Hi, 

I am currently working on JIRA issue: [1]. 


When deleting data from multiple timeseries, a successful deletion will leave a 
record in mods file for each timeseries.  
Suppose we executing "delete from root.sg1.d1.*" or "delete timeseries 
root.sg1.d1.* " when d1 contains N measurements.
We would write at most N lines of records in each mods file, however, this may 
cause performance issue if N is very large.


My optimization plan is:
In Mods files, we record exact the same path string that user specified. For 
example, "delete from root.sg1.d1.sd1.*" will write "root.sg1.d1.sd1.*" into 
mods file as path. 
In this way, for each timeseries path in delete statement, we access each Mods 
file once at most.
As a tradeoff, a path string matching is needed during query, to check if the 
timeseries has any modifications in mods files.


Any suggestions are welcome.


Thanks,


[1] https://issues.apache.org/jira/projects/IOTDB/issues/IOTDB-829?


---------------------
Wei Shao

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