Forum Discussion
Negative Lookahead with Regular expression in Kusto Log Analytics
Hello everyone, I'm trying to extract exceptions within our logs using regular expression. And it happens that I need to perform a negative lookahead to ignore a specific string. The query looks ...
Noa Kuperberg
Microsoft
MicrosoftApparently the full explanation is here. Quoting from it:
"Kusto uses the re2 library: https://github.com/google/re2/wiki/Syntax, as mentioned here: https://docs.microsoft.com/en-us/azure/kusto/query/re2
What you're trying to achieve isn't supported by that library - see https://github.com/google/re2/wiki/WhyRE2:
'As a matter of principle, RE2 does not support constructs for which only backtracking solutions are known to exist. Thus, backreferences and look-around assertions are not supported.'"
Noa Kuperberg thanks for the information on the RE2 library. Negative lookahead would be very useful in some cases. 😕 would be great if this could be added somehow. Why not use System.Text.RegularExpressions instead of re2? 😛
