如何获取PostgreSQL中完整的函数定义脚本？

Got it, let’s tackle this problem head-on. The issue you’re facing—your query returning a truncated function definition without the full header and tail—almost always boils down to either using the wrong system object to pull the definition, hitting character limits in the stored column, or client tool truncation. Here’s how to fix it for the most common databases:

For SQL Server #

If your original query relied on sys.sql_modules or OBJECT_DEFINITION(), note that sys.sql_modules.definition caps at 4000 characters for non-max data types. To grab the full definition, use one of these approaches:

-- Option 1: Convert OBJECT_DEFINITION to a max-length type for full text
SELECT 
  OBJECT_NAME(object_id) AS function_name,
  CAST(OBJECT_DEFINITION(object_id) AS NVARCHAR(MAX)) AS full_definition
FROM sys.objects
WHERE type IN ('FN', 'IF', 'TF') -- Match your function type: scalar, inline TVF, multi-statement TVF
  AND OBJECT_NAME(object_id) = 'YourFunctionName';

-- Option 2: Query sys.all_sql_modules (supports longer definitions natively)
SELECT 
  OBJECT_NAME(object_id) AS function_name,
  definition AS full_definition
FROM sys.all_sql_modules
WHERE object_id = OBJECT_ID('YourSchema.YourFunctionName'); -- Always qualify with schema!

For MySQL #

SHOW CREATE FUNCTION can sometimes truncate output in client tools. Instead, pull directly from information_schema.routines, or adjust your server settings first:

-- Get full definition from information_schema
SELECT 
  ROUTINE_NAME AS function_name,
  ROUTINE_DEFINITION AS full_definition
FROM information_schema.routines
WHERE ROUTINE_SCHEMA = 'YourDatabase'
  AND ROUTINE_NAME = 'YourFunctionName';

-- If you prefer SHOW CREATE FUNCTION, increase max packet size first
SET max_allowed_packet = 1073741824; -- 1GB, tweak based on your function's size
SHOW CREATE FUNCTION YourDatabase.YourFunctionName;

For PostgreSQL #

Avoid querying pg_proc.prosrc directly—it only stores the function body, not the header. Use the dedicated pg_get_functiondef() function instead:

SELECT 
  proname AS function_name,
  pg_get_functiondef(oid) AS full_definition
FROM pg_proc
WHERE proname = 'YourFunctionName'
  AND pronamespace = (SELECT oid FROM pg_namespace WHERE nspname = 'YourSchema');

For Oracle #

Skip querying user_source (which splits the definition into rows) and use dbms_metadata.get_ddl() to get the full, properly formatted definition:

SELECT 
  dbms_metadata.get_ddl('FUNCTION', 'YourFunctionName', 'YourSchema') AS full_definition
FROM dual;

Quick Troubleshooting Checks #

• Client tool limits: Tools like older SSMS versions or MySQL Workbench often truncate long text by default. Look for settings to "show full text" or increase column display limits.
• Schema/database qualification: Always specify the schema/database in your query—you might be pulling a different function with the same name from another schema.
• Object type match: Make sure you’re filtering for the right function type (e.g., scalar vs. table-valued) in your where clause.

If you’re working with a less common database or have more specifics about your original query/environment, drop those details and we can refine this further!

内容的提问来源于stack exchange，提问作者EricBlair1984