Parse Error Logs by Module

SQL practice question · Hard · Strings · TCS, Infosys

Each raw log line looks like 'timestamp|LEVEL|key=value;key=value;...'. LEVEL can have stray spaces and any letter case. The key=value pairs appear in ANY order, may have spaces around ';', and keys such as 'submodule' must not be confused with 'module'. Consider only ERROR lines that have a module key. Module names are case-insensitive (report them lower-case); a line may have no code key. Return module, error_count (ERROR lines) and distinct_codes (number of different code values among them). Order by error_count DESC, then module.

Table: app_logs

Schema of app_logs
ColumnType
log_idINTEGER
rawTEXT
Sample rows of app_logs
log_idraw
12026-03-01 10:00:01|ERROR|module=billing;code=504;user=88
22026-03-01 10:00:05|INFO|module=billing;user=12
32026-03-01 10:01:00|ERROR|code=500;module=billing;user=7
42026-03-01 10:02:00|ERROR|module=auth;code=401
52026-03-01 10:03:00|WARN|module=auth;code=429
62026-03-01 10:04:00|ERROR|user=3;module=billing;code=504
72026-03-01 10:05:00|ERROR|module=search;code=503;user=1
Expected output on the sample data
moduleerror_countdistinct_codes
billing32
auth11
search11

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