milion records in a single transaction (that's why all records have the same timestamp) and single collision will invalidate whole transaction and force rollback changes. This can be costly. Although it's not the case for most of the applications it may happen for example in some migration or integration apps and cause some trouble.

[@JW-lv1fm]

@@Grudzin7 Feed it an incrementing timestamp? Check for collision via hashset prior to insertion? Technically it gets the current timestamp every creation, so if you are batch processing, doing 1m records in the same ms seems unlikely. The use case means you can just stick with V4 too. Very few migrations/integrations should be inserting 1m in the same transaction, that's bad for many reasons.

[@Grudzin7]

​@@JW-lv1fm Then is 999 999 good? Or maybe 999 998? .... 800 000? ... 10 000? 100? 2? where is magic barrier after which there is too many records in single transaction? I've never heard of one. Quite opposite - I remember inserting few millions of records in single transaction by myself, not with same timestamp though. In many cases that is the only way you can keep the integrity of the data, even if something fails in the middle - that is whole point of having the transaction. It all depends what you are doing and what the primary goal is. I can think of several valid scenarios to have millions of records with the same timestamp, and for those scenarios this "new" guid significantly increases random probability of failure. And checking guids for collision? God, please, no. That's exactly why we have guids (globally unique!) in the first place.

[@levmatta]

I had a custom Guid implementation that did a similar thing. I can say that this is half the problem. Storing in the database is also terrible. We need 128bit int fields. Or Nick any other ideias? (That work across Oracle, SQL, Postgres)

[@JW-lv1fm]

124bit? Just store the first 124bits of this 128bit field. You know the first half is time, and the trailing bits are just random. I'm curious why 124bit though...

[@ghaf222]

You can also store as CHAR(36)?

[@levmatta]

@@ghaf222 it's what I am doing now. It is terrible!!! All indexes blow up in size and decrease performance

[@levmatta]

@@JW-lv1fm 128, my error

[@SheepyTaggerNep]

So it solves the Year 2038 problem by writing the unix time in 48 bits instead of 32?

[@lalithprasadsrigiriraju]

I am good with Integers

[@nicholaspreston9586]

See, this is why I love C# so much, and why, after being fired, I must continue using C# for all my contracts. There's just so much ingenuity and usefulness packed into C# since 1.0 and now this? Java/Javascript cannot compare. We have AOT now, XPlatform support, a multitude of great libraries that work out of the box like Dapper, Automapper, and Polly. Other languages wish they were C#!

[@desertfish74]

umm, C# is nice, but you might want to adjust the comparison a bit: much of that stuff is just a library and those usually have equivalent solutions in other languages. For these new ids for example, a simple package for Python is alreadly available since a couple of years. Granted, it's not in the standard library, but it's a single pip install uuid7 command away.

[@nicholaspreston9586]

@@desertfish74 "umm". What are you, 5yo?

[@Spirch]

this V7 isnt going to go well with sql server, fragmentation hell, sadly

[@rrahman-h6n]

What about Ulid?

[@MattThomson]

Here is a shoutout to all the developers in year 10000 using Chat GPT 472 with C#3 using .Net 1337 in the neural software link Microsoft Visual Universe Simulator Debugger (Education Edition) who run into this bug

[@amirchip]

What about NanoId and friends?

[@7eper]

But usually, don't we let the database create the ID?

[@JollyGiant19]

Some systems do, some don’t.

[@stevenj8261]

Using MassTransit NewId implementation already time ordered

[@_miranHorvat]

So guids get predictable?

[@greencol]

The current Guid has 122 bits of entropy (i.e 6 of the bits are known/guessable), and this has far less entropy than that, making it unsuitable for e.g. resource IDs in APIs in some circumstances.

[@JollyGiant19]

But that entropy resets every 1ms.

[@greencol]

@@JollyGiant19 The point is that a whole block of bits are now guessable that weren't before. An attacker attempting to guess an ID has a much smaller ID space to search. OWASP guidance for unguessable IDs is 128 random bits, the existing Guid already fell short of this by 6 bits.

[@kurtnelle]

So it's not globally unique but it should be system unique; which is unique enough. Also Developer: No need to worry about this, since in 8,000 years I will be dead Science: We found the cure for death! Developer: Shit..

[@solidid9368]

hmm I prefer that the DBMS generates the IDs for me... but nice to know

[@Crozz22]

Doesn't this increase chances of collisions dramatically? Enough to worry about it?

[@JollyGiant19]

Entropy resets every 1ms so it depends on your load. Most services won’t do enough inserting every millisecond for it to matter.

[@pilotboba]

@@JollyGiant19 It's "globallly" unique. So not just have to worry about guids in your system. (although that's generally the case). But, yea, I'm not worried about a collision with my own system at all.

[@chadgrant8870]

using guid's in a rdms is not that big of a deal, you still keep integer relationships for quick joins, you just don't expose them so they don't get enumerated in an attack

[@porcinetdu6944]

Can someone reexplain please, what is the winning it ? The fact that you can order ? I don’t understand why you could not and now you can

[@JollyGiant19]

GUID V4 is random so sorting gives a random output. GUID V7 has the first bits set to a timestamp so when ordered it’ll be the order of insertion (same as sequential PKs) instead of random.

[@porcinetdu6944]

@@JollyGiant19 thanks you it is clearer now

[@urzalukaskubicek9690]

Will this be added to EF core?

[@pilotboba]

EF core already generates a sequential id by default. You can also create a convention or convertor for Guid type that uses this if you want.

[@urzalukaskubicek9690]

@@pilotboba But it generates integers by default. Guid v7 by default would be nice.

[@pilotboba]

@@urzalukaskubicek9690 They might change the default SequentialGuidValueGenerator to guid v7. Perhaps create an issue for this. I will upvote it if you do.

[@pilotboba]

@@urzalukaskubicek9690 If the PK is a Guid it generates a "sequential" guid when you add the entity to the context.

[@dxhelios7902]

@nick you don't explain why? We already have sequential ID support in ef core. Trust me bro is not an explanation.