Make infinity able to cal embedding sim only. (#4644)

### What problem does this PR solve?


### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/utils/infinity_conn.py

@@ -273,9 +273,22 @@ class InfinityConnection(DocStoreConnection):
         for essential_field in ["id"]:
             if essential_field not in selectFields:
                 selectFields.append(essential_field)
+        score_func = ""
+        score_column = ""
+        for matchExpr in matchExprs:
+            if isinstance(matchExpr, MatchTextExpr):
+                score_func = "score()"
+                score_column = "SCORE"
+                break
+        if not score_func:
+            for matchExpr in matchExprs:
+                if isinstance(matchExpr, MatchDenseExpr):
+                    score_func = "similarity()"
+                    score_column = "SIMILARITY"
+                    break
         if matchExprs:
-            for essential_field in ["score()", PAGERANK_FLD]:
-                selectFields.append(essential_field)
+            selectFields.append(score_func)
+            selectFields.append(PAGERANK_FLD)
 
         # Prepare expressions common to all tables
         filter_cond = None
@@ -364,7 +377,9 @@ class InfinityConnection(DocStoreConnection):
         self.connPool.release_conn(inf_conn)
         res = concat_dataframes(df_list, selectFields)
         if matchExprs:
-            res = res.sort(pl.col("SCORE") + pl.col(PAGERANK_FLD), descending=True, maintain_order=True)
+            res = res.sort(pl.col(score_column) + pl.col(PAGERANK_FLD), descending=True, maintain_order=True)
+            if score_column and score_column != "SCORE":
+                res = res.rename({score_column: "SCORE"})
         res = res.limit(limit)
         logger.debug(f"INFINITY search final result: {str(res)}")
         return res, total_hits_count