The only way to give the space from empty index pages back to the OS is through manual compression. Algorithms exist to reuse the empty index and base table pages within the same table or index.
�ystein Gr�vlen wrote:
"TW" == The Wogster <[EMAIL PROTECTED]> writes:TW> �ystein Gr�vlen wrote: >> Is this also true for B-tree indexes? I would imagine that if you >> have a index on a monotocally increasing key (e.g., a timestamp) and >> where you regularly delete old records, there may be a lot of empty >> B-tree pages that will never be possible to reuse.>>TW> What happens in most databases. is that the database has a fixed page TW> size, say 8K, when an index page is full, it splits that page into 2 TW> half pages. When an index page is empty it's dropped from the index, TW> and added to the empty page pool. Many will merge almost empty TW> neighbouring pages, but that doesn't matter for this discussion. I know this. The reason I asked was because I have got the impression that in Derby the only way to drop empty index pages is to do compression.
