7. A computer program product for eliminating redundant information in a log file having unknown grammar, the computer program product comprising: one or more computer-readable storage media and program instructions stored on the one or more computer-readable storage media, the program instructions comprising: program instructions to identify an alphanumeric string in a log file, the alphanumeric string comprising a plurality of alphanumeric substrings separated by non-alphanumeric characters, the plurality of alphanumeric substrings including at least two distinct alphanumeric substrings; program instructions to replace each alphanumeric substring of the plurality of alphanumeric substrings with a first alphanumeric character to generate a first resulting string that includes the non-alphanumeric characters and multiple occurrences of the first alphanumeric character; program instructions to replace each pair of characters of the first resulting string that is identical to another pair of characters of the first resulting string with a second alphanumeric character to generate a second resulting string, wherein the program instructions to replace each pair of characters of the first resulting string that is identical to another pair of characters of the first resulting string with a second alphanumeric character to generate a second resulting string comprise: program instructions to, responsive to determining that there are multiple distinct pairs of characters of the first resulting string that are identical to another pair of characters of the first resulting string and that the multiple distinct pairs of characters occur an equal number of times in the first resulting string, select a pair of the multiple distinct pairs of characters based on a pre-defined hierarchy of characters included in the multiple distinct pairs of characters, and program instructions to replace the selected pair of characters with a second alphanumeric character to generate a second resulting string; and program instructions to replace consecutive occurrences of the second alphanumeric character, in the second resulting string, with one occurrence of the second alphanumeric character to generate a compressed string.
12. The computer program product of claim 7 , further comprising: program instructions to identify an additional second compressed string having a similar structure as the generated compressed string; and program instructions to highlight the generated compressed string and the additional compressed string in a user interface.