* Added note about job ID.

slurm/20190411.Slurm-accounting.md

@@ -55,6 +55,25 @@ and executed while this job is being launched and executed.
 in which various parts of a job can require very different resources.
 See [this documentation](https://slurm.schedmd.com/heterogeneous_jobs.html)
 for more information.)
+The combination of all the job steps constitute the entire job.
+Each job step generates its own record in the SLURM accounting database.
+
+#### Summary on Job ID
+
+A single SLURM job will generate the "master record" which logs the
+overall execution of the job.
+In addition, there can be zero or more extra records generated by the
+"job steps" triggered during the course of that job.
+The master record includes the resource utilization usage (CPU,
+memory, etc) of the child "job steps".
+The master job record is characterized by a plain number in the
+`JobIDRaw` field.
+Further, the `User` field must not be empty.
+
+The rest of this section goes into greater detail of the various
+`JobID`'s.
+
+#### Observed Job ID Patterns
 
 Several regex patterns have observed in the JobID field (from Turing
 accounting):
@@ -101,6 +120,14 @@ This will not be a job array.
 
 * Regexp match : `JobID ~ /^[0-9]+$/`.
 
+From my observation, only simple single-core jobs that do not involve any
+MPI or other fancy stuff (no job array, for example) would not
+generate extra "child records" for job steps in the SLURM accounting
+database.
+
+However, several job records with this type JobID will have no "User" field set.
+These are also not vanilla jobs.
+
 
 #### Array Job