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https://issues.apache.org/jira/browse/PHOENIX-1422?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14242194#comment-14242194
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Lars Hofhansl commented on PHOENIX-1422:
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:)
START WITH and INCREMENT BY would not be supported. GENERATE_ID() is nice. On
another channel I proposed something like CREATE STATELESS SEQUENCE.
As for collisions... It depends how we do it. In theory we could just generate
a 64 bit number (or 63 bit maybe). The chances of there being duplicate are
lower than a meteor destroying your data center (assuming a good random number
generator). Similarly to what is proposed above, it's possible to generate
HLC looks like it needs some global state (c as described in the link)?
> Stateless Sequences
> -------------------
>
> Key: PHOENIX-1422
> URL: https://issues.apache.org/jira/browse/PHOENIX-1422
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Lars Hofhansl
>
> [~apurtell] and I were chatting yesterday.
> It would be good if Phoenix had stateless sequences, i.e. sequences that give
> out unique ids with (very) high probability.
> We can do that by starting with a timestamp, shifting it left 16 or 24 bits
> left and fill in the new bits with a random number.
> So we're guaranteed to get a new id for each millisecond and within a
> millisecond we break the tie with a random number. If we can make the
> likelihood of duplicate numbers lower than (say) a data center failure, we're
> OK. I would test this with a upsert into x ... select from x ... type query
> inserting 100's of millions of rows.
> Need to think of a syntax too.
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