Hi,
TL;DR: I have inconsistend data (1 live row on node A & 1 tombstoned row
on node B) that do not get fixed by repair. What can be a problem?
Long version:
I have a CF containing Users' info, which I sometimes query by key, and
sometimes by indexed columns like email. I'm using RF=2. I write with
CL.ONE, but this CF is very rarely updated, so C* has a looot of time
to fix inconsistencies that may occur, so I'm fine with this (at least
in theory ;-) ).
To be clear:
- I've run a successfull cluster-wide repair on this CF before testing,
so I do not expect any inconsistency
- All indexes are built, I've rebuilt them manually before testing, so I
expect them to work properly (I mention it because it seems to be
somehow related to indexes, but I'm not sure - see below)
The problem is:
When I query (cqlsh) some rows by key (CL is default = ONE) I _always_
get a correct result. However, when I query it by indexed column, it
returns nothing.
When tracing a query with CL.ALL in cqlsh, I get info that C* has:
Read 0 live cells and 1 tombstoned // for first replica node
Read 1 live cells and 0 tombstoned // for second replica node
When CL is ONE it's never asking second replica for data (possibly due
to DynamicSnitch scores or so), so it returns nothing.
Switching to CL >= TWO obviously fixes this problem for us, but it's not
the solution I'd like to use as I'd rather rely on fast read/write
requests with CL.ONE + frequent repairs, allowing some short-term
inconsistency.
Any ideas why it may happen that data are still inconsistent after
repair? Is there something I could have missed?
I'm mainly surprised that repair does not fix this inconsistency in ANY
way - either by pulling missing data to first replica _OR_ tombstoning
it on second replica. First one would be correct (delete was made a long
time ago and then the row reappeared), but both could make sense, as
both will make the data consistent. In this state it's definitely
inconsistent and I don't understand it :-)
M.
