database: Add builds only if one of their outputs is new.

* Makefile.am (dist_sql_DATA): Add 'src/sql/upgrade-4.sql'.
* src/cuirass/database.scm (db-add-output): New procedure.
(db-add-build): Call DB-ADD-OUTPUT, rollback the transaction and return #f if
DB-ADD-OUTPUT returned an empty list.
* src/schema.sql (Outputs): Set 'path' as primary key, instead of 'derivation,
name'.
* src/sql/upgrade-4.sql: New file with SQL queries to upgrade the database.
* tests/database.scm (make-dummy-build): Use the #:OUTPUTS key.  Get default
OUTPUTS to depend on DRV.
("db-add-build-with-fixed-output"): New test.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/sql/upgrade-4.sql b/src/sql/upgrade-4.sql
new file mode 100644
index 0000000..e567f03
--- /dev/null
+++ b/src/sql/upgrade-4.sql
@@ -0,0 +1,18 @@
+BEGIN TRANSACTION;
+
+ALTER TABLE Outputs RENAME TO tmp_Outputs;
+
+CREATE TABLE Outputs (
+  derivation TEXT NOT NULL,
+  name TEXT NOT NULL,
+  path TEXT NOT NULL PRIMARY KEY,
+  FOREIGN KEY (derivation) REFERENCES Builds (derivation)
+);
+
+INSERT OR IGNORE INTO Outputs (derivation, name, path)
+SELECT derivation, name, path
+FROM tmp_Outputs;
+
+DROP TABLE tmp_Outputs;
+
+COMMIT;