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                              WORKLOG TASK
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TASK...........: Implement a new modifier for flush table
CREATION DATE..: Thu, 22 Oct 2009, 12:25
SUPERVISOR.....: Bothorsen
IMPLEMENTOR....: 
COPIES TO......: Bothorsen
CATEGORY.......: Server-RawIdeaBin
TASK ID........: 57 (http://askmonty.org/worklog/?tid=57)
VERSION........: WorkLog-3.4
STATUS.........: Un-Assigned
PRIORITY.......: 60
WORKED HOURS...: 0
ESTIMATE.......: 0 (hours remain)
ORIG. ESTIMATE.: 0

PROGRESS NOTES:



DESCRIPTION:

Create a patch to implement a modifier for  
"flush table" that allows you to only flush a limited number of  
blocks.

One of the difficulties we have is that we would like to  
persist some things to disk, but flushing an entire table worth of  
delay_key_write'd indexes takes minutes, during which time the server  
is so I/O bound that it cannot serve read traffic.  If it was possible  
to spread this flush over time, we would be able to actually do it  
without removing the server from read production beforehand.

Monty answered this question in an email:

The right way to do this is probably to add a background thread that flushes
blocks in a 'slow' manner.

Note that in the Maria storage engine we do already have this, but I
wouldn't recommend you to use this yet;  This is more a note about
what to expect in the future..


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