| PostgreSQL | ||
|---|---|---|
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SQL92 defines two primary character types: char and varchar. Postgres supports these types, in addition to the more general text type, which unlike varchar does not require an upper limit to be declared on the size of the field.
Table 8-5. Postgres Character Types
| Character Type | Storage | Recommendation | Description |
|---|---|---|---|
| char | 1 byte | SQL92-compatible | Single character |
| char(n) | (4+n) bytes | SQL92-compatible | Fixed-length blank padded |
| text | (4+x) bytes | Best choice | Variable-length |
| varchar(n) | (4+n) bytes | SQL92-compatible | Variable-length with limit |
There are currently other fixed-length character types. These provide no additional functionality and are likely to be deprecated in the future.
Table 8-6. Postgres Specialty Character Types
| Character Type | Storage | Description |
|---|---|---|
| char2 | 2 bytes | Two characters |
| char4 | 4 bytes | Four characters |
| char8 | 8 bytes | Eight characters |
| char16 | 16 bytes | Sixteen characters |
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