Re: Deleted records and index size

I have a feeling this is one of those "it depends" answers. I think I know that the index is rebuilt when a record is deleted from the PF - I think 1 record deleted would have little impact on size of the LF, since everything has to to use 4K pages, you can't have smaller units that than.

Now the radix tree doesn't use full values, IIRC - it uses substrings, I think - and the effect of rebuilding this depends on the values deleted, right?

Here is a picture of a radix tree -

http://en.wikipedia.org/wiki/File:An_example_of_how_to_find_a_string_in_a_Patricia_trie.png

It would be interesting to compare sizes after deleting 30% of the records in a 100,000-record file, say.

Vern

On 2/3/2014 1:13 PM, Alan Campin wrote:

Does the amount of disk space that the index occupies decrease. I am trying
to figure how much additional storage that a copy of a physical file and
it's logicals would require assuming that the deleted records are not
copied.


On Mon, Feb 3, 2014 at 12:02 PM, Booth Martin <booth@xxxxxxxxxxxx> wrote:

Not sure of the question. Are you asking if the space is reclaimed?
Does the physical size of the index decrease? Or are asking if the
space on disk for the record's index is wiped clean and remains unused
until the file is moved, reorganized, or some other activity that causes
a rewrite of the data?


On 2/3/2014 12:57 PM, Alan Campin wrote:

Does anybody know. If you delete a record, does the index size decrease?

I am getting indications both way, that it keeps the deleted record in
index and logical indexes and other stuff that seems to say it deletes

the

record from the indexes.

I found IBM's information on calculating index size but it only says

number

of records and nothing about deleted record.

It would seem logical that it would not keep an entry in the index.

Anyway, thanks. .

--
Booth Martin
www.martinvt.com
(802)461-5349
Skype: booth.martin

Never call a man a fool; borrow from him.
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