execute_hg_select_sql

Query data from Hologres databases using SELECT SQL statements to retrieve specific information for analysis and decision-making.

Instructions

Execute SELECT SQL to query data from Hologres database.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`query`	Yes	The (SELECT) SQL query to execute in Hologres database.

Implementation Reference

src/hologres_mcp_server/utils.py:48-79 (handler)

Core handler function that executes the SQL query for the execute_hg_select_sql tool (and others). Connects to Hologres database, executes the query, formats SELECT results as CSV-like text with columns and rows.

def handle_call_tool(tool_name, query, serverless = False):
    """Handle callTool method."""
    config = get_db_config()
    try:
        with connect_with_retry() as conn:
            with conn.cursor() as cursor:

                # 特殊处理 serverless computing 查询
                if serverless:
                    cursor.execute("set hg_computing_resource='serverless'")
                
                # Execute the query
                cursor.execute(query)
                
                # 特殊处理 ANALYZE 命令
                if tool_name == "gather_hg_table_statistics":
                    return f"Successfully {query}"
                
                # 处理其他有返回结果的查询
                if cursor.description:  # SELECT query
                    columns = [desc[0] for desc in cursor.description]
                    rows = cursor.fetchall()
                    result = [",".join(map(str, row)) for row in rows]
                    return "\n".join([",".join(columns)] + result)
                elif tool_name == "execute_dml_sql":  # Non-SELECT query
                    row_count = cursor.rowcount
                    return f"Query executed successfully. {row_count} rows affected."
                else:
                    return "Query executed successfully"
    except Exception as e:
        return f"Error executing query: {str(e)}"

src/hologres_mcp_server/server.py:347-360 (registration)

Registration of the execute_hg_select_sql tool in the MCP server's list_tools() function, including name, description, and input schema.

Tool(
    name="execute_hg_select_sql",
    description="Execute SELECT SQL to query data from Hologres database.",
    inputSchema={
        "type": "object",
        "properties": {
            "query": {
                "type": "string",
                "description": "The (SELECT) SQL query to execute in Hologres database."
            }
        },
        "required": ["query"]
    }
),

src/hologres_mcp_server/server.py:552-557 (handler)

Specific dispatching and input validation logic for the execute_hg_select_sql tool within the call_tool handler, ensuring it's a SELECT query before passing to execution utility.

if name == "execute_hg_select_sql":
    query = arguments.get("query")
    if not query:
        raise ValueError("Query is required")
    if not re.match(r"^\s*WITH\s+.*?SELECT\b", query, re.IGNORECASE) and not re.match(r"^\s*SELECT\b", query, re.IGNORECASE):
        raise ValueError("Query must be a SELECT statement or start with WITH followed by a SELECT statement")

src/hologres_mcp_server/utils.py:8-26 (helper)

Helper function used by the handler to establish a reliable database connection to Hologres with retries.

def connect_with_retry(retries=3):
    attempt = 0
    err_msg = ""
    while attempt <= retries:
        try:
            config = get_db_config()
            conn = psycopg.connect(**config)
            conn.autocommit = True
            with conn.cursor() as cursor:
                cursor.execute("SELECT 1;")
                cursor.fetchone()
            return conn
        except psycopg.Error as e:
            err_msg = f"Connection failed: {e}"
            attempt += 1
            if attempt <= retries:
                print(f"Retrying connection (attempt {attempt + 1} of {retries + 1})...")
                time.sleep(5)  # 等待 2 秒后再次尝试连接
    raise psycopg.Error(f"Failed to connect to Hologres database after retrying: {err_msg}")

Hologres MCP Server