8. A system, comprising: a storage device operable for storing event data in a log file; and one or more data processing devices configured to perform operations comprising: transforming the event data into attribute/value pairs; generating an index mapping at least one of the attribute/value pairs to a reference pointer that references an instance of event data in the log file, the instance of event data in the log file including a textual message from which the attribute/value pair was transformed; generating an attribute co-occurrence data structure, the attribute co-occurrence data structure identifying a relationship between a first attribute in the attribute/value pairs and a second attribute in the attribute/value pairs, where existence of the relationship between the first attribute and the second attribute indicates that reports for finding a textual message including both the first attribute and the second attribute are allowable; and in response to a query including the first attribute, generating a report based on the attribute co-occurrence data structure and the attribute/value pairs in the index, including: identifying the second attribute based on the relationship identified in the attribute co-occurrence data structure; identifying an attribute/value pair that includes the second attribute; and generating the report, including providing access to the event data in the log file using a reference pointer that is mapped to the identified attribute/value pair in the index.
8. A system, comprising: a storage device operable for storing event data in a log file; and one or more data processing devices configured to perform operations comprising: transforming the event data into attribute/value pairs; generating an index mapping at least one of the attribute/value pairs to a reference pointer that references an instance of event data in the log file, the instance of event data in the log file including a textual message from which the attribute/value pair was transformed; generating an attribute co-occurrence data structure, the attribute co-occurrence data structure identifying a relationship between a first attribute in the attribute/value pairs and a second attribute in the attribute/value pairs, where existence of the relationship between the first attribute and the second attribute indicates that reports for finding a textual message including both the first attribute and the second attribute are allowable; and in response to a query including the first attribute, generating a report based on the attribute co-occurrence data structure and the attribute/value pairs in the index, including: identifying the second attribute based on the relationship identified in the attribute co-occurrence data structure; identifying an attribute/value pair that includes the second attribute; and generating the report, including providing access to the event data in the log file using a reference pointer that is mapped to the identified attribute/value pair in the index. 15. The system of claim 8 , wherein the attribute/value pairs represent particular instances of event data.