This option determines how long a document must remain unchanged before it is included in the index and is known as document latency. The rationale for this option is that if a document has changed recently it is likely to be changed again fairly soon, especially if the creator is still editing it and making periodic saves.
You can specify the document latency with the Days, Hours, and Minutes scroll boxes. The latency may be from 0 minutes, which would index all documents regardless, up to 21 days.
Option to automatically keep multi-generational backups of indexes. Backups are always placed in a sub-folder of the current index location called ISYSIndexBackups with individual folders for each version.
The index is backed up every time the index is modified, this can result in multiple backups for a single index update run.
Sometimes the slowest part of an index update can be removing references to changed or deleted documents. Perceptive Search lets you defer this work until later, and only 'marks' those documents as no longer existing, or no longer existing in their old form. The benefit is that your index updates may go much faster where changed or deleted documents are involved. The deferred documents remain in the index taking up space, but will never be found by your queries.
Documents marked for deferred deindexing are automatically physically purged when the amount of space used by them reaches about 20% of your total index size, so you never have to worry about the deferred deindexing consuming large amounts of space (the actual proportion is determined by many factors including the number of words and documents in the index).
Additionally, you may manually purge deferred deleted items at any time using the Purge Deleted option on the Index > Advanced menu. Alternatively this can be scheduled using the Perceptive Search Scheduler wizard. Performing a full Reindex also purges deferred deletions.
Generally, the default setting will be correct but it may be advisable to increase the space allocation to allow for purging to be controlled via a scheduled task.
When Perceptive Search builds an index, it leaves the documents exactly where they are, and just constructs an index that references the original documents. The index is used to rapidly know where specific words occur, and when you click on a document to browse it, the original document is accessed. This results in very small and efficient indexes.
However, sometimes the original documents might be quite slow to access, for example, if they are large PDF documents, or members of ZIP files, or are located across a network or the Internet. Usually, this will not be a problem. However, if you find you are making extensive use of "context" displays (which shows a small extract of each found document in the result list), document access performance might become an issue.
In these situations, select this option and reindex. Perceptive Search will create an additional index file (ISYS.IXG) which will contain a compressed extract of the text of your documents, and document browsing and context displays will perform much more rapidly.
The document cache does not hold a full copy of the document, just the words from the document, and is usually much smaller than the original document.