Lars Hofhansl created PHOENIX-1954:
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Summary: 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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