db/sqlc: kvstores schemas & queries

In this commit, we define the schemas and queries that are needed to
implement the firewalldb's KVStores in SQL.

Author: ellemouton

db/migrations.go

@@ -22,7 +22,7 @@ const (
 	// daemon.
 	//
 	// NOTE: This MUST be updated when a new migration is added.
-	LatestMigrationVersion = 2
+	LatestMigrationVersion = 3
 )
 
 // MigrationTarget is a functional option that can be passed to applyMigrations

db/sqlc/kvstores.sql.go

@@ -0,0 +1,7 @@
+-- Drop indexes first.
+DROP INDEX IF EXISTS kvstores_lookup_idx;
+
+-- Drop tables in reverse dependency order.
+DROP TABLE IF EXISTS kvstores;
+DROP TABLE IF EXISTS features;
+DROP TABLE IF EXISTS rules;

db/sqlc/migrations/000003_kvstores.down.sql

@@ -0,0 +1,55 @@
+-- rules holds the unique names of the various rules that are used
+-- known to lit and used by the firewall db.
+CREATE TABLE IF NOT EXISTS rules (
+    -- The auto incrementing primary key.
+    id INTEGER PRIMARY KEY,
+
+    -- The unique name of the rule.
+    name TEXT NOT NULL UNIQUE
+);
+
+-- features holds the unique names of the various features that
+-- kvstores can be associated with.
+CREATE TABLE IF NOT EXISTS features (
+    -- The auto incrementing primary key.
+    id INTEGER PRIMARY KEY,
+
+    -- The unique name of the feature.
+    name TEXT NOT NULL UNIQUE
+);
+
+-- kvstores houses key-value pairs under various namespaces determined
+-- by the rule name, session ID, and feature name.
+CREATE TABLE IF NOT EXISTS kvstores (
+    -- The auto incrementing primary key.
+    id INTEGER PRIMARY KEY,
+
+    -- Whether this record is part of the permanent store.
+    -- If false, it will be deleted on start-up.
+    perm BOOLEAN NOT NULL,
+
+    -- The rule that this kv_store belongs to.
+    -- If only the rule name is set, then this kv_store is a global
+    -- kv_store.
+    rule_id BIGINT REFERENCES rules(id) NOT NULL,
+
+    -- The session ID that this kv_store belongs to.
+    -- If this is set, then this kv_store is a session-specific
+    -- kv_store for the given rule.
+    session_id BIGINT REFERENCES sessions(id) ON DELETE CASCADE,
+
+    -- The feature name that this kv_store belongs to.
+    -- If this is set, then this kv_store is a feature-specific
+    -- kvstore under the given session ID and rule name.
+    -- If this is set, then session_id must also be set.
+    feature_id BIGINT REFERENCES features(id),
+
+    -- The key of the entry.
+    entry_key TEXT NOT NULL,
+
+    -- The value of the entry.
+    value BLOB NOT NULL
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS kvstores_lookup_idx
+    ON kvstores (entry_key, rule_id, perm, session_id, feature_id);