Using mkvdk for Incremental Squeeze
The incremental squeeze is a collection optimization feature of the mkvdk command-line tool. Using incremental squeeze, the application administrator can save on the disk space required for squeezing a collection.
Incremental squeeze uses significantly less disk space to squeeze a collection than a normal squeeze. If normal squeezing is performed, the disk space required can be up to double the size of a collection. When a squeeze is performed on a collection, all of the collection's partitions that have deleted documents are recreated without the deleted documents so that continuous access to the collection is possible. After the reap interval time, the original partitions (with the deleted documents) are removed. Before the reap interval time, both old and new partitions exist, sometimes occupying almost double the space.
Using incremental squeeze, the Verity engine first brings down the collection, and then squeezes the partitions in the collection one by one. After each partition is squeezed into a new partition, the corresponding old partition is removed immediately before the next partition is squeezed. After squeezing all of the partitions, the engine brings the collection back up. The behavior of incremental squeeze ensures that the extra disk space required to squeeze a collection is equal to the size of the largest partition at most.
To implement incremental squeeze, you run the mkvdk command-line tool with a set of style files, including a style.plc
file that has a special /incremental_squeeze=YES
entry. The mkvdk syntax used to invoke the incremental squeeze feature is:
- mkvdk -collection
coll
-optimize squeeze
where coll_name
represents the collection name.
The style.plc
entry for incremental squeeze is specified as an attribute to the indexing mode used. A sample style.plc
file is below.
- $control: 1
- policy:
- {
- mode: default
- /inherit=generic
- /incremental_squeeze=yes
- }
With the sample style.plc
file, the Verity engine uses the incremental squeeze feature when an mkvdk call is made with -optimize squeeze
. The default indexing mode does not implement incremental squeeze.
Copyright © 2002, Verity, Inc. All rights
reserved.