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author | Adrian Hunter <adrian.hunter@intel.com> | 2019-05-20 14:37:20 +0300 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2019-06-05 09:47:57 -0300 |
commit | 1159facee97fe184a434db3086604c7572fd7dfa (patch) | |
tree | 5832452365253e21f89cb9a703a200589c74ffb3 /tools/perf/Documentation | |
parent | 003ccdc7165accee073ce261fc670f64cc98d0f7 (diff) | |
download | linux-1159facee97fe184a434db3086604c7572fd7dfa.tar.bz2 |
perf db-export: Add brief documentation
Add brief documentation to explain how the database export maintains
backward and forward compatibility.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190520113728.14389-15-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/Documentation')
-rw-r--r-- | tools/perf/Documentation/db-export.txt | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/tools/perf/Documentation/db-export.txt b/tools/perf/Documentation/db-export.txt new file mode 100644 index 000000000000..52ffccb02d55 --- /dev/null +++ b/tools/perf/Documentation/db-export.txt @@ -0,0 +1,41 @@ +Database Export +=============== + +perf tool's python scripting engine: + + tools/perf/util/scripting-engines/trace-event-python.c + +supports scripts: + + tools/perf/scripts/python/export-to-sqlite.py + tools/perf/scripts/python/export-to-postgresql.py + +which export data to a SQLite3 or PostgreSQL database. + +The export process provides records with unique sequential ids which allows the +data to be imported directly to a database and provides the relationships +between tables. + +Over time it is possible to continue to expand the export while maintaining +backward and forward compatibility, by following some simple rules: + +1. Because of the nature of SQL, existing tables and columns can continue to be +used so long as the names and meanings (and to some extent data types) remain +the same. + +2. New tables and columns can be added, without affecting existing SQL queries, +so long as the new names are unique. + +3. Scripts that use a database (e.g. exported-sql-viewer.py) can maintain +backward compatibility by testing for the presence of new tables and columns +before using them. e.g. function IsSelectable() in exported-sql-viewer.py + +4. The export scripts themselves maintain forward compatibility (i.e. an existing +script will continue to work with new versions of perf) by accepting a variable +number of arguments (e.g. def call_return_table(*x)) i.e. perf can pass more +arguments which old scripts will ignore. + +5. The scripting engine tests for the existence of script handler functions +before calling them. The scripting engine can also test for the support of new +or optional features by checking for the existence and value of script global +variables. |