On Tue, Nov 27, 2012 at 11:16 PM, Keith Chew wrote:
> I have found that after performing 5000 single transaction inserts, the WAL
> size grows to approx 90MB. After a checkpoint, it becomes 0 and the main
> DB's size goes up by less than 2MB. Is my observation correct? Ie
> Thanks for this Simon, but unfortunately this is legacy code, which has to
> be used for a while. I just did an update to check for column change (we
> have a column to tell us the record has changed, so we do not need to check
> every column), and the WAL file size growth has dropped
>
>
>
> Okay, if you're doing this set up updates to do synchronisation then
> you're going about it a very poor way. We've written a lot on this list
> about the problems with synchronisation over the years and you'll find that
> your way isn't going to be efficient.
>
> Instead of keeping a
On 25 Nov 2012, at 9:12pm, Keith Chew wrote:
> Ok, thanks for the all the suggestions, I will find a workaround. The
> reason I am asking is that I am using sqlite to perform data
> synchronisation between a server and client, and after a day, the WAL file
> size can grow
On Sun, Nov 25, 2012 at 4:12 PM, Keith Chew wrote:
> Hi
>
> Ok, thanks for the all the suggestions, I will find a workaround. The
> reason I am asking is that I am using sqlite to perform data
> synchronisation between a server and client, and after a day, the WAL file
>
Hi
Ok, thanks for the all the suggestions, I will find a workaround. The
reason I am asking is that I am using sqlite to perform data
synchronisation between a server and client, and after a day, the WAL file
size can grow to 3GB, quite a bit. I will look at improving the SQL update
to reduce
On 25 Nov 2012, at 4:22pm, Imanuel wrote:
> I'm not saying your statement is inefficient, I'm saying it's wrong
> because it produces unwanted results.
>
> If the fields a,b,c ('12','34','56') should be updated to
> ('1','2345','6') your statement would fail instead
b||'-'||c||'-' != ...
>
> Maybe there are other drawbacks?
>
> //Roger
> -Ursprungligt meddelande- From: Imanuel Sent: Sunday, November
> 25, 2012 5:22 PM To: sqlite-users@sqlite.org Subject: Re: [sqlite] WAL
> and updates
> I'm not saying your statement is inefficient, I'm saying
Then something like
WHERE a||'-'||b||'-'||c||'-' != ...
Maybe there are other drawbacks?
//Roger
-Ursprungligt meddelande-
From: Imanuel
Sent: Sunday, November 25, 2012 5:22 PM
To: sqlite-users@sqlite.org
Subject: Re: [sqlite] WAL and updates
I'm not saying your statement
I'm not saying your statement is inefficient, I'm saying it's wrong
because it produces unwanted results.
If the fields a,b,c ('12','34','56') should be updated to
('1','2345','6') your statement would fail instead of doing the expected
update.
Which means with every false hit it has less data
On 25 Nov 2012, at 4:11pm, Imanuel wrote:
> Hi Keith
>
>> UPDATE user SET a=1,b=2,c=3 WHERE a||b||c!=1||2||3;
>
> It seems to me that this is not reliable.
> Think the the following text values:
> a='12'
> b='34'
> c='56'
>
> If you want to update these values to:
Hi Keith
> UPDATE user SET a=1,b=2,c=3 WHERE a||b||c!=1||2||3;
It seems to me that this is not reliable.
Think the the following text values:
a='12'
b='34'
c='56'
If you want to update these values to:
a='1'
b='2345'
c='6'
Then your statement would not update because '123456' = '123456'.
On 25 Nov 2012, at 10:46am, Keith Chew wrote:
> I found that when an update SQL is issued against a table, the WAL file
> gets updated with the new record, even though the record is exactly the
> same as the current record.
>
> [snip]
>
> Is there a specific reason for
On Mon, 26 Nov 2012 00:16:39 +1300, Keith Chew
wrote:
>Hi Richard
>
>
>>
>> UPDATE user SET user_name='Keith' WHERE user_name!='Keith';
>>
>>
>>
>The example I provided was simplified only to explain the scenario. In a
>production environment, there are over 40-50 columns,
Hi Richard
>
> UPDATE user SET user_name='Keith' WHERE user_name!='Keith';
>
>
>
The example I provided was simplified only to explain the scenario. In a
production environment, there are over 40-50 columns, and the suggested
workaround above is impractical.
Regards
Keith
On Sun, Nov 25, 2012 at 5:46 AM, Keith Chew wrote:
> Hi
>
> I found that when an update SQL is issued against a table, the WAL file
> gets updated with the new record, even though the record is exactly the
> same as the current record.
>
> Eg user table has 1 record with
Hi
I found that when an update SQL is issued against a table, the WAL file
gets updated with the new record, even though the record is exactly the
same as the current record.
Eg user table has 1 record with user_name = 'Keith'. Issuing this SQL will
increase the WAL file:
update user set
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