fix: rand() not supported in postgresql (#570)

pandasai/connectors/sql.py

@@ -391,3 +391,25 @@ def __init__(self, config: ConnectorConfig):
             config["password"] = os.getenv("POSTGRESQL_PASSWORD")
 
         super().__init__(config)
+
+    @cache
+    def head(self):
+        """
+        Return the head of the data source that the connector is connected to.
+        This information is passed to the LLM to provide the schema of the data source.
+
+        Returns:
+            DataFrame: The head of the data source.
+        """
+
+        if self.logger:
+            self.logger.log(
+                f"Getting head of {self._config.table} "
+                f"using dialect {self._config.dialect}"
+            )
+
+        # Run a SQL query to get all the columns names and 5 random rows
+        query = self._build_query(limit=5, order="RANDOM()")
+
+        # Return the head of the data source
+        return pd.read_sql(query, self._connection)