Compaction

Short definition

The tightening of a set that has become too bulky to be usefully reloaded: you condense, deduplicate, prioritize, and take out of the default load whatever no longer serves.

Full definition

The word comes from technical systems, where it designates the reorganization of storage to recover space occupied by stale or fragmented data. The operation there is internal and lossless.

In the articles on this blog, the term covers two operations of the same form and opposite statuses, and it is their distinction that gives the entry its interest.

The first is commanded: when the current state swells, when the action list becomes illegible or when you start going in circles, you tighten the workspace and archive what no longer serves, deleting nothing and breaking no traceability. The result is written to disk, rereadable, reversible.

The second is suffered: when a conversation exceeds what the model can hold, the model summarizes the older exchanges of its own accord to make room. It carries the same name because it makes the same gesture, but it is neither announced, nor written, nor reversible — and what it carries away is what hadn't yet been deposited in a file. The first is in fact the countermeasure to the second: you compact deliberately so the model has nothing important left to compact on its own.

Usage in the field

Used to designate the gesture of maintaining a workspace during a session, and to explain why a long conversation loses material with no signal saying so.

Synonyms and variants

"push" for the commanded version, after the name of the command that triggers it; "tighten" when the emphasis falls on volume; "auto-summary" for the suffered version, when you want to lift the ambiguity.

Not to be confused with

• Distillation — picking up a kept source again and turning it into a reformulated and connected idea. It produces new knowledge; compaction only reduces an existing volume.
• Context window — the amount of text a model can process at once. That is the limit whose saturation triggers suffered compaction, not the operation itself.
• Checkpoint — a dated image of a context's complete state, kept to be reread. It freezes in order to keep; compaction tightens in order to carry on.
• deletion — the definitive erasure of a piece of information. Commanded compaction takes things out of the default load and archives them; what leaves stays on disk.

Examples

A session of several hours on a content-production mission: the action list has doubled, the current state repeats the same thing three times, and you tighten before the model starts summarizing the beginning of the conversation on its own account.

Ambiguities / debates

The same word serves for an operation you decide on and an operation done to you. Both usages are attested, and the entry doesn't settle which is legitimate: it holds that they designate things of opposite status, and that conflating them suggests an automatic summary is a form of upkeep.