sequential-uuids
spec
sequential-uuids | spec | |
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7 | 62 | |
293 | 8,648 | |
- | 1.4% | |
3.6 | 0.0 | |
7 months ago | 4 months ago | |
C | ||
MIT License | GNU General Public License v3.0 only |
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sequential-uuids
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Choosing a Postgres Primary Key
Disclaimer: not a dba so my terms might not be appropriate
I’ve seen uuid4 which replaces the first 4 bytes with a timestamp. It was mentioned to me that this strategy allows postgres to write at the end of the index instead of arbitrarily on disk. I also presume it means it has some decent sorting.
[inspiration](https://github.com/tvondra/sequential-uuids/blob/master/sequ...)
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Install extensions from PGDG repo to YugabyteDB - example with sequential_uuids
yum install -y git git clone https://github.com/tvondra/sequential-uuids.git ysqlsh -h $(hostname) --echo-all --quiet \ --file sequential-uuids/test/sql/uuids.sql | sdiff sequential-uuids/test/expected/uuids.out -
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Using a custom GUID (not provided by Postgres). What to keep in mind for performance gains
If you want to keep locality when using uuids, use a different generation function such as: https://github.com/tvondra/sequential-uuids
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Any significant performance disadvantage to using uuid as primary key?
OP, have a pretty large B2B SAAS app with all UUID pkeys, and the largest issues i'd say with UUID compared to bigint are: size, index bloat, WAL bloat, much slower GIST indexes (for exclusion constraints). You can work around some of the issues (WAL bloat, index bloat) by using a better behaved UUID generation function: https://github.com/tvondra/sequential-uuids You can get something similar for your app side of things if you need to generate UUIDs there.
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Timeflake: 128-bit, roughly-ordered, URL-safe UUIDs
Use this: https://github.com/tvondra/sequential-uuids
If you cannot install extensions, I just wrote a PL/PGSQL implementation for the time-based generator I could share.
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UUID vs int for primary key - Which is better (with auto increment), especially if you are scared you'll run out of ids?
Just fyi, UUID in Postgres is not 40 text chars, it's 16 bytes binary and has a canonical text representation. Also, you don't need to use UUIDv4, I am quite partial to: https://github.com/tvondra/sequential-uuids
spec
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The UX of UUIDs
Can use ULID to "fix" some issues
https://github.com/ulid/spec
- Ulid: Universally Unique Lexicographically Sortable Identifier
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Ask HN: Is it acceptable to use a date as a primary key for a table in Postgres?
Both ULID and UUID v7 have a time code component which can be extracted.
It would be best for indexing to store the actual value in binary, though not strictly necessary as these later UUID standards (unlike conventional UUIDs) use time code prefixes (so indexing clusters.)
https://uuid7.com/
https://github.com/ulid/spec
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Bye Sequence, Hello UUIDv7
UUIDv7 is a nice idea, and should probably be what people use by default instead of UUIDv4.
For the curious:
* UUIDv4 are 128 bits long, 122 bits of which are random, with 6 bits used for the version. Traditionally displayed as 32 hex characters with 4 dashes, so 36 alphanumeric characters, and compatible with anything that expects a UUID.
* UUIDv7 are 128 bits long, 48 bits encode a unix timestamp with millisecond precision, 6 bits are for the version, and 74 bits are random. You're expected to display them the same as other UUIDs, and should be compatible with basically anything that expects a UUID. (Would be a very odd system that parses a UUID and throws an error because it doesn't recognise v7, but I guess it could happen, in theory?)
* ULIDs (https://github.com/ulid/spec) are 128 bits long, 48 bits encode a unix timestamp with millisecond precision, 80 bits are random. You're expected to display them in Crockford's base32, so 26 alphanumeric characters. Compatible with almost everything that expects a UUID (since they're the right length). Spec has some dumb quirks if followed literally but thankfully they mostly don't hurt things.
* KSUIDs (https://github.com/segmentio/ksuid) are 160 bits long, 32 bits encode a timestamp with second precision and a custom epoch of May 13th, 2014, and 128 bits are random. You're expected to display them in base62, so 27 alphanumeric characters. Since they're a different length, they're not compatible with UUIDs.
I quite like KSUIDs; I think base62 is a smart choice. And while the timestamp portion is a trickier question, KSUIDs use 32 bits which, with second precision (more than good enough), means they won't overflow for well over a century. Whereas UUIDv7s use 48 bits, so even with millisecond precision (not needed) they won't overflow for something like 8000 years. We can argue whether 100 years us future proof enough (I'd argue it probably is), but 8000 years is just silly. Nobody will ever generate a compliant UUIDv7 with any of the first several bits aren't 0. The only downside to KSUIDs is the length isn't UUID compatible (and arguably, that they don't devote 6 bits to a compliant UUID version).
Still feels like there's room for improvement, but for now I think I'd always pick UUIDv7 over UUIDv4 unless there's an very specific reason not to.
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50 years later, is Two-Phase Locking the best we can do?
I'd love for Postgres to adopt ULID as a first class variant of the same basic 128bit wide binary optimized column type they use for UUIDs, but I don't expect they will, while its "popular" its not likely popular enough to have support for them to maintain it in the long run... Also the smart money ahead of time would have been for the ULID spec to sacrifice a few data bits to leave the version specifying sections of the bit field layout unused in the ULID binary spec (https://github.com/ulid/spec#binary-layout-and-byte-order) for the sake of future compatibility with "proper" UUIDs... Performing one big bulk bitfield modification to a PostgreSQL column would have been much less painful than re-computing appropriate UUIDv7 (or UUIDv8s for some reason) and then having to perform a primary key update on every row in the table.
- FLaNK Stack Weekly for 12 September 2023
- You Don't Need UUID
- UUID Collision
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Type-safe, K-sortable, globally unique identifier inspired by Stripe IDs
Many people had the same idea. For example ULID https://github.com/ulid/spec is more compact and stores the time so it is lexically ordered.
- ULID: Universally Unique Lexicographically Sortable Identifier
What are some alternatives?
Pomelo.EntityFrameworkCore.MySql - Entity Framework Core provider for MySQL and MariaDB built on top of MySqlConnector
dynamodb-onetable - DynamoDB access and management for one table designs with NodeJS
timeflake - Timeflake is a 128-bit, roughly-ordered, URL-safe UUID.
uuid6-ietf-draft - Next Generation UUID Formats
pg_tuid - generate_tuid function for postgres
kuuid - K-sortable UUID - roughly time-sortable unique id generator
id128 - 128-bit id generation in multiple formats
python-ksuid - A pure-Python KSUID implementation
uulid.go - ULID-UUID compatibility library for generating and parsing ULIDs.
ulid-lite - Generate unique, yet sortable identifiers
umbrella - ⛱ Broadly scoped ecosystem & mono-repository of 192 TypeScript projects (and 157 examples) for general purpose, functional, data driven development
shortuuid.rb - Convert UUIDs & numbers into space efficient and URL-safe Base62 strings, or any other alphabet.