Hi deepthi,
There are multiple ways you can handle this. A few here...
If you have the option to reorganize the input, You can use a separate "unique" sourcetype and you can just search by sourcetype="XXXX" or if it makes sense in your env... even get this data in a separate index as being suggested by piUek
Or
You can maintain "tags" and just use the tag instead of source. Eg: Create a tag "myrtrs" and maintain all your sources there.
Tag Name: myrtrs -- source=abc1,source=abc2... etc
or
You can name your sources logically. Eg: If you prefeix your csv files with something unique like myrtrs_yourcurrentname you can just use a wild card
source=myrtrs_* ....
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