>From what I read SQL Server has 2 basic types of index:
1. Clustered, that holds the single instance of the data itself (actaully the
whole row)
2. Non-clustered that hold a pointer to the single instance of the data, but not
the data itself.
Clive
John Stanton <[EMAIL PROTECTED]> on 04/10/2007 20:02:16
Please respond to sqlite-users@sqlite.org
To: sqlite-users@sqlite.org
cc: (bcc: clive/Emultek)
Subject: Re: [sqlite] Index size in file
A B-Tree index holds keys in sorted sequence. They are in random
sequence in the database. That requires holding the keys in the B-Tree
nodes.
A hashed type access does not have that storage overhead, but it does
not deliver the rows in sorted sequence.
[EMAIL PROTECTED] wrote:
>
>
> I am not an expert on indexes, however it does seem strange to me that a
> database should keep duplicate data in it.
> This prompted me to look up how indexes are stored in other databases. To tell
> the truth I only looked at one, and that is SQL Server.
> They do not store any duplicate data. If you would like the reference I can
give
> it to you.
> I agree with you that it means an extra lookup that could make things slower,
(
> I say could because you use more space in the cache which could result in more
> reads)
> Anyway given that that is the way it is implemented, does anyone know if it is
> possible to create an index in memory?
>
> Clive
>
>
>
>
>
> John Stanton <[EMAIL PROTECTED]> on 03/10/2007 17:36:58
>
> Please respond to sqlite-users@sqlite.org
>
> To: sqlite-users@sqlite.org
> cc: (bcc: clive/Emultek)
>
> Subject: Re: [sqlite] Index size in file
>
>
>
> An index which does not hold keys is not an index. If you don't want to
> allocate space for indexing then you put up with slow performance and
> use row searches.
>
> [EMAIL PROTECTED] wrote:
>
>>
>>I created an index on a TEXT column as I want to be able to
>>I noticed a large increase in the file size.
>>Looking at the binary of the file, I see that the index has a copy of all the
>>data being indexed.
>>1. Is this necassary?
>>2. Is there a way to keep the index only in memory and not in the file.
>>
>>Clive
>>
>>
>>
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