Fix: Ensure unique index names for pgvector knowledge tables (#19672)

Co-authored-by: crazywoola <427733928@qq.com>

api/core/rag/datasource/vdb/pgvector/pgvector.py

+import hashlib
 import json
 import logging
 import uuid
 """
 
 SQL_CREATE_INDEX = """
-CREATE INDEX IF NOT EXISTS embedding_cosine_v1_idx ON {table_name}
+CREATE INDEX IF NOT EXISTS embedding_cosine_v1_idx_{index_hash} ON {table_name}
 USING hnsw (embedding vector_cosine_ops) WITH (m = 16, ef_construction = 64);
 """
 
 SQL_CREATE_INDEX_PG_BIGM = """
-CREATE INDEX IF NOT EXISTS bigm_idx ON {table_name}
+CREATE INDEX IF NOT EXISTS bigm_idx_{index_hash} ON {table_name}
 USING gin (text gin_bigm_ops);
 """
 
         super().__init__(collection_name)
         self.pool = self._create_connection_pool(config)
         self.table_name = f"embedding_{collection_name}"
+        self.index_hash = hashlib.md5(self.table_name.encode()).hexdigest()[:8]
         self.pg_bigm = config.pg_bigm
 
     def get_type(self) -> str:
                 # PG hnsw index only support 2000 dimension or less
                 # ref: https://github.com/pgvector/pgvector?tab=readme-ov-file#indexing
                 if dimension <= 2000:
-                    cur.execute(SQL_CREATE_INDEX.format(table_name=self.table_name))
+                    cur.execute(SQL_CREATE_INDEX.format(table_name=self.table_name, index_hash=self.index_hash))
                 if self.pg_bigm:
-                    cur.execute("CREATE EXTENSION IF NOT EXISTS pg_bigm")
-                    cur.execute(SQL_CREATE_INDEX_PG_BIGM.format(table_name=self.table_name))
+                    cur.execute(SQL_CREATE_INDEX_PG_BIGM.format(table_name=self.table_name, index_hash=self.index_hash))
             redis_client.set(collection_exist_cache_key, 1, ex=3600)