Initial implementation of pgvector and Oracle 26ai vector search demo

Three FastAPI backends comparing PostgreSQL/pgvector and Oracle 26ai for
semantic image search using CLIP embeddings: Python-side embedding for both
databases, plus Oracle in-database embedding via VECTOR_EMBEDDING(CLIP_TXT).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

oravector-demo/backend/main_oracle_indb.py

@@ -0,0 +1,55 @@
+import os
+from fastapi import FastAPI, Query
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import FileResponse
+from dotenv import load_dotenv
+from db_oracle import get_connection_indb
+
+load_dotenv()
+
+PHOTOS_DIR = os.getenv("PHOTOS_DIR")
+
+app = FastAPI()
+app.add_middleware(CORSMiddleware, allow_origins=["*"], allow_methods=["*"], allow_headers=["*"])
+
+@app.get("/search")
+def search(q: str = Query(...), limit: int = Query(12)):
+    conn = get_connection_indb()
+    cur = conn.cursor()
+    cur.execute(
+        """
+        SELECT filename,
+               1 - VECTOR_DISTANCE(
+                       foto_vek,
+                       VECTOR_EMBEDDING(CLIP_TXT USING :q AS data),
+                       COSINE
+                   ) AS score
+        FROM VECTOR.FOTO_VEKTOR
+        ORDER BY VECTOR_DISTANCE(
+                     foto_vek,
+                     VECTOR_EMBEDDING(CLIP_TXT USING :q AS data),
+                     COSINE
+                 )
+        FETCH FIRST :lim ROWS ONLY
+        """,
+        {"q": q, "lim": limit},
+    )
+    rows = cur.fetchall()
+    cur.close()
+    conn.close()
+    return [{"filename": r[0], "score": round(r[1], 4)} for r in rows]
+
+@app.get("/stats")
+def stats():
+    conn = get_connection_indb()
+    cur = conn.cursor()
+    cur.execute("SELECT COUNT(*) FROM VECTOR.FOTO_VEKTOR")
+    count = cur.fetchone()[0]
+    cur.close()
+    conn.close()
+    return {"count": count}
+
+@app.get("/photos/{filename}")
+def get_photo(filename: str):
+    path = os.path.join(PHOTOS_DIR, filename)
+    return FileResponse(path, media_type="image/jpeg")