CODEWITHSUNDEEP
postgresqlpostgresql-8.4
Skartt
Skartt

Reputation: 591

Column type inconsistency: character varying and character varying(30)

For my application, I created a SQL file patch to add a column user_name to an existant table :

CREATE OR REPLACE FUNCTION add_col(
  _tbl VARCHAR,  -- Table                                                                                                                                                                                      
  _col VARCHAR,  -- Column to add                                                                                                                                                                              
  _type regtype -- Type of that column                                                                                                                                                                         
) RETURNS BOOL AS $$
BEGIN
  -- Returns true if column has been added; false otherwise.                                                                                                                                                   
  IF EXISTS (SELECT DISTINCT column_name
             FROM information_schema.columns
             WHERE table_schema LIKE current_schema and table_name LIKE _tbl and column_name LIKE _col
            )
  THEN
     -- Column already exists in that table of that schema: do nothing.                                                                                                                                        
     RETURN false;
  END IF;

  -- Add column                                                                                                                                                                                                
  EXECUTE 'ALTER TABLE ' || _tbl || ' ADD COLUMN ' || _col || ' ' || _type;

  RETURN true;
END; $$ language 'plpgsql';

SELECT add_col('ack_event', 'user_name', 'VARCHAR(30)');

If I execute that and do a SELECT to display ack_event content, we see that the column user_name is added but with the "character varying" type: 

| id     | user_name         |
| bigint | character varying |
|--------+-------------------+
|        |                   |

However if the ack_event column is created directly with the user_name column, the type of user_name is "character_varying(30)" : 

CREATE TABLE ACK_EVENT(
    ID int8 not null,
    USER_NAME VARCHAR(30),

     CONSTRAINT PK_ACK_EVENT PRIMARY KEY (ID)
);

Result:

| id     | user_name             |
| bigint | character varying(30) |
|--------+-----------------------+
|        |                       |

Why is there this inconsistency ? Is there a way to correct it and have character varying (30) in both cases ?

Upvotes: 1

Views: 384

Answers (1)

Hambone
Hambone

Reputation: 16377

This may introduce some validation issues, but if you change the datatype of _type from regtype to a text datatype, I think it will input your DDL much more literally:

CREATE OR REPLACE FUNCTION add_col(
  _tbl VARCHAR,
  _col VARCHAR,
  _type text -- this was previously regtype
) RETURNS varchar AS $$

Upvotes: 1

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