Re: [sqlite] PRAGMA auto_vacuum

[Pavel Ivanov]

I'd recommend NONE (or 0).

If you have fairly balanced insertions and deletions then there will
be no excessive disk space consumption, vacuuming won't help much. But
with auto-vacuuming turned on you won't have the same performance
because additional code will be executed after each transaction.


Pavel

On Tue, May 11, 2010 at 2:50 PM, Joanne Pham  wrote:
> Hi All,
> I have the database which has a lot of insertion and deletion. Do you have 
> any recomendation about what value that need to be set for auto_vacuum
> in this case to improve the performance for deletion as well as insertion the 
> new row to the database. (0 | NONE | 1 | FULL | 2 | INCREMENTAL;)
> Thanks,
> JP
>
>
>
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[sqlite] PRAGMA auto_vacuum

[Joanne Pham]

Hi All,
I have the database which has a lot of insertion and deletion. Do you have any 
recomendation about what value that need to be set for auto_vacuum
in this case to improve the performance for deletion as well as insertion the 
new row to the database. (0 | NONE | 1 | FULL | 2 | INCREMENTAL;)
Thanks,
JP


  
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Re: [sqlite] PRAGMA auto_vacuum

[Dennis Cote]

Raviv Shasha wrote:
> 
> Can I run the PRAGMA command without using sqlite3_exec command?
> 

Well, yes you could use the prepared statement APIs, but generally 
sqlite3_exec() is somewhat easier for statemnts you don't need to repeat 
(like and insert).

> According to the sqlite documentation the PRAGMA vacuum commands are the
> following :
> 
> For query -> PRAGMA auto_vacuum;
> For Set -> PRAGMA auto_vacuum = 0 | none | 1 | full | 2 | incremental;
> 
> While querying PRAGMA vacuum command, where the retrieved result is
> stored? 
> Do I need to define a variable or special structure for this?
> 

The query form of the pragma commands behave like SQL select statements. 
This query is conceptually equivalent to:

select auto_vacuum from pragmas;

Your syntax is correct. Just make sure you do it before you create any 
tables in the database, as noted in the documentation.

> Therefore, auto-vacuuming must be turned on
> before any tables are created. It is not possible to enable or
> disable auto-vacuum after a table has been created.

HTH
Dennis Cote
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Re: [sqlite] PRAGMA auto_vacuum

[Raviv Shasha]

Hi, 

Thanks for your question. 

Can I run the PRAGMA command without using sqlite3_exec command?

According to the sqlite documentation the PRAGMA vacuum commands are the
following :

For query -> PRAGMA auto_vacuum;
For Set -> PRAGMA auto_vacuum = 0 | none | 1 | full | 2 | incremental;

While querying PRAGMA vacuum command, where the retrieved result is
stored? 
Do I need to define a variable or special structure for this?

I'll appreciate if you can specify the correct PRAGMA syntax.

Thanks in advance,

-Raviv.



-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Dennis Cote
Sent: Monday, March 03, 2008 6:48 PM
To: General Discussion of SQLite Database
Subject: Re: [sqlite] PRAGMA auto_vacuum

Raviv Shasha wrote:
> 
> Sqlite_exec (pDB, "PRAGMA auto_vacuum = 1", NULL, 0, );
> 

Raviv,

That is correct, but you should not the following detail from 
http://www.sqlite.org/pragma.html

> Therefore, auto-vacuuming must be turned on
> before any tables are created. It is not possible to enable or
> disable auto-vacuum after a table has been created.

HTH
Dennis Cote
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Re: [sqlite] PRAGMA auto_vacuum

[Dennis Cote]

Raviv Shasha wrote:
> 
> Sqlite_exec (pDB, "PRAGMA auto_vacuum = 1", NULL, 0, );
> 

Raviv,

That is correct, but you should not the following detail from 
http://www.sqlite.org/pragma.html

> Therefore, auto-vacuuming must be turned on
> before any tables are created. It is not possible to enable or
> disable auto-vacuum after a table has been created.

HTH
Dennis Cote
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[sqlite] PRAGMA auto_vacuum

[Raviv Shasha]

Hi all, 

 

I'll appreciate if anyone can send me the correct syntax for executing
PRAGMA auto_vacuum = 1 command.

 

In the sqlite documentation there is only a list of all available PRAGMA
commands, but I didn't find any code examples.

 

Do I need to execute the PRAGMA auto_vacuum via sqlite_exec as shown as
follows:

 

Sqlite_exec (pDB, "PRAGMA auto_vacuum = 1", NULL, 0, );

 

Thanks a lot,

 

-Raviv.

 

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