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From z11373 <z11...@outlook.com>
Subject question on AgeOffFilter
Date Wed, 10 Jun 2015 17:53:37 GMT
Hi,
I have questions on using AgeOffFilter. Earlier I ran following:

root@dev> createtable testiter
root@dev testiter> insert 1 cf col1 foo
root@dev testiter> scan
1 cf:col1 []    foo

Then two hours later, I ran:

root@dev testiter> setiter -ageoff -t testiter -p 15 -minc
AgeOffFilter removes entries with timestamps more than <ttl> milliseconds
old
----------> set AgeOffFilter parameter negate, default false keeps k/v that
pass accept method, true rejects k/v that pass accept method:
----------> set AgeOffFilter parameter ttl, time to live (milliseconds):
30000
----------> set AgeOffFilter parameter currentTime, if set, use the given
value as the absolute time in milliseconds as the current time of day:

root@dev testiter> scan
1 cf:col1 []    foo

root@dev testiter> flush -w
2015-06-10 17:10:12,124 [shell.Shell] INFO : Flush of table testiter
completed.

root@dev testiter> scan
1 cf:col1 []    foo

*First question*, why that key/value still exists? I'd think since I set the
TTL to 30 seconds, and that key/value has been created more than 2 hours
ago, so it should be gone after table flush (minc)?

Then later I did following:

root@dev testiter> insert 2 cf col1 bar
root@dev testiter> scan
1 cf:col1 []    foo
2 cf:col1 []    bar

Wait for more than 30 seconds, then ran:

root@dev testiter> flush -w
2015-06-10 17:16:38,903 [shell.Shell] INFO : Flush of table testiter
completed.
root@dev testiter> scan
1 cf:col1 []    foo

This is correct as the second key/value pair no longer exist, but why the
first one still there?

*Second question*, I still don't fully understand the currentTime argument.
Since I didn't specify any long value (when being prompted), I'd assume it
took current time when I set the iterator, is it true? I am not sure because
if that is the case then key/value items inserted later won't get aged off
since they will have later timestamp than that value set by iterator. This
is also not true as shown in my example above (which second item was gone).
I hope someone can enlighten me on this.

*Third question*, which is kind of related to 2nd question. If I want to
have data in a table retained for 6 months, i.e. if compaction runs
everyday, then all key/value items with timestamp six months older than that
day will be gone, how can I achieve this? I guess that AgeOffFilter is the
right way to do, but the results from #1 and #2 above are confusing me, and
think it doesn't work as I wanted to.


Thanks,
Z



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