1 Database Export 1 Database Export
2 =============== 2 ===============
3 3
4 perf tool's python scripting engine: 4 perf tool's python scripting engine:
5 5
6 tools/perf/util/scripting-engines/trac 6 tools/perf/util/scripting-engines/trace-event-python.c
7 7
8 supports scripts: 8 supports scripts:
9 9
10 tools/perf/scripts/python/export-to-sq 10 tools/perf/scripts/python/export-to-sqlite.py
11 tools/perf/scripts/python/export-to-po 11 tools/perf/scripts/python/export-to-postgresql.py
12 12
13 which export data to a SQLite3 or PostgreSQL d 13 which export data to a SQLite3 or PostgreSQL database.
14 14
15 The export process provides records with uniqu 15 The export process provides records with unique sequential ids which allows the
16 data to be imported directly to a database and 16 data to be imported directly to a database and provides the relationships
17 between tables. 17 between tables.
18 18
19 Over time it is possible to continue to expand 19 Over time it is possible to continue to expand the export while maintaining
20 backward and forward compatibility, by followi 20 backward and forward compatibility, by following some simple rules:
21 21
22 1. Because of the nature of SQL, existing tabl 22 1. Because of the nature of SQL, existing tables and columns can continue to be
23 used so long as the names and meanings (and to 23 used so long as the names and meanings (and to some extent data types) remain
24 the same. 24 the same.
25 25
26 2. New tables and columns can be added, withou 26 2. New tables and columns can be added, without affecting existing SQL queries,
27 so long as the new names are unique. 27 so long as the new names are unique.
28 28
29 3. Scripts that use a database (e.g. exported- 29 3. Scripts that use a database (e.g. exported-sql-viewer.py) can maintain
30 backward compatibility by testing for the pres 30 backward compatibility by testing for the presence of new tables and columns
31 before using them. e.g. function IsSelectable( 31 before using them. e.g. function IsSelectable() in exported-sql-viewer.py
32 32
33 4. The export scripts themselves maintain forw 33 4. The export scripts themselves maintain forward compatibility (i.e. an existing
34 script will continue to work with new versions 34 script will continue to work with new versions of perf) by accepting a variable
35 number of arguments (e.g. def call_return_tabl 35 number of arguments (e.g. def call_return_table(*x)) i.e. perf can pass more
36 arguments which old scripts will ignore. 36 arguments which old scripts will ignore.
37 37
38 5. The scripting engine tests for the existenc 38 5. The scripting engine tests for the existence of script handler functions
39 before calling them. The scripting engine can 39 before calling them. The scripting engine can also test for the support of new
40 or optional features by checking for the exist 40 or optional features by checking for the existence and value of script global
41 variables. 41 variables.
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