Character types (char, varchar, text) in PostgreSQL - Step-by-Step Execution

Concept Flow - Character types (char, varchar, text)

Start: Define column type

↓

Choose char(n)

↓

Choose varchar(n)

↓

Choose text

↓

Store data accordingly

↓

Retrieve data

↓

Trim spaces for char(n) if needed

↓

End

The flow shows choosing between char, varchar, and text types, storing data, and how data is handled on retrieval.

Execution Sample

PostgreSQL

CREATE TABLE example (
  fixed_char CHAR(5),
  var_char VARCHAR(5),
  long_text TEXT
);

INSERT INTO example VALUES ('abc', 'abc', 'abc');
SELECT * FROM example;

Creates a table with char, varchar, and text columns, inserts 'abc' into each, then selects all rows.

Execution Table

Step	Action	Input Value	Stored Value	Notes
1	Create table with CHAR(5), VARCHAR(5), TEXT columns	N/A	Table schema created	Defines column types
2	Insert 'abc' into CHAR(5)	'abc'	'abc '	CHAR pads with spaces to length 5
3	Insert 'abc' into VARCHAR(5)	'abc'	'abc'	VARCHAR stores exact length up to 5
4	Insert 'abc' into TEXT	'abc'	'abc'	TEXT stores exact length, no limit here
5	Select all rows	N/A	'abc ', 'abc', 'abc'	Retrieves stored values
6	Trim CHAR(5) value on retrieval if needed	'abc '	'abc'	Spaces can be trimmed for display
7	End	N/A	N/A	Execution complete

💡 All values inserted and retrieved according to their type rules

Variable Tracker

Variable	Start	After Insert	After Select	Final
fixed_char	NULL	'abc '	'abc '	'abc' (trimmed for display)
var_char	NULL	'abc'	'abc'	'abc'
long_text	NULL	'abc'	'abc'	'abc'

Key Moments - 3 Insights

Why does CHAR(5) store 'abc' as 'abc ' with spaces?

CHAR(n) always stores exactly n characters, padding with spaces if input is shorter, as shown in execution_table step 2.

Does VARCHAR(5) pad spaces like CHAR(5)?

No, VARCHAR stores only the input length up to the max, no padding, as seen in step 3.

Is there a length limit for TEXT type?

TEXT has no practical length limit in PostgreSQL, it stores the full input as is, shown in step 4.

Visual Quiz - 3 Questions

Look at the execution_table, what is the stored value for CHAR(5) after inserting 'abc'?

A 'abc '

B 'abc'

C 'abc '

D 'abc\0\0'

💡 Hint

Check execution_table row 2 under Stored Value column

At which step does VARCHAR(5) store the exact input length without padding?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at execution_table row 3 for VARCHAR behavior

If you insert 'abcdef' into VARCHAR(5), what happens?

A Stores 'abcdef' fully

B Stores 'abcde' truncated

C Insertion fails due to length limit

D Stores 'abc ' padded

💡 Hint

VARCHAR(5) max length is 5, check PostgreSQL behavior for exceeding length

Concept Snapshot

Character types in PostgreSQL:
- CHAR(n): fixed length, pads spaces if shorter
- VARCHAR(n): variable length, max n characters, no padding
- TEXT: variable length, unlimited size
Use CHAR for fixed size, VARCHAR for limited variable size, TEXT for large text data.

Full Transcript

This visual execution shows how PostgreSQL stores and retrieves data using character types CHAR, VARCHAR, and TEXT. CHAR(n) always stores fixed length by padding spaces if input is shorter. VARCHAR(n) stores variable length strings up to n characters without padding. TEXT stores variable length strings with no practical limit. The example creates a table with these types, inserts 'abc' into each, and selects the data. The CHAR column stores 'abc' padded with two spaces to length 5, VARCHAR stores 'abc' exactly, and TEXT stores 'abc' exactly. On retrieval, CHAR values can be trimmed for display. This helps beginners understand how these types behave differently in storage and retrieval.