Linking git log file to JIRA issues

[Mohammad J. Ahmad]

I am in the process of extracting certain software features for research purposes. Almost 60% of the projects i want to study are hosted on github, with JIRA as the bug tracking system. 

For each project, i create a log file thourhg git using something like:

git log --stat --all > log.txt 

this shows all commits made to the repository. Normally, each commit made has a message mentionning a JIRA issue ID, neverthekess tho, commits and discussions made on JIRA don't show on the git log file. This makes no sense, all changed made through JIRA to the source code should be shown in the log file, correct ? As if something is not linked, and that was the case with all of the projects i am studying. Is there a way to either export all JIRA issues (not just a max of 1,000 with limited fields), and include all communications and discussions for each commit made, with a git commit ID included  ?

Is there a way to generate the git log file differently to include ALL JIRA commits, messages, and communications ?