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Diffstat (limited to 'doc/FAQ')
| -rw-r--r-- | doc/FAQ | 14 |
1 files changed, 6 insertions, 8 deletions
@@ -811,19 +811,17 @@ Type Internal Name Notes "char" char 1 character CHAR(#) bpchar blank padded to the specified fixed length VARCHAR(#) varchar size specifies maximum length, no padding -TEXT text length limited only by maximum row length -BYTEA bytea variable-length array of bytes +TEXT text no specific upper limit on length +BYTEA bytea variable-length byte array (null-safe) You will see the internal name when examining system catalogs and in some error messages. The last four types above are "varlena" types (i.e., the first four - bytes are the length, followed by the data). char(#) allocates the - maximum number of bytes no matter how much data is stored in the - field. text, varchar(#), and bytea all have variable length on the - disk, and because of this, there is a small performance penalty for - using them. Specifically, the penalty is for access to all columns - after the first column of this type. + bytes on disk are the length, followed by the data). Thus the actual + space used is slightly greater than the declared size. However, these + data types are also subject to compression or being stored out-of-line + by TOAST, so the space on disk might also be less than expected. 4.16.1) How do I create a serial/auto-incrementing field? |