Add function generateSnowflakeID

[kazalika]

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• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Added new SQL functions generateSnowflakeID for generating Twitter-style Snowflake IDs.

Documentation entry for user-facing changes

• Documentation is written (mandatory for new features)

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[den-crane]

merged:

• Add UUIDv7-generating functions #62852

[den-crane]

#56228 (comment)

[robot-ch-test-poll2]

This is an automated comment for commit 1425f07 with description of existing statuses. It's updated for the latest CI running

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[rschu1ze]

@kazalika I reverted generateSerialID in reference to my comment.

Please create a new PR for generateSerialID, using a revert of the reverting commit as a starting point, thanks!

[alexey-milovidov]

@rschu1ze, are you sure we need two functions?

Why not have a single function that acquires global monotonic increments per each block and processes a block without synchronization?

It does not matter if it does not strictly follow the spec of Snowflake ID.

But having these two functions is unnecessarily obscure and complicated for an end-user.

[rschu1ze]

@alexey-milovidov The original motivation for two functions was generateUUIDv7 which comes in three forms (the "non-monotonic" variant does not make sense for snowflake ids so it was omitted).

Anyways, thinking about it, the use case for generateSnowflakeIDThreadMonotonic is indeed quite obscure. Let me remove it (--> #64499). If there is an actual need / use case, we can restore the code.

Besides that, the "normal" generateSnowflakeId works just the way you described. It acquires a global monotonic increment per block and, if this succeeds, it needs no further synchronization.

[alexey-milovidov]

@rschu1ze Thank you!
Let's also re-think UUIDv7. Maybe we can get away with a single function, and it will be better UX?

[rschu1ze]

@alexey-milovidov Looking at the original PR, I guess the only reason to introduce NonMonotonic and ThreadMonotonic variants for generateUUIDv7 was that performance of the standard function was not great because of locking. Besides that, I agree that these two variants lack a good use case.

Revert: #64506
I also opened #64507 for newcomers to improve the locking in generateUUIDv7.

[franz101]

@kazalika really awesome implementation, I wonder though if the API is a bit inconsistent:
#64713

snowflakeToDateTime(generateSnowflakeID()::Int64) will return 2065-04-04 23:58:22
on the other hand there is no way to pass an epoch to generateSnowflakeID(1, 1288834974)
while the snowflakeToDateTime always assumes epoch 1288834974

[den-crane]

@kazalika

• SnowflakeID type inconsistency (Int64 vs UInt64) #64733