Add 'third_party/nix/' from commit 'be66c7a6b24e3c3c6157fd37b86c7203d14acf10'

git-subtree-dir: third_party/nix
git-subtree-mainline: cf8cd640c1
git-subtree-split: be66c7a6b24e3c3c6157fd37b86c7203d14acf10

third_party/nix/src/libstore/schema.sql

@@ -0,0 +1,42 @@
+create table if not exists ValidPaths (
+    id               integer primary key autoincrement not null,
+    path             text unique not null,
+    hash             text not null,
+    registrationTime integer not null,
+    deriver          text,
+    narSize          integer,
+    ultimate         integer, -- null implies "false"
+    sigs             text, -- space-separated
+    ca               text -- if not null, an assertion that the path is content-addressed; see ValidPathInfo
+);
+
+create table if not exists Refs (
+    referrer  integer not null,
+    reference integer not null,
+    primary key (referrer, reference),
+    foreign key (referrer) references ValidPaths(id) on delete cascade,
+    foreign key (reference) references ValidPaths(id) on delete restrict
+);
+
+create index if not exists IndexReferrer on Refs(referrer);
+create index if not exists IndexReference on Refs(reference);
+
+-- Paths can refer to themselves, causing a tuple (N, N) in the Refs
+-- table.  This causes a deletion of the corresponding row in
+-- ValidPaths to cause a foreign key constraint violation (due to `on
+-- delete restrict' on the `reference' column).  Therefore, explicitly
+-- get rid of self-references.
+create trigger if not exists DeleteSelfRefs before delete on ValidPaths
+  begin
+    delete from Refs where referrer = old.id and reference = old.id;
+  end;
+
+create table if not exists DerivationOutputs (
+    drv  integer not null,
+    id   text not null, -- symbolic output id, usually "out"
+    path text not null,
+    primary key (drv, id),
+    foreign key (drv) references ValidPaths(id) on delete cascade
+);
+
+create index if not exists IndexDerivationOutputs on DerivationOutputs(path);