item Definition/General, tcl.item Verb: Access/TCL, item Definition/General

item

Command item Definition/General
Applicable release versions: AP, R83
Category General (155)
Description the fundamental directly accessable aggregation of data in Pick.

An item may be composed of one or more attributes, which may be composed of one or more values, which may in turn be composed of one or more subvalues.

Each item is statistically "hashed" to a group within a file based on the content and length of the item-id, or key to the item.
Syntax
Options
Example
Purpose
Related hashing
value
sub-value
item-id
attribute
access.list-item

tcl.item

Command tcl.item Verb: Access/TCL
Applicable release versions: AP, R83, AP 6.0
Category TCL (746)
Description outputs the base fid of the group to which the specified item-id "hashes", and a list of all item-id's that are currently "hashed" to the same group.

Also displayed is each items' (hexadecimal) byte count field, a count of the total number of items in the group, the total number of bytes, the total number of "full" frames, and the number of bytes used in the "last" frame of the group.

If the given item-id is not found, the group to which it would hash is displayed.

Case sensitivity is an issue in the hashing algorithm used by the Pick system. If a file has a "d-pointer" type of "ds", item-ids are case-sensitive. This means two things: 1, that the item-ids "dog" and "DOG" are treated as two separate items and 2) they would most likely hash to different groups (unless, of course, the file has a modulo of 1). If case sensitivity is "off", "dog" and "DOG" are the same thing, and there can only be one dog. See the "case", "case-on", and "case-off" verbs, and the topic of "file-defining items".

As of AP release 6.0.0, a new feature has been added to the display of items in a group. In the columns between the address and the byte size, three possible letters may appear. They have the following meanings:

B Binary item. This normally occurs with Pick/BASIC object code found in the dictionary level of source files.

F File pointer. This occurs only with "d-pointers".

P Means that this is a "pointer" (indirect) item. This occurs when a file is designated as having a "dp" in its "d-pointer", or when the item size passes approximately eighty percent of the frame size on the system. (See the "what" command for determining frame size).
Syntax item file.reference itemlist* {(options}
Options n Activates nopage function on output to the terminal.

p Directs output to system printer, via the Spooler.

s Suppresses output of item-ids'.
Example
item testfile stuff
stuff
item not found
320710.0000     01BC  pc.v
1 items 444 bytes 0/444 frames in group 320710

This example illustrates the effect of not finding the item, yet showing the 
group to which the item would hash if it were there.
Purpose
Related tcl.group
tcl.itemlist*
tcl.case-off
tcl.case
file.defining.items
modulo.def
access.istat
access.hash-test
tcl.create-file
tcl.what
pointer.item

item

Command item Definition/General
Applicable release versions: AP, R83
Category General (155)
Description the fundamental directly accessable aggregation of data in Pick.

An item may be composed of one or more attributes, which may be composed of one or more values, which may in turn be composed of one or more subvalues.

Each item is statistically "hashed" to a group within a file based on the content and length of the item-id, or key to the item.
Syntax
Options
Example
Purpose
Related hashing
value
sub-value
item-id
attribute
access.list-item