In the manual, it is stated that a write is sent to multiple loggers,
written to the wa log and key/value pairs stored in a memtable and an
index.

Since the write hits several servers for resiliency, does each of the
servers that receives the write place the same data in memory or do
they each place a different portion in memory such that a read could
span multiple servers for a performance gain?

Thanks,

-Kris

I believe only the tablet server which currently hosts the tablet which
contains the key which you inserted will contain that pair in the
in-memory map (memtable).

The pair hitting multiple loggers ensures that the data is not lost, but
since a tablet is only ever hosted by one server at a time, the k/v pair
is not placed into multiple servers' memory map.

On 11/1/12 7:34 AM, Kristopher Kane wrote:
> In the manual, it is stated that a write is sent to multiple loggers,
> written to the wa log and key/value pairs stored in a memtable and an
> index.
>
> Since the write hits several servers for resiliency, does each of the
> servers that receives the write place the same data in memory or do
> they each place a different portion in memory such that a read could
> span multiple servers for a performance gain?
>
> Thanks,
>
> -Kris

On Thu, Nov 1, 2012 at 4:34 AM, Kristopher Kane <[EMAIL PROTECTED]>wrote:

> In the manual, it is stated that a write is sent to multiple loggers,
> written to the wa log and key/value pairs stored in a memtable and an
> index.
>
> Since the write hits several servers for resiliency, does each of the
> servers that receives the write place the same data in memory or do
> they each place a different portion in memory such that a read could
> span multiple servers for a performance gain?
>

Reads only use a single server, so only the tablet server hosting the
tablet puts the data in memory.  On other machines it is just logged to
disk.

Billie

>
> Thanks,
>
> -Kris
>

> Reads only use a single server, so only the tablet server hosting the tablet
> puts the data in memory.  On other machines it is just logged to disk.
Great.  Thanks.

-Kris