pointer item

pointer item


pid Index Level port
Syntax
Category Definitions
Type Definition
Description Pointer items are internal file "placekeepers", which point to the frame where the actual data resides.

Items are normally stored in a file with a few bytes of overhead data, followed by the item-id, followed by the attributes, and then an end-of-item indicator.

If the size of the item exceeds a given length (860 bytes for a 1-k frame system, 1720 bytes for a 2-k frame system), then D3 uses a "pointer item" in the file, which contains the overhead data, the item-id, and a frame address which points to where the attribute values are stored, so most of the item's data will reside outside of the file's primary filespace.

This method increases performance during most Access functions, as reading pointer items is considerably more efficient than reading the entire item during such common functions such as LIST or SORT.

A data file may be declared (at create-time) to contain all pointer items, forcing every entry to be a pointer item. There is no converse non-pointer item declaration.
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See Also file-defining item istat item update-prot save f.modulo T-verify error message explanations set-ovf-local FlashBASIC release notes master dictionary u222d list-file-access
Example
Warnings
Compatibility
pid Index Level port