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https://issues.apache.org/jira/browse/PHOENIX-1954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14538917#comment-14538917
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James Taylor commented on PHOENIX-1954:
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bq. Would you consider it an error if a statement specifies NEXT 1000 VALUES
FOR seq and executes it 1001 times? Is the caller committing to allocate no
more than 1000 values?
The client would be responsible for preventing/recognizing that case - Phoenix
would just reserve the asked for number of sequence values. It's possible that
if the client didn't ask for enough, then they could execute a new {{NEXT <n>
VALUE FOR <seq>}} with a bigger value for <n>.
> 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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