How LOB data is stored in SQL Server?

In SQL Server, Large Object data is stored in special LOB data pages that live in separate LOB data allocation units. Those pages are of type 3 (TEXT_MIX_PAGE). Any partition of any table or index that holds a column with a LOB data type automatically receives a LOB_DATA allocation unit.

Is NVARCHAR a LOB?

NVARCHAR(MAX) is a LOB. Any other NVARCHAR is not LOB.

What is data type in SQL Server?

In SQL Server, each column, local variable, expression, and parameter has a related data type. A data type is an attribute that specifies the type of data that the object can hold: integer data, character data, monetary data, date and time data, binary strings, and so on.

Is varchar max LOB?

SELECT REPLICATE(CONVERT(VARCHAR(MAX), ‘x’), 8001); The query results here show that pages were written to both “IN_ROW_DATA” and “LOB_DATA” pages. Note that the “in row” record is very small. When VARCHAR(MAX) exceeds 8,000 characters, the pointer is stored “in row”, and the string is stored in “LOB” pages.

What is an LOB column?

LOB columns are columns that contain large amounts of data either in Binary Format (BLOBs) or Character Format (CLOBs). Tables with LOB data can be processed like other data types, and LOB data can be edited and browsed like other data. LOB columns are displayed in Native or Non-Native mode.

What are the most common data types in SQL?

Commonly used SQL Server Data Types

• INT.
• VARCHAR, NVARCHAR.
• DATETIME.
• DECIMAL, FLOAT.
• BIT.

Should I always use varchar?

Not using varchar with specific string length confuses the future programmers. It will be difficult for them to figure out the expected size of the string and may end in validation mistakes.

What is a LOB index?

A LOB is simply a pointer. It points to an index. the index points to the chunks that make up the LOB. Hence when you create a LOB, you will always get a lob index created (to find the chunks for the lob fast) and a segment that holds the lob data (chunks).

What are the types of LOB?

LOB (large objects) data types, such as CLOB, NCLOB, and BLOB, are used to store a large amount of data, such as text documents and images. The maximum size for a LOB is 2 GB. The BLOB data type is used to store large amounts of binary data. BLOB values can be converted to VARBINARY.