为什么我的PostgreSQL“真实”数据被四舍五入？

Question

I have a table with a column named total having the real data type.

But I'm finding that this column is being rounded when I query its value, as illustrated in the following:

SELECT total FROM data WHERE id='xe54g';
 total 
---------
  105861

UPDATE data SET total=105860.5 WHERE id='xe54g';        
UPDATE 1

SELECT total FROM data WHERE id='xe54g';
 total 
---------
  105860

UPDATE data SET total=105860.7 WHERE id='xe54g';        
UPDATE 1

SELECT total FROM data WHERE id='xe54g';
 total 
---------
  105861

\d+ data
   Column  |  Type | Collation | Nullable |  Default  | Storage  | Stats target | Description 
-----------+-------+-----------+----------+-----------+----------+--------------+-------------
 total     | real  |           |          | 0         | plain    |              | 

How do I get it to return the full precision? I'm using PG 11.1.

Answer 1

You can get the full precision by setting

extra_float_digits = 3

Then PostgreSQL will also display decimal digits that may contain rounding errors.

Note that real has a low number of significant digits. You'd be happier if you used double precision .