LOB Descriptors

Use this dialog box to specify storage options for LOB (large object) columns, enabling you to override the default storage options.You can add a LOB descriptor or deleted a selected LOB descriptor.

Columns: Use the shuttle buttons to move the column(s) you want from Available Columns to Selected Columns.

LOB Segment Name: Name for the LOB data segment.

Storage Enabled in Row: Select to enable storage in row. The LOB value is stored in the row (inline) if its length is less than approximately 4000 bytes minus system control information.

Chunk: Number of bytes to be allocated for LOB manipulation. If the value is not a multiple of the database block size, then the database rounds up in bytes to the next multiple. The maximum value is 32768 (32K), which is the largest Oracle Database block size allowed. The default CHUNK size is one Oracle Database block.

Pct Version: Maximum percentage of overall LOB storage space used for maintaining old versions of the LOB. The default value is 10, meaning that older versions of the LOB data are not overwritten until they consume 10% of the overall LOB storage space. You can specify a Pct Version value whether the database is running in manual mode (where it is the default) or automatic undo mode (where Retention is the default). You cannot enter values for both a Pct Version value and the Retention option.

Freepools: Number of groups of free lists for the LOB segment, usually the number of instances in a Real Application Clusters environment or 1 for a single-instance database. You can specify this only if the database is running in automatic undo mode. You cannot enter both a Free Pools value and the Free Lists fields.

Retention: Check to keep old versions of this LOB column. You can only do this if the database is running in automatic undo mode and if you do not specify a Pct Version value.

Cache: Choose how the database should store blocks in the buffer cache.

Storage: Opens the Storage dialog box, where you can define storage options.