The provenance of query is represented as a single relation that contains the original query results augmented with provenance information.
Perm uses an SQL language extension called SQL-PLE to enable a user to issue provenance queries (e.g. SELECT PROVENANCE).
Perm rewrites provenance queries to normal SQL queries inside PostgresSQL (between parser and planner).
shop
| name | numEmpl |
|---|---|
| Merdies | 3 |
| Joba | 14 |
sales
| sName | itemId |
|---|---|
| Merdies | 1 |
| Merdies | 2 |
| Merdies | 2 |
| Joba | 3 |
| Joba | 3 |
items
| id | price |
|---|---|
| 1 | 100 |
| 2 | 10 |
| 3 | 25 |
SELECT name, sum(price) FROM shop, sales, items WHERE name=sName AND itemID=id GROUP BY name
| name | sum(price) |
|---|---|
| Merdies | 120 |
| Joba | 50 |
SELECT PROVENANCE name, sum(price) FROM shop, sales, items WHERE name=sName AND itemID=id GROUP BY name
| name | sum(price) | pName | pNumEmpl | pSName | pItemId | pId | pPrice |
|---|---|---|---|---|---|---|---|
| Merdies | 120 | Merdies | 3 | Merdies | 1 | 1 | 100 |
| Merdies | 120 | Merdies | 3 | Merdies | 2 | 2 | 10 |
| Merdies | 120 | Merdies | 3 | Merdies | 2 | 2 | 10 |
| Joba | 50 | Joba | 14 | Joba | 3 | 3 | 25 |
| Joba | 50 | Joba | 14 | Joba | 3 | 3 | 25 |