[VOTE] Release Apache Cassandra 2.1.0-rc2
We've almost there. I propose the following artifacts for release as 2.1.0-rc2. sha1: e2bef02e254a9c6e37a86cab957a1fcba56214fd Git: http://git-wip-us.apache.org/repos/asf?p=cassandra.git;a=shortlog;h=refs/tags/2.1.0-rc2-tentative Artifacts: https://repository.apache.org/content/repositories/orgapachecassandra-1014/org/apache/cassandra/apache-cassandra/2.1.0-rc2/ Staging repository: https://repository.apache.org/content/repositories/orgapachecassandra-1014/ The artifacts as well as the debian package are also available here: http://people.apache.org/~slebresne/ The vote will be open for 72 hours (longer if needed). [1]: http://goo.gl/VeKNTk (CHANGES.txt) [2]: http://goo.gl/HHFAJU (NEWS.txt)
static columns and TTL - wouldn't it be nice if static columns played nice with a partition whose partition keys have all (TTL) expired
So, I was thinking about a new use case, where an ideal situation would be to
have something like
CREATE TABLE series {
id uuid,
inserted timeuuid,
small_thing blob,
large_static_thing blob static,
PRIMARY KEY (id, inserted)
}
So this is my first use of static columns, but I also want to use TTL (I just
built 2.0.8 to play with)
https://issues.apache.org/jira/browse/CASSANDRA-6782 and friends are pretty
confusing when it comes to TTL and the row marker, but from my playing, it
seems at least you can control behavior because you can (re) INSERT the primary
key values only using or not using a TTL. (Side node docs still say UPDATE and
INSERT are identical which is strictly no longer true)
So what I really want is the ability to do
INSERT INTO series (id, large_static_thing)
then repeated
INSERT INTO series (id, inserted, small_thing) VALUE (a, b, c) USING TTL X;
and have the partition (and the static column) disappear when the last “row”
for the partition key is gone.
I can get this behavior if I update the large_static_thing every time along
with inserting small_thiing, but that is exactly what I don’t want to do
because it is large and static.
It sort of seems semantically right that a special column that is shared by
all the rows of the same partition” should at least have an option to have it
expire when all “rows” expire.
It seems like this would be technically feasible (though very much non trivial)
if you had a syntax, say “large_static_thing blob static autoexpiring”, to make
the static column an ExpiringColumn, and have any row updates with TTL insert a
new OnDiskAtom type (that contains a TTL but no value) for the static column.
These could be reconciled/reduced/compacted or whatever with the ExpiringColumn
during read and compaction.
It all sounds a bit over-complicated… so:
1) Does this sounds like a useful feature, or is it a me only use case
2) Can someone think of a way to model this reasonably efficiently today
without using TTL on the static column (and thus having to rewrite it every
time) - not that I’m trying to be abusive and I haven’t thought this thru, but
my spider sense makes me think that maybe I can abuse an index on a small
expiring column to quickly find empty partition keys
3) Is it actually simpler to implement than I think in the code base (This is
the first time I’ve peeked at these areas of the code)
4) If implemented as I suggested above, does that have to be done in a major
version?
Thanks,
Graham
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Re: static columns and TTL - wouldn't it be nice if static columns played nice with a partition whose partition keys have all (TTL) expired
Note, that as I think about it, if you had the new OnDiskAtom time with TTL and
no value, then you wouldn’t need anything special about static columns, you’d
just need a CQL syntax to update/set the TTL for a column which might be useful
for lots of things.
On Jun 24, 2014, at 12:22 AM, graham sanderson gra...@vast.com wrote:
So, I was thinking about a new use case, where an ideal situation would be to
have something like
CREATE TABLE series {
id uuid,
inserted timeuuid,
small_thing blob,
large_static_thing blob static,
PRIMARY KEY (id, inserted)
}
So this is my first use of static columns, but I also want to use TTL (I just
built 2.0.8 to play with)
https://issues.apache.org/jira/browse/CASSANDRA-6782 and friends are pretty
confusing when it comes to TTL and the row marker, but from my playing, it
seems at least you can control behavior because you can (re) INSERT the
primary key values only using or not using a TTL. (Side node docs still say
UPDATE and INSERT are identical which is strictly no longer true)
So what I really want is the ability to do
INSERT INTO series (id, large_static_thing)
then repeated
INSERT INTO series (id, inserted, small_thing) VALUE (a, b, c) USING TTL X;
and have the partition (and the static column) disappear when the last “row”
for the partition key is gone.
I can get this behavior if I update the large_static_thing every time along
with inserting small_thiing, but that is exactly what I don’t want to do
because it is large and static.
It sort of seems semantically right that a special column that is shared by
all the rows of the same partition” should at least have an option to have
it expire when all “rows” expire.
It seems like this would be technically feasible (though very much non
trivial) if you had a syntax, say “large_static_thing blob static
autoexpiring”, to make the static column an ExpiringColumn, and have any row
updates with TTL insert a new OnDiskAtom type (that contains a TTL but no
value) for the static column. These could be reconciled/reduced/compacted or
whatever with the ExpiringColumn during read and compaction.
It all sounds a bit over-complicated… so:
1) Does this sounds like a useful feature, or is it a me only use case
2) Can someone think of a way to model this reasonably efficiently today
without using TTL on the static column (and thus having to rewrite it every
time) - not that I’m trying to be abusive and I haven’t thought this thru,
but my spider sense makes me think that maybe I can abuse an index on a small
expiring column to quickly find empty partition keys
3) Is it actually simpler to implement than I think in the code base (This is
the first time I’ve peeked at these areas of the code)
4) If implemented as I suggested above, does that have to be done in a major
version?
Thanks,
Graham
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