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From Jonathan Ellis <>
Subject Re: scans stopped returning values for some keys
Date Thu, 10 Jun 2010 21:26:22 GMT
How is your CF defined?  (what comparator?)

did you try start=empty byte array instead of Long.MAX_VALUE?

On Wed, Jun 9, 2010 at 8:06 AM, Pawel Dabrowski <> wrote:
> Hi,
> I'm using Cassandra to store some aggregated data in a structure like this:
> KEY - product_id
> SUPER COLUMN NAME - timestamp
> and in the super column, I have a few columns with actual data.
> I am using a scan operation to find the latest super column (start=Long.MAX_VALUE, reversed=true,
count=1) for a key, which worked fine for quite some time.
> But recently I needed to remove some of the columns within the super columns.
> After that things got weird: for some keys, the scan for latest super column work normally,
but for some of them they stopped returning any results. I checked the data using the CLI
and the data is obviously there. I can get it if I specify the super column name, but scanning
for latest does not work. If I scan for previous data (start=some other timestamp less than
maximum timestamp in cassandra), it works fine.
> I compared the data for keys that work, and those that don't, but there is no difference
- the super column names are exactly the same and they contain the same amounts of columns.
> But the really weird thing is that the scans did not stop working immediately after some
columns were removed. I was able to scan for the data and verify that the columns were removed
correctly and only after a couple of minutes some scans stopped returning data. When I looked
in the log, I've seen that Cassandra has been doing some compacting, flushing and deleting
of .db files more or less at the time that the scans stopped working.
> I tried restarting Cassandra, but it did not help.
> Anyone had a similar problem?
> regards
> Pawel Dabrowski

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support

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