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https://issues.apache.org/jira/browse/PHOENIX-1954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14531716#comment-14531716
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Lars Hofhansl commented on PHOENIX-1954:
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Note that the more traditional {{ALTER SEQUENCE <seq> INCREMENT BY <N>}} does
not work, because it cannot atomically return the id it started from when there
are concurrent clients.
If/when we have transactions this can be achieved more naturally, albeit with
multiple roundtrips, and for Salesforce we'll need this soon'ish.
> Reserve chunks of numbers for a sequence
> ----------------------------------------
>
> Key: PHOENIX-1954
> URL: https://issues.apache.org/jira/browse/PHOENIX-1954
> Project: Phoenix
> Issue Type: Bug
> Reporter: Lars Hofhansl
>
> In order to be able to generate many ids in bulk (for example in map reduce
> jobs) we need a way to generate or reserve large sets of ids. We also need to
> mix ids reserved with incrementally generated ids from other clients.
> For this we need to atomically increment the sequence and return the value it
> had when the increment happened.
> If we're OK to throw the current cached set of values away we can do
> {{NEXT VALUE FOR <seq>(,<N>)}}, that needs to increment value and return the
> value it incremented from (i.e. it has to throw the current cache away, and
> return the next value it found at the server).
> Or we can invent a new syntax {{RESERVE VALUES FOR <seq>, <N>}} that does the
> same, but does not invalidate the cache.
> Note that in either case we won't retrieve the reserved set of values via
> {{NEXT VALUE FOR}} because we'd need to be idempotent in our case, all we
> need to guarantee is that after a call to {{RESERVE VALUES FOR <seq>, <N>}},
> which returns a value <M> is that the range [M, M+N) won't be used by any
> other user of the sequence. My might need reserve 1bn ids this way ahead of a
> map reduce run.
> Any better ideas?
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