add hotness queries and scaffolding for materializer (#25)

also reformatted some sql

hotness/materializer.go

@@ -0,0 +1,20 @@
+package hotness
+
+import (
+	"github.com/strideynet/bsky-furry-feed/store"
+	"go.uber.org/zap"
+)
+
+type Materializer struct {
+	log   *zap.Logger
+	store *store.PGXStore
+}
+
+func NewMaterializer(
+	log *zap.Logger, store *store.PGXStore,
+) *Materializer {
+	return &Materializer{
+		log:   log,
+		store: store,
+	}
+}

store/migrations/000017_create_post_hotness.down.sql

@@ -0,0 +1 @@
+DROP TABLE post_hotness;

store/migrations/000017_create_post_hotness.up.sql

@@ -0,0 +1,10 @@
+CREATE TABLE post_hotness (
+    uri TEXT PRIMARY KEY,
+    alg TEXT NOT NULL,
+    score REAL NOT NULL,
+    generated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+CREATE INDEX post_hotness_alg_score_idx ON post_hotness (alg, score);
+CREATE INDEX post_hotness_alg_generated_at_idx ON post_hotness (
+    alg, generated_at
+);

store/postgres.go

@@ -703,3 +703,33 @@ func (s *PGXStore) GetPostByURI(ctx context.Context, uri string) (out gen.Candid
 	// TODO: Return a proto type rather than exposing gen.CandidatePost
 	return s.queries.GetPostByURI(ctx, s.pool, uri)
 }
+
+type MaterializeHotPostsOpts struct {
+	RetentionPeriod time.Duration
+	LookbackPeriod  time.Duration
+}
+
+func (s *PGXStore) PurgeAndMaterializeHotPosts(ctx context.Context, opts MaterializeHotPostsOpts) error {
+	tx, err := s.pool.Begin(ctx)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if err := tx.Rollback(ctx); err != nil && !errors.Is(err, pgx.ErrTxClosed) {
+			s.log.Warn("failed to roll back transaction", zap.Error(err))
+		}
+	}()
+
+	if err := s.queries.DeleteOldPostHotness(ctx, tx, pgtype.Interval{Valid: true, Microseconds: opts.RetentionPeriod.Microseconds()}); err != nil {
+		return err
+	}
+
+	if err := s.queries.MaterializeHotPosts(ctx, tx, pgtype.Interval{Valid: true, Microseconds: opts.LookbackPeriod.Microseconds()}); err != nil {
+		return err
+	}
+
+	if err := tx.Commit(ctx); err != nil {
+		return err
+	}
+	return nil
+}