Comparison of data types in PostgreSQL, MySQL and SQL Server
Different SQL-based database management systems offer a variety of data types to handle specific types of data, each with its own nuances and variations. PostgreSQL, MySQL, and Microsoft SQL Server, three of the most widely used database systems, share many common data types but also exhibit differences that make each unique. Understanding these differences is crucial for database administrators and developers, especially when migrating between systems or designing applications that may need to be compatible with multiple systems.
This table provides a side-by-side comparison of the major data types across PostgreSQL, MySQL, and SQL Server, covering:
- Numeric Types: From tiny integers to double-precision floating-point numbers, each system offers a range of numeric types tailored to different needs.
- String Types: Fixed-length, variable-length, and large text types differ slightly in syntax and capacity across the systems.
- Date and Time Types: The way dates and times are stored, including timezone support and precision, varies between the systems.
- Boolean Types: Support for boolean data is more consistent, but with minor variations in implementation.
- Binary Types: For storing binary data, different binary data types are provided with various storage capacities.
| Category | PostgreSQL | MySQL | SQL Server |
|---|---|---|---|
| Numeric | smallint: 2 bytes | TINYINT: 1 byte | tinyint: 1 byte |
integer: 4 bytes | SMALLINT: 2 bytes | smallint: 2 bytes | |
bigint: 8 bytes | MEDIUMINT: 3 bytes | int: 4 bytes | |
decimal, numeric: Precision scale | INT: 4 bytes | bigint: 8 bytes | |
real: 4-byte float | BIGINT: 8 bytes | decimal, numeric: Precision scale | |
double precision: 8-byte float | DECIMAL: Precision scale | real: 4-byte float | |
serial: Auto-increment integer | FLOAT: Single-precision float | float: 8-byte float | |
bigserial: Auto-increment bigint | DOUBLE: Double-precision float | ||
| String | char(n): Fixed-length | CHAR(n): Fixed-length | char(n): Fixed-length |
varchar(n): Variable-length | VARCHAR(n): Variable-length | varchar(n): Variable-length | |
text: Unlimited variable-length | TEXT: Unlimited variable-length | text: Up to 2GB (deprecated) | |
| Date & Time | date: Dates only | DATE: Dates only | date: Dates only |
time [without time zone] | TIME: Time only | time: Time only | |
timestamp [without time zone] | DATETIME: Date and time | datetime: Date and time | |
interval: Time intervals | TIMESTAMP: Date and time, timezone | datetime2: Extended datetime | |
time with time zone | datetimeoffset: Date, time, timezone | ||
timestamp with time zone | |||
| Boolean | boolean: true, false, NULL | TINYINT: 0 for false, non-zero | bit: 0 for false, 1 for true |
for true | and NULL | ||
| Binary | bytea: Binary data | BINARY, VARBINARY, BLOB | binary, varbinary, image (deprecated) |
