Re: [sqlite] C API - Parameterized Atomic Transactions

On Tue, 9 Aug 2016 17:09:39 -0300 Paulo Roberto wrote: > I would like something like this: > > "BEGIN EXCLUSIVE TRANSACTION;" > "SELECT counter FROM mytable WHERE counterid = ?;" > "UPDATE mytable SET counter=? WHERE counterid = ?;" > "COMMIT TRANSACTION;"

Re: [sqlite] C API - Parameterized Atomic Transactions

On Thu, Aug 11, 2016 at 4:34 AM, Paulo Roberto wrote: > Thank you very much, it worked! Just remember that exposing a SQL function that de-references a "user"-supplied integer value as a pointer is inherently unsafe. Anyone can select remember(val, 0) or select

Re: [sqlite] C API - Parameterized Atomic Transactions

Thank you very much, it worked! On Tue, Aug 9, 2016 at 11:49 PM, Richard Hipp wrote: > On 8/9/16, Paulo Roberto wrote: > > > > I found your solution pretty elegant and I tried to implement it. > > But after solving a lot of building issues with the

Re: [sqlite] C API - Parameterized Atomic Transactions

On 8/9/16, Paulo Roberto wrote: > > I found your solution pretty elegant and I tried to implement it. > But after solving a lot of building issues with the sqlite3ext header It does not have to be implemented as a loadable extension. Just copy the lines

Re: [sqlite] C API - Parameterized Atomic Transactions

Thank you for all the answers. Clemens, The counterid in my case is a text field and not an integer. That's why I need to sanitize. Clemens and Keith, As each of my process has its own connection to the database, I tried your solution using BEGIN IMMEDIATE and it worked successfully. Thank you.

Re: [sqlite] C API - Parameterized Atomic Transactions

> "BEGIN EXCLUSIVE TRANSACTION;" > "SELECT counter FROM mytable WHERE counterid = ?;" > "UPDATE mytable SET counter=? WHERE counterid = ?;" > "COMMIT TRANSACTION;" > I have a counter that I need to increment and get its previous value in one > operation. > To access this counter I must pass

Re: [sqlite] C API - Parameterized Atomic Transactions

On 8/9/16, Richard Hipp wrote: > Or, you could make remember() a two argument function: > >UPDATE mytable SET counter=remember(counter, $ptr)+1 WHERE counterid=$id > A sample implementation for this function can now been seen at

Re: [sqlite] C API - Parameterized Atomic Transactions

On 8/9/16, Richard Hipp wrote: > > UPDATE mytable SET counter=remember(counter)+1 WHERE counterid=? > Or, you could make remember() a two argument function: UPDATE mytable SET counter=remember(counter, $ptr)+1 WHERE counterid=$id Then bind $ptr to the address of the

Re: [sqlite] C API - Parameterized Atomic Transactions

On 8/9/16, Paulo Roberto wrote: > > I need some help to ... increment a counter and get its > former value. > My question is: Preparing 4 statements, binding then and calling > *sqlite3_step > *for each one of then in order, would have the expected atomic operation >

Re: [sqlite] C API - Parameterized Atomic Transactions

On 9 Aug 2016, at 9:09pm, Paulo Roberto wrote: > My question is: Preparing 4 statements, binding then and calling *sqlite3_step > *for each one of then in order, would have the expected atomic operation > behavior or not? You might be happier with BEGIN IMMEDIATE. No

Re: [sqlite] C API - Parameterized Atomic Transactions

Paulo Roberto wrote: > I need some help to do a simple operation, increment a counter and get its > former value. > I could have some race condition, so the transaction must be atomic. > > I also would like to use prepared statements to accomplish that, so I have > less effort sanitizing inputs.

[sqlite] C API - Parameterized Atomic Transactions

Hello, I need some help to do a simple operation, increment a counter and get its former value. I could have some race condition, so the transaction must be atomic. I also would like to use prepared statements to accomplish that, so I have less effort sanitizing inputs. My problem: I have a