Re: [sqlite] Re: Changing Schema On The Fly
--- Mitchell Vincent <[EMAIL PROTECTED]> wrote: > I guess this isn't possible after all? Get the SQLite ODBC driver source code and alter it to do whatever you like when the type "timestamp" column comes up. > On 5/31/07, Mitchell Vincent <[EMAIL PROTECTED]> wrote: > > I have a set of databases that contain a date type called "timestamp". > > I need to make those "integer" so they come through the ODBC driver > > the right way. Is there any way to change all of that through queries > > on-the-fly? I'd like to avoid re-creating all the databases if > > possible.. ___ You snooze, you lose. Get messages ASAP with AutoCheck in the all-new Yahoo! Mail Beta. http://advision.webevents.yahoo.com/mailbeta/newmail_html.html - To unsubscribe, send email to [EMAIL PROTECTED] -
[sqlite] Re: Changing Schema On The Fly
I guess this isn't possible after all? On 5/31/07, Mitchell Vincent <[EMAIL PROTECTED]> wrote: I have a set of databases that contain a date type called "timestamp". I need to make those "integer" so they come through the ODBC driver the right way. Is there any way to change all of that through queries on-the-fly? I'd like to avoid re-creating all the databases if possible.. Thanks! -- - Mitchell Vincent - K Software - Innovative Software Solutions - Visit our website and check out our great software! - http://www.ksoftware.net - To unsubscribe, send email to [EMAIL PROTECTED] -
RE: [sqlite] Age calculation on literal
Got the syntax right, but not the logic.
I believe this (VB) function will now get the right SQL to get the age in
months:
Function ISO8601Date2AgeInMonths(strField As String, _
Optional strAlias As String) As String
Dim strAS As String
If Len(strAlias) > 0 Then
strAS = " AS "
End If
ISO8601Date2AgeInMonths = "case when date('now') >= " & _
"date(" & strField & ", '+' || (strftime('%Y',
'now') - " & _
"strftime('%Y', " & strField & ")) || ' years')
then " & _
"case when strftime('%d', 'now') <
strftime('%d', " & strField & ") then " & _
"((strftime('%Y', 'now') - strftime('%Y', " &
strField & ")) * 12 + " & _
"(strftime('%m', 'now') - strftime('%m', " &
strField & "))) - 1 " & _
"else " & _
"((strftime('%Y', 'now') - strftime('%Y', " &
strField & ")) * 12 + " & _
"(strftime('%m', 'now') - strftime('%m', " &
strField & "))) - 0 " & _
"end " & _
"else " & _
"case when " & _
"strftime('%d', 'now') < strftime('%d', " &
strField & ") " & _
"then " & _
"(strftime('%Y', 'now') - strftime('%Y', " &
strField & ") - 1) * 12 + " & _
"(strftime('%m', 'now') + (12 - strftime('%m', "
& strField & "))) - 1 " & _
"else " & _
"((strftime('%Y', 'now') - strftime('%Y', " &
strField & ") - 1) * 12 + " & _
"(strftime('%m', 'now') + (12 - strftime('%m', "
& strField & " - 0 " & _
"End " & _
"End" & strAS & strAlias
End Function
RBS
-Original Message-
From: RB Smissaert [mailto:[EMAIL PROTECTED]
Sent: 01 June 2007 21:46
To: sqlite-users@sqlite.org
Subject: RE: [sqlite] Age calculation on literal
Got this now, after correcting the brackets:
SELECT
case when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y', '2006-
10-14')) || ' years') <= date('now') then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
end
else
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14'))) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') + (12 - strftime('%m', '2006-10-14')))
end
end
RBS
-Original Message-
From: Dennis Cote [mailto:[EMAIL PROTECTED]
Sent: 01 June 2007 19:53
To: sqlite-users@sqlite.org
Subject: Re: [sqlite] Age calculation on literal
On 6/1/07, RB Smissaert <[EMAIL PROTECTED]> wrote:
>
> Got this nearly worked out now, but somehow I can't get the nested case
> when
> syntax right:
>
> SELECT
> case
> when
> date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
> '2006-10-14')) || ' years') <= date('now')
> then
> case when
> strftime('%d', 'now') > strftime('%d', '2006-10-14')
> then
> ((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
> (strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
> else
> (strftime('%Y', 'now') - strftime('%Y', '2006-10-14'))) * 12 +
You have an extra closing bracket in the line above.
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
> end
> else
> case when
> strftime('%d', 'now') > strftime('%d', '2006-10-14')
> then
> ((strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
> (strftime('%m', 'now') +
> (12 - strftime('%m', '2006-10-14' -1
> else
> (strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
> (strftime('%m', 'now') +
> (12 - strftime('%m', '2006-10-14')))
> end
> end
>
> It will give me an error (from my VB wrapper) syntax error near else.
> Any idea what is wrong here?
Try this instead, I find the extra indentation makes it easier to see what
you are doing.
SELECT
case when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
'2006-10-14')) || ' years') <= date('now')
then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
RE: [sqlite] Age calculation on literal
Got this now, after correcting the brackets:
SELECT
case when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y', '2006-
10-14')) || ' years') <= date('now') then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
end
else
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14'))) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') + (12 - strftime('%m', '2006-10-14')))
end
end
RBS
-Original Message-
From: Dennis Cote [mailto:[EMAIL PROTECTED]
Sent: 01 June 2007 19:53
To: sqlite-users@sqlite.org
Subject: Re: [sqlite] Age calculation on literal
On 6/1/07, RB Smissaert <[EMAIL PROTECTED]> wrote:
>
> Got this nearly worked out now, but somehow I can't get the nested case
> when
> syntax right:
>
> SELECT
> case
> when
> date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
> '2006-10-14')) || ' years') <= date('now')
> then
> case when
> strftime('%d', 'now') > strftime('%d', '2006-10-14')
> then
> ((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
> (strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
> else
> (strftime('%Y', 'now') - strftime('%Y', '2006-10-14'))) * 12 +
You have an extra closing bracket in the line above.
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
> end
> else
> case when
> strftime('%d', 'now') > strftime('%d', '2006-10-14')
> then
> ((strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
> (strftime('%m', 'now') +
> (12 - strftime('%m', '2006-10-14' -1
> else
> (strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
> (strftime('%m', 'now') +
> (12 - strftime('%m', '2006-10-14')))
> end
> end
>
> It will give me an error (from my VB wrapper) syntax error near else.
> Any idea what is wrong here?
Try this instead, I find the extra indentation makes it easier to see what
you are doing.
SELECT
case when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
'2006-10-14')) || ' years') <= date('now')
then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
end
else
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14' -1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') + (12 - strftime('%m', '2006-10-14')))
end
end
HTH
Dennis Cote
-
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RE: [sqlite] Age calculation on literal
Yes, that looks better and thanks for that.
Still get the same error though.
I will keep fiddling with it.
RBS
-Original Message-
From: Dennis Cote [mailto:[EMAIL PROTECTED]
Sent: 01 June 2007 19:53
To: sqlite-users@sqlite.org
Subject: Re: [sqlite] Age calculation on literal
On 6/1/07, RB Smissaert <[EMAIL PROTECTED]> wrote:
>
> Got this nearly worked out now, but somehow I can't get the nested case
> when
> syntax right:
>
> SELECT
> case
> when
> date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
> '2006-10-14')) || ' years') <= date('now')
> then
> case when
> strftime('%d', 'now') > strftime('%d', '2006-10-14')
> then
> ((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
> (strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
> else
> (strftime('%Y', 'now') - strftime('%Y', '2006-10-14'))) * 12 +
You have an extra closing bracket in the line above.
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
> end
> else
> case when
> strftime('%d', 'now') > strftime('%d', '2006-10-14')
> then
> ((strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
> (strftime('%m', 'now') +
> (12 - strftime('%m', '2006-10-14' -1
> else
> (strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
> (strftime('%m', 'now') +
> (12 - strftime('%m', '2006-10-14')))
> end
> end
>
> It will give me an error (from my VB wrapper) syntax error near else.
> Any idea what is wrong here?
Try this instead, I find the extra indentation makes it easier to see what
you are doing.
SELECT
case when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
'2006-10-14')) || ' years') <= date('now')
then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
end
else
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14' -1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') + (12 - strftime('%m', '2006-10-14')))
end
end
HTH
Dennis Cote
-
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-
Re: [sqlite] Concurrency
At 20:58 01/06/2007, you wrote: >On 6/1/07, Eduardo Morras <[EMAIL PROTECTED]> wrote: > >>If i remember well, sqlite uses two databases for metadata/schema > >Databases or tables? Could you be thinking of the sqlite_master table? You're right 1 db and 2 tables. Yes i'm thinking on sqlite_master table. Thanks Usuario de FreeBSD+Xfce, OpenOffice y muchos mas OSS. Microsoft declara que el OSS viola 235 patentes. Por favor, DENUNCIAME. - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Does Attach improve Concurrency ?
At 19:32 01/06/2007, you wrote: >When you have a connection with multiple attached databases and the >connection acquires an exclusive lock, does it always lock all attached >databases or does it keep track of which databases require the lock? Does >using separate databases and attaching them improve concurrency (by >providing finer-grained locking)? It locks all attached databases. No, it does not improve concurrency but i can improve speed if database files are on more than one phisical disk. The sqlite bottleneck is i/o access on most cases. Usuario de FreeBSD+Xfce, OpenOffice y muchos mas OSS. Microsoft declara que el OSS viola 235 patentes. Por favor, DENUNCIAME. - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
On 6/1/07, Eduardo Morras <[EMAIL PROTECTED]> wrote: If i remember well, sqlite uses two databases for metadata/schema Databases or tables? Could you be thinking of the sqlite_master table? - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Age calculation on literal
On 6/1/07, RB Smissaert <[EMAIL PROTECTED]> wrote:
Got this nearly worked out now, but somehow I can't get the nested case
when
syntax right:
SELECT
case
when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
'2006-10-14')) || ' years') <= date('now')
then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14'))) * 12 +
You have an extra closing bracket in the line above.
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
end
else
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14' -1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14')))
end
end
It will give me an error (from my VB wrapper) syntax error near else.
Any idea what is wrong here?
Try this instead, I find the extra indentation makes it easier to see what
you are doing.
SELECT
case when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
'2006-10-14')) || ' years') <= date('now')
then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
end
else
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14' -1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') - 1) * 12 +
(strftime('%m', 'now') + (12 - strftime('%m', '2006-10-14')))
end
end
HTH
Dennis Cote
Re: [sqlite] Concurrency
At 19:24 01/06/2007, you wrote: >Why you said less than 29? SQLite has a soft limit of 10 databases and a hard limit of 32, you can change it at compile time. If i remember well, sqlite uses two databases for metadata/schema, so you get a max of 30 databases, you need another one as master db, so you get 29 free databases. --- Nunca mezclo pastillas con alcohol, ... las disuelvo. - To unsubscribe, send email to [EMAIL PROTECTED] -
[sqlite] Does Attach improve Concurrency ?
When you have a connection with multiple attached databases and the connection acquires an exclusive lock, does it always lock all attached databases or does it keep track of which databases require the lock? Does using separate databases and attaching them improve concurrency (by providing finer-grained locking)? Thanks, Sam - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
Why you said less than 29? --- Marco Bambini http://www.sqlabs.net http://www.sqlabs.net/blog/ http://www.sqlabs.net/realsqlserver/ On Jun 1, 2007, at 6:56 PM, Eduardo Morras wrote: At 11:17 01/06/2007, you wrote: Hi, I am having a scenario where I have one reader/writer and many writer threads. All writers are pretty basic (single INSERT INTO; some sort of a logging info what a thread has done). I believe I will receive many BUSY return codes and I don't like these spinlock-like retries. The problem I am having with this design is that I would like to complete the thread ASAP, so that I don't have many threads idling and consuming resources of my embedded system. I was thinking to either: a. Use mutex/semaphore before writting to the database or b. Have a (thread safe) list of INSERT INTO strings that every writer thread populates and the main reader/writer thread later executes. Is this a good approach? Does anyone have a better design? I don't want to use other database, because I think Sqlite is great for an embedded system that I am using. How many threads have you?. If threads number is low (less than 29) you can use a database for each thread. Each one will have it's own file and no write lock problems. From time to time a simple sql query can get all data from those databases, write to the main one and delete the databases. HTH - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
At 11:17 01/06/2007, you wrote: >Hi, > >I am having a scenario where I have one reader/writer and many writer threads. >All writers are pretty basic (single INSERT INTO; some sort of a logging info >what a thread has done). > >I believe I will receive many BUSY return codes and I don't like these >spinlock-like retries. The problem I am having with this design is that I would >like to complete the thread ASAP, so that I don't have many threads idling and >consuming resources of my embedded system. > >I was thinking to either: > >a. Use mutex/semaphore before writting to the database or > >b. Have a (thread safe) list of INSERT INTO strings that every writer thread >populates and the main reader/writer thread later executes. > >Is this a good approach? Does anyone have a better design? I don't want to use >other database, because I think Sqlite is great for an embedded system that I >am using. How many threads have you?. If threads number is low (less than 29) you can use a database for each thread. Each one will have it's own file and no write lock problems. From time to time a simple sql query can get all data from those databases, write to the main one and delete the databases. HTH Usuario de FreeBSD+Xfce, OpenOffice y muchos mas OSS. Microsoft declara que el OSS viola 235 patentes. Por favor, DENUNCIAME. - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Re: CAST
> Sqlite lets us advance our storage > capabilities into a more flexible world. Sure, but it's not allways a good thing. Usually one column stores related data. Related data mostly have the same type. Entering a value of different type is an error which is silently ignored. Allowing different types gives us more flexibility, but is also more error-prone. Ofcourse there are other databases that can be chosen instead of SQLite if type safety is required, but compile time option wouldn't hurt SQLite in any way. --- CTR brzmi tajemniczo ? Sprawd¼ co mo¿esz zyskaæ na >>> http://link.interia.pl/f1a9d - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
On Friday, June 01, 2007 Ian Frosst wrote: > For Windows, this is not the case with Automatic Reset events. The system > guarantees that only one thread waiting on the event is woken up (it keeps a > queue): the others happily keep sleeping until the next setting of the > event. That may work for you, but has the possible drawback of starving a thread... Windows doesn't guarantee that the woken thread is the one at the head of the "queue." See, e.g., http://blogs.msdn.com/oldnewthing/archive/2006/03/13/550402.aspx So, I never use PulseEvent or Automatic Reset events. Of course, if you expect there to be intervals when there are no waiting threads, and you can afford to wait for that interval for a synchronization point, and you don't care the order in which the inserts are performed, the Automatic Reset event might work. e > On 6/1/07, Doug Currie <[EMAIL PROTECTED]> wrote: >> >> On Friday, June 01, 2007 Ian Frosst wrote: >> >> > On the topic of a more efficient busy handler, one approach I considered >> > was to implement an event which was signalled when a database unlock >> > occurred. >> > That way, the busy handler could just wait on the event (which is an >> > efficient wait state), and be guaranteed of a wake up when the lock is >> > released (the event would be signalled at this time.) However, I wasn't >> > at the time familiar enough with SQLite's innards to implement such a >> > beast. >> > Can anyone see any pitfalls to such an approach? >> >> The problems occur when multiple threads are waiting on the event; >> they all wake up and compete for the resource again. For better >> solutions, see: http://world.std.com/~jmhart/batons.htm -- Doug Currie Londonderry, NH, USA - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
[EMAIL PROTECTED] wrote: Hi, I am having a scenario where I have one reader/writer and many writer threads. All writers are pretty basic (single INSERT INTO; some sort of a logging info what a thread has done). I believe I will receive many BUSY return codes and I don't like these spinlock-like retries. The problem I am having with this design is that I would like to complete the thread ASAP, so that I don't have many threads idling and consuming resources of my embedded system. I was thinking to either: a. Use mutex/semaphore before writting to the database or b. Have a (thread safe) list of INSERT INTO strings that every writer thread populates and the main reader/writer thread later executes. Is this a good approach? Does anyone have a better design? I don't want to use other database, because I think Sqlite is great for an embedded system that I am using. ___ Najhitrej¹i brezplaèni klicni dostop :: Varno in zanesljivo po internetu Obi¹èite http://www.dialup386.com/ - To unsubscribe, send email to [EMAIL PROTECTED] - When you have multiple writes using sqlite you will need to perform a syncrhonization of some form. I would recommend using option "b" that you indicated. Create a thread that connects to the DB and handles all of you i/o to sqlite. That way you will never get a db locked or busy retry... Take a look at src/test_server.c for an example implementation. For your case you really don't need to implement the "shared cache". Just create a simple db open internally to the thread. Have each client send its insert data into the "servers" incoming work queue. This will work as long as the "clients" don't need to wait or guarantee durability before proceeding.
RE: [sqlite] Concurrency
Nice analogy, but in the case the cat really does have 9 lives (or many more) 'cause with SQLITE_BUSY you can just retry and while retrying is a performance penalty in my experience SQLITE_BUSY is a very rare occurrence. All I'm saying is don't fix a perceived problem until you've tested to be sure your perception is correct. Sam --- We're Hiring! Seeking a passionate developer to join our team building Flex based products. Position is in the Washington D.C. metro area. If interested contact [EMAIL PROTECTED] -Original Message- From: John Stanton [mailto:[EMAIL PROTECTED] Sent: Friday, June 01, 2007 9:40 AM To: sqlite-users@sqlite.org Subject: Re: [sqlite] Concurrency You make a very good point. Someone called it the "cat running over the road" situation. A cat runs across a busy road without looking by going as fast as possible and rarely does one get run over. On the other hand roads are lined with dead armadillos. If you synchronization logic is sound and you avoid polling or waits the faster your database runs the more concurrent transactions per second you will achieve. - To unsubscribe, send email to [EMAIL PROTECTED] - - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
For Windows, this is not the case with Automatic Reset events. The system guarantees that only one thread waiting on the event is woken up (it keeps a queue): the others happily keep sleeping until the next setting of the event. On 6/1/07, Doug Currie <[EMAIL PROTECTED]> wrote: On Friday, June 01, 2007 Ian Frosst wrote: > On the topic of a more efficient busy handler, one approach I considered was > to implement an event which was signalled when a database unlock occurred. > That way, the busy handler could just wait on the event (which is an > efficient wait state), and be guaranteed of a wake up when the lock is > released (the event would be signalled at this time.) However, I wasn't at > the time familiar enough with SQLite's innards to implement such a beast. > Can anyone see any pitfalls to such an approach? The problems occur when multiple threads are waiting on the event; they all wake up and compete for the resource again. For better solutions, see: http://world.std.com/~jmhart/batons.htm e -- Doug Currie Londonderry, NH, USA - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
On Friday, June 01, 2007 Ian Frosst wrote: > On the topic of a more efficient busy handler, one approach I considered was > to implement an event which was signalled when a database unlock occurred. > That way, the busy handler could just wait on the event (which is an > efficient wait state), and be guaranteed of a wake up when the lock is > released (the event would be signalled at this time.) However, I wasn't at > the time familiar enough with SQLite's innards to implement such a beast. > Can anyone see any pitfalls to such an approach? The problems occur when multiple threads are waiting on the event; they all wake up and compete for the resource again. For better solutions, see: http://world.std.com/~jmhart/batons.htm e -- Doug Currie Londonderry, NH, USA - To unsubscribe, send email to [EMAIL PROTECTED] -
[sqlite] Sqlite 3 Crash on OSX
Folks. My app just crashed in the field randomly after some time running fine. Thread 12 Crashed: 0 libsqlite3.0.dylib 0x9406e587 sqlite3pager_get + 390 1 libsqlite3.0.dylib 0x94054275 sqlite3BtreeCopyFile + 381 2 libsqlite3.0.dylib 0x940542dd sqlite3BtreeCopyFile + 485 3 libsqlite3.0.dylib 0x940545b6 sqlite3BtreeLast + 134 4 libsqlite3.0.dylib 0x940830c1 sqlite3VdbeExec + 16021 5 libsqlite3.0.dylib 0x94084c73 sqlite3_step + 270 6 libsqlite3.0.dylib 0x9408b343 sqlite3_exec + 260 7 libsqlite3.0.dylib 0x9407a53d sqlite3_get_table + 189 Anyone have anything specific to suggest ? Cheers Mark. -- [EMAIL PROTECTED] Tel: +44 208 340 5677 fax: +44 870 055 7790 http://www.gallery.co.uk - To unsubscribe, send email to [EMAIL PROTECTED] -
RE: [sqlite] Age calculation on literal
Got this nearly worked out now, but somehow I can't get the nested case when
syntax right:
SELECT
case
when
date('2006-10-14', '+' || (strftime('%Y', 'now') - strftime('%Y',
'2006-10-14')) || ' years') <= date('now')
then
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14')) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14')) - 1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14'))) * 12 +
(strftime('%m', 'now') - strftime('%m', '2006-10-14'))
end
else
case when
strftime('%d', 'now') > strftime('%d', '2006-10-14')
then
((strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14' -1
else
(strftime('%Y', 'now') - strftime('%Y', '2006-10-14') -1) * 12 +
(strftime('%m', 'now') +
(12 - strftime('%m', '2006-10-14')))
end
end
It will give me an error (from my VB wrapper) syntax error near else.
Any idea what is wrong here?
RBS
-Original Message-
From: Dennis Cote [mailto:[EMAIL PROTECTED]
Sent: 31 May 2007 22:17
To: sqlite-users@sqlite.org
Subject: Re: [sqlite] Age calculation on literal
RB Smissaert wrote:
> Thanks to Dennis Cote I got a nice way to get the age from the date in the
> form '-nmm-dd'. It works fine when I run it on a field, but when I run
> it on a literal date it gives me 100 too much:
>
> select
> case when
> date('2002-01-01', '+' || (strftime('%Y', 'now') -
> strftime('%Y', '2002-01-01')) || ' years') <= date('now')
> then
> strftime('%Y', 'now') - strftime('%Y', '2002-01-01')
> else
> strftime('%Y', 'now') - strftime('%Y', '2002-01-01') - 1
> end
>
> Why is this?
>
>
This works for me in the sqlite shell as shown below:
C:\Documents and Settings\DennisC>sqlite3
SQLite version 3.3.15
Enter ".help" for instructions
sqlite>
sqlite> select
...> case when
...> date('2002-01-01', '+' || (strftime('%Y', 'now') -
...> strftime('%Y', '2002-01-01')) || ' years') <= date('now')
...> then
...> strftime('%Y', 'now') - strftime('%Y', '2002-01-01')
...> else
...> strftime('%Y', 'now') - strftime('%Y', '2002-01-01') - 1
...> end
...> ;
5
How are you running this query?
Dennis Cote
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Re: [sqlite] Concurrency
With other applications you can use semaphores for synchronization and achieve minimal latency and a low overhead. If you have networked files you are dependent upon the file locking and on the effectiveness of the cross network file locking. This does not necessarily work as expected and in particular notorious cases does not work at all. If you want maximal performance across a nwetwork you need to implement a server to manage the database on one machine. Israel Figueroa wrote: What if the database is locked by another application, or by another box? The driver should poll untill it get an "idle database" and then thow an event... and then, we're polling again. I'm coding some similar to the original post... I'm not that good with threads yet, but I did foresee that even with my tiny inserts maybe some moment I could get a Sqlite_busy. Is that bad just keep inserting until i get a Sqlite_ok ? Assuming that is not a multiuser enviroment, just one app accesing the database. 2007/6/1, Ian Frosst <[EMAIL PROTECTED]>: On the topic of a more efficient busy handler, one approach I considered was to implement an event which was signalled when a database unlock occurred. That way, the busy handler could just wait on the event (which is an efficient wait state), and be guaranteed of a wake up when the lock is released (the event would be signalled at this time.) However, I wasn't at the time familiar enough with SQLite's innards to implement such a beast. Can anyone see any pitfalls to such an approach? Ian On 6/1/07, John Stanton <[EMAIL PROTECTED]> wrote: > > Tom Briggs wrote: > > > > > >>I don't want to use > >>other database, because I think Sqlite is great for an > >>embedded system that I > >>am using. > > > > > >I think that your own questions about concurrency prove this > > incorrect. If you need high concurrency and you don't like retries, > > SQLite is not the database for you. > > > >-T > > > > If you require ACID type data integrity and have a single disk there is > no such thing as a "high concurrency database". They all share a single > disk resource in some way. With Sqlite it is up to the designer to > build in concurrency and that cna be done by single streaming. Better > performance is achieved by using a single database connection so that > cache hits are maximized. > > If your design is such that you never get a busy then you have an > effective allocation of your disk resource. Using mutexes between > threads and semaphores between processes gives you that capability. > > To my mind the only time you should use the busy logic is when you are > working across a network with shared files. > > > > - > To unsubscribe, send email to [EMAIL PROTECTED] > > - > > - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
What if the database is locked by another application, or by another box? The driver should poll untill it get an "idle database" and then thow an event... and then, we're polling again. I'm coding some similar to the original post... I'm not that good with threads yet, but I did foresee that even with my tiny inserts maybe some moment I could get a Sqlite_busy. Is that bad just keep inserting until i get a Sqlite_ok ? Assuming that is not a multiuser enviroment, just one app accesing the database. 2007/6/1, Ian Frosst <[EMAIL PROTECTED]>: On the topic of a more efficient busy handler, one approach I considered was to implement an event which was signalled when a database unlock occurred. That way, the busy handler could just wait on the event (which is an efficient wait state), and be guaranteed of a wake up when the lock is released (the event would be signalled at this time.) However, I wasn't at the time familiar enough with SQLite's innards to implement such a beast. Can anyone see any pitfalls to such an approach? Ian On 6/1/07, John Stanton <[EMAIL PROTECTED]> wrote: > > Tom Briggs wrote: > > > > > >>I don't want to use > >>other database, because I think Sqlite is great for an > >>embedded system that I > >>am using. > > > > > >I think that your own questions about concurrency prove this > > incorrect. If you need high concurrency and you don't like retries, > > SQLite is not the database for you. > > > >-T > > > > If you require ACID type data integrity and have a single disk there is > no such thing as a "high concurrency database". They all share a single > disk resource in some way. With Sqlite it is up to the designer to > build in concurrency and that cna be done by single streaming. Better > performance is achieved by using a single database connection so that > cache hits are maximized. > > If your design is such that you never get a busy then you have an > effective allocation of your disk resource. Using mutexes between > threads and semaphores between processes gives you that capability. > > To my mind the only time you should use the busy logic is when you are > working across a network with shared files. > > > > - > To unsubscribe, send email to [EMAIL PROTECTED] > > - > > -- Thanks God
RE: [sqlite] Concurrency
// wrapper for sqlite3_prepare_v2 which retries
creating statements if the db returns SQLITE_BUSY or
SQLITE_LOCKED
int sql_prepare(sqlite3 *db, const char *sql,
sqlite3_stmt **ppStmt, int wait) {
#ifdef SQL_DEBUG
printf(sql);
printf("\n");
fflush(stdout);
#endif
int rc;
char looper[4] = {'|','/','-','\\'};
int looperc = 0;
int waited = 0;
while (1) {
rc = sqlite3_prepare_v2(db,sql,-1,ppStmt,NULL);
if (rc == SQLITE_LOCKED || rc == SQLITE_BUSY) {
if (wait != 0) {
fprintf(stdout,"Database is locked or busy.
Waiting %is ... %1c\r", ++waited,
looper[looperc]);
fflush(stdout);
wait--;
looperc = ++looperc % sizeof(looper);
sleep(1);
} else {
fprintf(stderr,"Database was locked or busy
while
creating statement. I've given up.\n");
return rc;
}
} else {
if (waited != 0) printf("\n\n");
return rc;
}
}
}
--- [EMAIL PROTECTED] schrieb:
> Hi,
>
> I am having a scenario where I have one
> reader/writer and many writer threads.
> All writers are pretty basic (single INSERT INTO;
> some sort of a logging info
> what a thread has done).
>
> I believe I will receive many BUSY return codes and
> I don't like these
> spinlock-like retries. The problem I am having with
> this design is that I would
> like to complete the thread ASAP, so that I don't
> have many threads idling and
> consuming resources of my embedded system.
>
> I was thinking to either:
>
> a. Use mutex/semaphore before writting to the
> database or
>
> b. Have a (thread safe) list of INSERT INTO strings
> that every writer thread
> populates and the main reader/writer thread later
> executes.
>
> Is this a good approach? Does anyone have a better
> design? I don't want to use
> other database, because I think Sqlite is great for
> an embedded system that I
> am using.
>
___
> Najhitrej¹i brezplaèni klicni dostop :: Varno in
> zanesljivo po internetu
> Obi¹èite http://www.dialup386.com/
>
>
-
> To unsubscribe, send email to
> [EMAIL PROTECTED]
>
-
>
>
___
Telefonate ohne weitere Kosten vom PC zum PC: http://messenger.yahoo.de
-
To unsubscribe, send email to [EMAIL PROTECTED]
-
Re: [sqlite] Concurrency
Samuel R. Neff wrote: If option (b), using a single thread for writing and a multi-threaded write queue works in your situation, then that would probably provide best concurrency and performance. The only downside to this is the delayed writes mean you don't as easily get feedback to the original writer if a write fails (bad data for example). You could build delayed feedback/callback into the system, just depends on your application architecture. Also, I would strongly suggest doing some actual testing and confirming there is a bottleneck without any custom code to increase concurrency before programming workarounds for an expected problem. What we've found is that SQLite is so much faster than other databases (MSSQL in particular) that concurrency is greatly improved simply because each write is faster and thus the time the db is locked is less even though the whole db is locked. HTH, Sam --- We're Hiring! Seeking a passionate developer to join our team building products. Position is in the Washington D.C. metro area. If interested contact [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Friday, June 01, 2007 5:18 AM To: sqlite-users@sqlite.org Subject: [sqlite] Concurrency Hi, I am having a scenario where I have one reader/writer and many writer threads. All writers are pretty basic (single INSERT INTO; some sort of a logging info what a thread has done). I believe I will receive many BUSY return codes and I don't like these spinlock-like retries. The problem I am having with this design is that I would like to complete the thread ASAP, so that I don't have many threads idling and consuming resources of my embedded system. I was thinking to either: a. Use mutex/semaphore before writting to the database or b. Have a (thread safe) list of INSERT INTO strings that every writer thread populates and the main reader/writer thread later executes. Is this a good approach? Does anyone have a better design? I don't want to use other database, because I think Sqlite is great for an embedded system that I am using. You make a very good point. Someone called it the "cat running over the road" situation. A cat runs across a busy road without looking by going as fast as possible and rarely does one get run over. On the other hand roads are lined with dead armadillos. If you synchronization logic is sound and you avoid polling or waits the faster your database runs the more concurrent transactions per second you will achieve. - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
On the topic of a more efficient busy handler, one approach I considered was to implement an event which was signalled when a database unlock occurred. That way, the busy handler could just wait on the event (which is an efficient wait state), and be guaranteed of a wake up when the lock is released (the event would be signalled at this time.) However, I wasn't at the time familiar enough with SQLite's innards to implement such a beast. Can anyone see any pitfalls to such an approach? Ian On 6/1/07, John Stanton <[EMAIL PROTECTED]> wrote: Tom Briggs wrote: > > >>I don't want to use >>other database, because I think Sqlite is great for an >>embedded system that I >>am using. > > >I think that your own questions about concurrency prove this > incorrect. If you need high concurrency and you don't like retries, > SQLite is not the database for you. > >-T > If you require ACID type data integrity and have a single disk there is no such thing as a "high concurrency database". They all share a single disk resource in some way. With Sqlite it is up to the designer to build in concurrency and that cna be done by single streaming. Better performance is achieved by using a single database connection so that cache hits are maximized. If your design is such that you never get a busy then you have an effective allocation of your disk resource. Using mutexes between threads and semaphores between processes gives you that capability. To my mind the only time you should use the busy logic is when you are working across a network with shared files. - To unsubscribe, send email to [EMAIL PROTECTED] -
RE: [sqlite] Concurrency
> If you require ACID type data integrity and have a single > disk there is > no such thing as a "high concurrency database". They all Then don't blame me if he's asking the wrong questions. :) -T - To unsubscribe, send email to [EMAIL PROTECTED] -
RE: [sqlite] Concurrency
I have no suggestions (I'm not an embedded systems guy), but your initial comment implied that there were other options. If there aren't then your original statement is invalid and there's nothing to discuss. :) -T > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: Friday, June 01, 2007 8:27 AM > To: sqlite-users@sqlite.org > Subject: RE: [sqlite] Concurrency > > Tom, > > > > I don't want to use > > > other database, because I think Sqlite is great for an > > > embedded system that I > > > am using. > > > >I think that your own questions about concurrency prove this > > incorrect. If you need high concurrency and you don't like retries, > > SQLite is not the database for you. > > Then what database would you suggest instead Sqlite for use > in embedded (low > memory, cpu: 200 Mhz) system? > __ > _ > Najhitrejši brezplačni klicni dostop :: Varno in zanesljivo > po internetu > Obiščite http://www.dialup386.com/ > > -- > --- > To unsubscribe, send email to [EMAIL PROTECTED] > -- > --- > > - To unsubscribe, send email to [EMAIL PROTECTED] -
RE: [sqlite] Concurrency
If option (b), using a single thread for writing and a multi-threaded write queue works in your situation, then that would probably provide best concurrency and performance. The only downside to this is the delayed writes mean you don't as easily get feedback to the original writer if a write fails (bad data for example). You could build delayed feedback/callback into the system, just depends on your application architecture. Also, I would strongly suggest doing some actual testing and confirming there is a bottleneck without any custom code to increase concurrency before programming workarounds for an expected problem. What we've found is that SQLite is so much faster than other databases (MSSQL in particular) that concurrency is greatly improved simply because each write is faster and thus the time the db is locked is less even though the whole db is locked. HTH, Sam --- We're Hiring! Seeking a passionate developer to join our team building products. Position is in the Washington D.C. metro area. If interested contact [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Friday, June 01, 2007 5:18 AM To: sqlite-users@sqlite.org Subject: [sqlite] Concurrency Hi, I am having a scenario where I have one reader/writer and many writer threads. All writers are pretty basic (single INSERT INTO; some sort of a logging info what a thread has done). I believe I will receive many BUSY return codes and I don't like these spinlock-like retries. The problem I am having with this design is that I would like to complete the thread ASAP, so that I don't have many threads idling and consuming resources of my embedded system. I was thinking to either: a. Use mutex/semaphore before writting to the database or b. Have a (thread safe) list of INSERT INTO strings that every writer thread populates and the main reader/writer thread later executes. Is this a good approach? Does anyone have a better design? I don't want to use other database, because I think Sqlite is great for an embedded system that I am using. - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: Re: [sqlite] sqlite3_open() fails on WinCE due to utf8ToUnicode / unicodeToU
On 6/1/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: Yes, I can rebuild the image, but i didn't find any UTF-8 code page. But it really looks like this code page is not installed, because I tried GetCPInfo(CP_ACP, ) and it failed with ERROR_INVALID_PARAMETER. Can you tell me where I can enable UTF-8 support. (hope this is not to offtopic). Sorry but never used the WinCE builder tool. Maybe someone here knows better. Regards, ~Nuno Lucas Regards, Daniel - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
Tom Briggs wrote: I don't want to use other database, because I think Sqlite is great for an embedded system that I am using. I think that your own questions about concurrency prove this incorrect. If you need high concurrency and you don't like retries, SQLite is not the database for you. -T If you require ACID type data integrity and have a single disk there is no such thing as a "high concurrency database". They all share a single disk resource in some way. With Sqlite it is up to the designer to build in concurrency and that cna be done by single streaming. Better performance is achieved by using a single database connection so that cache hits are maximized. If your design is such that you never get a busy then you have an effective allocation of your disk resource. Using mutexes between threads and semaphores between processes gives you that capability. To my mind the only time you should use the busy logic is when you are working across a network with shared files. - To unsubscribe, send email to [EMAIL PROTECTED] -
AW: Re: [sqlite] sqlite3_open() fails on WinCE due to utf8ToUnicode / unicodeToU
Hello Yes, I can rebuild the image, but i didn't find any UTF-8 code page. But it really looks like this code page is not installed, because I tried GetCPInfo(CP_ACP, ) and it failed with ERROR_INVALID_PARAMETER. Can you tell me where I can enable UTF-8 support. (hope this is not to offtopic). Regards, Daniel - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] Concurrency
We find that synchronizing access to database writes using a mutex works well. You could think of implementing read and write locks using the thread primitives and achieve a better result. If you do poll to resolve busy checks a spinlock is certainly a bad idea. When we use that approach we will yield the thread after each busy. [EMAIL PROTECTED] wrote: Hi, I am having a scenario where I have one reader/writer and many writer threads. All writers are pretty basic (single INSERT INTO; some sort of a logging info what a thread has done). I believe I will receive many BUSY return codes and I don't like these spinlock-like retries. The problem I am having with this design is that I would like to complete the thread ASAP, so that I don't have many threads idling and consuming resources of my embedded system. I was thinking to either: a. Use mutex/semaphore before writting to the database or b. Have a (thread safe) list of INSERT INTO strings that every writer thread populates and the main reader/writer thread later executes. Is this a good approach? Does anyone have a better design? I don't want to use other database, because I think Sqlite is great for an embedded system that I am using. ___ Najhitrejši brezplačni klicni dostop :: Varno in zanesljivo po internetu Obiščite http://www.dialup386.com/ - To unsubscribe, send email to [EMAIL PROTECTED] - - To unsubscribe, send email to [EMAIL PROTECTED] -
RE: [sqlite] Concurrency
Tom, > > I don't want to use > > other database, because I think Sqlite is great for an > > embedded system that I > > am using. > >I think that your own questions about concurrency prove this > incorrect. If you need high concurrency and you don't like retries, > SQLite is not the database for you. Then what database would you suggest instead Sqlite for use in embedded (low memory, cpu: 200 Mhz) system? ___ Najhitrejši brezplačni klicni dostop :: Varno in zanesljivo po internetu Obiščite http://www.dialup386.com/ - To unsubscribe, send email to [EMAIL PROTECTED] -
RE: [sqlite] Concurrency
> I don't want to use > other database, because I think Sqlite is great for an > embedded system that I > am using. I think that your own questions about concurrency prove this incorrect. If you need high concurrency and you don't like retries, SQLite is not the database for you. -T - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] sqlite3_open() fails on WinCE due to utf8ToUnicode / unicodeToUtf8
On 6/1/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: Hello It looks like there's a problem on WinCE operating system with the utf8ToUnicode() / unicodeToUtf8() conversion functions. No database can be opened by sqlite3_open() because thehes functions fail. Please have a look what happens there (location: os_win.c :) [...] If I use the CP_ACP flag, everthing works ok: nChar = MultiByteToWideChar(CP_ACP, 0, zFilename, -1, NULL, 0); Same failure probably in unicodeToUtf8() because it uses "WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, 0, 0, 0, 0);" My question: Is this a bug or is something wrong with my WinCE-Image? It probably means your WinCE OS image doesn't have UTF-8 support built-in, so you either have to make your own character set conversions or rebuild the OS image with that support (if you can change the image, that is). Regards, ~Nuno Lucas Version information SQLite 3.3.17 (also tried 3.3.13 and failed) WinCE 5.0 Regards Daniel - To unsubscribe, send email to [EMAIL PROTECTED] -
[sqlite] Concurrency
Hi, I am having a scenario where I have one reader/writer and many writer threads. All writers are pretty basic (single INSERT INTO; some sort of a logging info what a thread has done). I believe I will receive many BUSY return codes and I don't like these spinlock-like retries. The problem I am having with this design is that I would like to complete the thread ASAP, so that I don't have many threads idling and consuming resources of my embedded system. I was thinking to either: a. Use mutex/semaphore before writting to the database or b. Have a (thread safe) list of INSERT INTO strings that every writer thread populates and the main reader/writer thread later executes. Is this a good approach? Does anyone have a better design? I don't want to use other database, because I think Sqlite is great for an embedded system that I am using. ___ Najhitrejši brezplačni klicni dostop :: Varno in zanesljivo po internetu Obiščite http://www.dialup386.com/ - To unsubscribe, send email to [EMAIL PROTECTED] -
[sqlite] sqlite3_open() fails on WinCE due to utf8ToUnicode / unicodeToUtf8
Hello
It looks like there's a problem on WinCE operating system with the
utf8ToUnicode() / unicodeToUtf8() conversion functions. No database
can be opened by sqlite3_open() because thehes functions fail.
Please have a look what happens there (location: os_win.c :)
/*
** Convert a UTF-8 string to microsoft unicode (UTF-16?).
**
** Space to hold the returned string is obtained from
sqliteMalloc.
*/
static WCHAR *utf8ToUnicode(const char *zFilename){// ->->->
zFilename is "mydatabase.db"
int nChar;
WCHAR *zWideFilename;
nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, NULL, 0);
// ->->-> returns 0 here
zWideFilename = sqliteMalloc( nChar*sizeof(zWideFilename[0]) );
// ->->-> returns null pointer
if( zWideFilename==0 ){
return 0;
// ->->-> leaves function here
}
nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1,
zWideFilename, nChar);
if( nChar==0 ){
sqliteFree(zWideFilename);
zWideFilename = 0;
}
return zWideFilename;
}
If I use the CP_ACP flag, everthing works ok:
nChar = MultiByteToWideChar(CP_ACP, 0, zFilename, -1, NULL, 0);
Same failure probably in unicodeToUtf8() because it uses
"WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, 0, 0, 0, 0);"
My question:
Is this a bug or is something wrong with my WinCE-Image?
Version information
SQLite 3.3.17 (also tried 3.3.13 and failed)
WinCE 5.0
Regards
Daniel
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Re: [sqlite] file structure issue
Nuno and Vivien thanks for your replies. i will try that. wang On 5/23/07, Nuno Lucas <[EMAIL PROTECTED]> wrote: On 5/23/07, weiyang wang <[EMAIL PROTECTED]> wrote: > does anyone know how can i get the source codes with the early file > structure? (65 seperate files)? thanks in advance. Download the complete source code [1] and run "./configure" on it (you need a POSIX build system, like linux, cygwin or MSYS). After that is done, you should have all preprocessed files generated, so you can just copy them to where you want. Regards, ~Nuno Lucas [1] http://www.sqlite.org/sqlite-3.3.17.tar.gz > > wang > - To unsubscribe, send email to [EMAIL PROTECTED] -
