Question

I’m looking for a way to improve this regular expression:

^(?:([^.]+).?){6}_tid

This extracts the 6th field of a point.separated.string.of.arbitrary.lengths up to “_tid”

So if it looks like this:

mc11_7tev.138345.dgnol_tb6_m12u_140_140_110_2l_jimmy_susy.evgen.log.e825_tid431423_0

it should return

e825

Funnily enough, if I remove the _tid part of the regex ^(?:([^.]+).?){6}, I get the performance I was looking for.. 1 to 2 seconds for a million strings to check.
With the _tid.. it takes up to 5 minutes.

Is there a better way to do this?

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EDIT:
Ah, I forgot to mention, this is in Apache Pig, so everything should be in the regex clause.

Answer 1

You forgot to escape the dot, try this

^(?:([^.]+)\.?){6}_tid

this way your regex has much less possibilities to match. The “.” without escaping matches any character (without line break characters).

The other possibility I see is getting rid of the optional dot

^(?:[^.]+\.){5}([^.]+)_tid

See it here on Regexr