Restructure db schema

The "commit_links" table is now called "commit_edges".

There is now a "metrics" table that run measurements have a foreign key
to. This provides canonical metric metadata and will speed up the
initial graph page (before any real data arrives). For now, it will be
overwritten with each new run, but more nuanced config options may be
added later.

migrations/20230830194148_metric_index.sql

@@ -1,2 +0,0 @@
-CREATE INDEX idx_run_measurements_metric
-ON run_measurements (metric);

migrations/20231023204335_moar_index.sql

@@ -1,5 +0,0 @@
-CREATE INDEX idx_commits_hash_reachable
-ON commits (hash, reachable);
-
-CREATE INDEX idx_commit_links_child_parent
-ON commit_links (child, parent);

migrations/20240513132200_init.sql

@@ -9,23 +9,38 @@ CREATE TABLE commits (
     new            INT  NOT NULL DEFAULT 1
 ) STRICT;
 
-CREATE TABLE commit_links (
+CREATE INDEX idx_commits_hash_reachable
+ON commits (hash, reachable);
+
+CREATE TABLE commit_edges (
     child  TEXT NOT NULL,
     parent TEXT NOT NULL,
 
     PRIMARY KEY (parent, child),
     FOREIGN KEY (parent) REFERENCES commits (hash) ON DELETE CASCADE,
-    FOREIGN KEY (child)  REFERENCES commits (hash) ON DELETE CASCADE
+    FOREIGN KEY (child) REFERENCES commits (hash) ON DELETE CASCADE
 ) STRICT;
 
+CREATE INDEX idx_commit_edges_parent_child
+ON commit_edges (parent, child);
+
+CREATE INDEX idx_commit_edges_child_parent
+ON commit_edges (child, parent);
+
 CREATE TABLE refs (
     name    TEXT NOT NULL PRIMARY KEY,
     hash    TEXT NOT NULL,
-    tracked INT NOT NULL DEFAULT 0,
+    tracked INT  NOT NULL DEFAULT 0,
 
     FOREIGN KEY (hash) REFERENCES commits (hash) ON DELETE CASCADE
 ) STRICT;
 
+CREATE TABLE metrics (
+    name      TEXT NOT NULL PRIMARY KEY,
+    unit      TEXT,
+    direction INT
+) STRICT;
+
 CREATE TABLE runs (
     id           TEXT NOT NULL PRIMARY KEY,
     hash         TEXT NOT NULL,
@@ -46,16 +61,20 @@ CREATE TABLE run_measurements (
     unit      TEXT,
 
     PRIMARY KEY (id, metric),
-    FOREIGN KEY (id) REFERENCES runs (id) ON DELETE CASCADE
+    FOREIGN KEY (id) REFERENCES runs (id) ON DELETE CASCADE,
+    FOREIGN KEY (metric) REFERENCES metrics (name) ON UPDATE CASCADE ON DELETE CASCADE
 ) STRICT;
 
+CREATE INDEX idx_run_measurements_metric_id_value
+ON run_measurements (metric, id, value);
+
 CREATE TABLE run_output (
     id     TEXT NOT NULL,
-    idx    INT  NOT NULL,
+    line   INT  NOT NULL,
     source INT  NOT NULL,
     text   TEXT NOT NULL,
 
-    PRIMARY KEY (id, idx),
+    PRIMARY KEY (id, line),
     FOREIGN KEY (id) REFERENCES runs (id) ON DELETE CASCADE
 ) STRICT;
 
@@ -67,11 +86,5 @@ CREATE TABLE queue (
     FOREIGN KEY (hash) REFERENCES commits (hash) ON DELETE CASCADE
 ) STRICT;
 
-CREATE INDEX idx_commit_links_parent_child
-ON commit_links (parent, child);
-
 CREATE INDEX idx_queue_priority_date_hash
 ON queue (priority DESC, unixepoch(date) DESC, hash ASC);
-
-CREATE INDEX idx_run_measurements_metric_id_value
-ON run_measurements (metric, id, value);