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From Bhuvan Rawal <>
Subject Re: why dose it still have to seach in SSTable when getting data in memtable in the read flow?
Date Mon, 27 Mar 2017 12:12:44 GMT
Also Cassandra working unit is Cells so in a partition there may be
possibility of some cells in a row being present in memtable and others may
be located in memtable therefore the need of reconciling partition data.

@Jason's point is valid too - User defined timestamp  may put sstable cells
ahead of memtable ones.


On Mon, Mar 27, 2017 at 5:29 PM, jason zhao yang <> wrote:

> Hi,
> Cassandra uses last-writetime-win strategy.
> In memory data doesn't mean it is the latest data due to custom write
> time, if data is also in Sstable, Cassandra has to read it and reconcile.
> Jasonstack
> On Mon, 27 Mar 2017 at 7:53 PM, 赵豫峰 <> wrote:
>> hello, I get the message that "If the memtable has the desired partition
>> data, then the data is read and then merged with the data from the
>> SSTables. The SSTable data is accessed as shown in the following steps."
>> in "how is data read?" chapter  in
>> archived/cassandra/2.2/cassandra/dml/dmlAboutReads.html.
>> I do not understand that why have to read SSTable when it has got target
>> data in memtable. If the data is in memtable, it means that data is lastest
>> one, is there any other reason that it still has to seach in SSTable?
>> Thanks!
>> ------------------
>> 赵豫峰
>> 环信即时通讯云/研发

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