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- 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.
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