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2.3.2.1 Column Types

Abstract

This section details the public types belonging to the Column class.

2.3.2.1.1 The Column::ArrayType Type

Abstract

This type describes the Column's internal attribute format.

Description.  The attribute storage format can be either fixed or variable.

Enumeration values.  Possible values are shown, along with descriptions, in the following table:

Value Description
ArrayTypeFixed stored as a fixed number of bytes
ArrayTypeShortVar stored as a variable number of bytes; uses 1 byte overhead
ArrayTypeMediumVar stored as a variable number of bytes; uses 2 bytes overhead

The fixed storage format is faster but also generally requires more space than the variable format. The default is ArrayTypeShortVar for Var* types and ArrayTypeFixed for others. The default is usually sufficient.

2.3.2.1.2 The Column::StorageType Type

Abstract

This type describes the storage type used by a Column object.

Description.  The storage type used for a given column can be either in memory or on disk. Columns stored on disk mean that less RAM is required overall but such columns cannot be indexed, and are potentially much slower to access. The default is StorageTypeMemory.

Enumeration values.  Possible values are shown, along with descriptions, in the following table:

Value Description
StorageTypeMemory Store the column in memory
StorageTypeDisk Store the column on disk
2.3.2.1.3 Column::Type

Abstract

Type is used to describe the Column object's data type.

Description.  Data types for Column objects are analogous to the data types used by MySQL. The types Tinyint, Tinyintunsigned, Smallint, Smallunsigned, Mediumint, Mediumunsigned, Int, Unsigned, Bigint, Bigunsigned, Float, and Double (that is, types Tinyint through Double in the order listed in the Enumeration Values table) can be used in arrays.

Enumeration values.  Possible values are shown, along with descriptions, in the following table:

Value Description
Undefined Undefined
Tinyint 1-byte signed integer
Tinyunsigned 1-byte unsigned integer
Smallint 2-byte signed integer
Smallunsigned 2-byte unsigned integer
Mediumint 3-byte signed integer
Mediumunsigned 3-byte unsigned integer
Int 4-byte signed integer
Unsigned 4-byte unsigned integer
Bigint 8-byte signed integer
Bigunsigned 8-byte signed integer
Float 4-byte float
Double 8-byte float
Olddecimal Signed decimal as used prior to MySQL 5.0
Olddecimalunsigned Unsigned decimal as used prior to MySQL 5.0
Decimal Signed decimal as used by MySQL 5.0 and later
Decimalunsigned Unsigned decimal as used by MySQL 5.0 and later
Char A fixed-length array of 1-byte characters; maximum length is 255 characters
Varchar A variable-length array of 1-byte characters; maximum length is 255 characters
Binary A fixed-length array of 1-byte binary characters; maximum length is 255 characters
Varbinary A variable-length array of 1-byte binary characters; maximum length is 255 characters
Datetime An 8-byte date and time value, with a precision of 1 second
Date A 4-byte date value, with a precision of 1 day
Blob A binary large object; see Section 2.3.18, “The NdbBlob Class”
Text A text blob
Bit A bit value; the length specifies the number of bits
Longvarchar A 2-byte Varchar
Longvarbinary A 2-byte Varbinary
Time Time without date
Year 1-byte year value in the range 1901-2155 (same as MySQL)
Timestamp Unix time
Caution

Do not confuse Column::Type with Object::Type.


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