Database Reference
In-Depth Information
Table 11.2
Data Types in Table Storage
Data Types
Description
Edm.Binary
It deines an array of bytes up to 64 kB in size. Edm stands for
Entity Data Model.
Edm.Boolean
It deines a Boolean value.
Edm.DateTime
It deines a 64-bit value in UTC (coordinated universal time).
Edm.Double
It deines a 64-bit loating point value.
Edm.Guid
It deines a 128-bit globally unique identiier.
Edm.Int32
It deines a 32-bit integer.
Edm.Int64
It deines a 64-bit integer.
Edm.String
It deines a UTF-16-encoded string up to 64 kB in size. UTF
stands for unicode transformation format.
have as many as 50,000 blocks, and the maximum size of a block blob is 200 GB. By using
blocks, a large block blob can be eiciently uploaded to a cloud. he block blob is optimized
for upload and download streaming.
◾
Page Blob
: A page blob consists of 512-byte pages. It is optimized for random read and write
operations. he maximum size of a page blob is 1 TB. When creating a page blob, one needs
to specify the maximum size for the page blob to grow. When writing content to the page
blob, one may write the content to one or more pages. he page blob can be used to imple-
ment NTFS Virtual Hard Drive, which can be mounted by applications on the Windows
Azure platform. he snapshots of the blob can be used for backup. he blob can also be
cached at the nearby data center for fast data access.
Windows Azure Queue Storage
: he Queue storage service is used to store a large number
of messages. he service processes message between applications. It can pass messages from a
Windows Azure Web role to a Windows Azure Worker role. he stored messages can be accessed
from anywhere through network protocols such as HTTP or HTTPS. he messages are processed
in a irst-in irst-out (FIFO) manner. he stored messages can be processed asynchronously. By
default, the size of a message is limited to 8 kB. Although there is no limit on the number of mes-
sages that can be stored in the Queue storage, there is a time limit. Messages will be deleted after
a week in the Queue storage. he life cycle of a message is described below:
◾
A message is added to the Queue storage.
◾
When one application is reading the message, the message is marked as invisible until the
message is deleted or a speciied reading interval is reached.
◾
he message gets deleted if the message stays in the Queue storage for longer than the TTL
or a speciied reading interval is reached.
A message has four main properties that specify the message ID, message visibility, receiving
receipt, and the lifetime of the message.
