> On Mar 24, 2017, at 4:48 PM, Deon Brewis wrote:
>
> Yeah ok, if you take I/O hits then things like memory pre-fetching makes zero
> difference. We're more in the business of "You take a page fault" == "You buy
> more memory". Different level of performance requirements. (And glad that
> SQL
Hi,
I developing app server with sqlite as storage engine.
Sqlite have many settings combinations affecting concurrency please help me
to chose right settings for my task:
1. SQLITE_THREADSAFE 1 (serialized) vs SQLITE_THREADSAFE 2 (multithreaded)
My app server will execute each client request i
On 25 Mar 2017, at 7:14pm, Max Terentiev wrote:
> Sqlite have many settings combinations affecting concurrency please help me
> to chose right settings for my task
1. Leave SQLITE_THREADSAFE to the default setting.
2. Leave shared cache and uncommitted reads to the default settings.
Use WAL m
On Saturday, 25 March, 2017 13:15, Max Terentiev wrote:
> I developing app server with sqlite as storage engine.
> Sqlite have many settings combinations affecting concurrency please help
> me to chose right settings for my task:
> 1. SQLITE_THREADSAFE 1 (serialized) vs SQLITE_THREADSAFE 2 (
I would like to construct a SQLite database for one writer and one or more
reader connections. The writer will be updating various data tables which
occasionally trigger one or more row inserts in a command table named
'cmd'. This command table is being polled by the readers for new commands.
To
On 25 Mar 2017, at 10:52pm, petern wrote:
> CREATE TABLE cmd(opcode TEXT, params TEXT);
>
> Also assume each reader is in a different process which maintains its own
> open db connection over which it periodically executes the following
> command retrieval query,
>
> SELECT * FROM cmd WHERE ro
> Page faults aren’t necessarily due to swapping. If you read a memory-mapped
> file, the first access to any page will fault to disk. Since SQLite supports
> memory-mapping, I’d assume this can occur during a query — the column data
> returned by sqlite may point into mmap’ed pages. (Is that co
All good points. Yes, query by 'rowid > $lastCmdRowid' was the intent.
Is there something that can be done by the writer, like holding a BEGIN
EXCLUSIVE TRANSACTION open with PRAGMA read_uncommitted=0? Would that
block all readers or would they continue to get empty results from the
command tabl
On 3/25/17 6:52 PM, petern wrote:
I would like to construct a SQLite database for one writer and one or more
reader connections. The writer will be updating various data tables which
occasionally trigger one or more row inserts in a command table named
'cmd'. This command table is being polled
On 26 Mar 2017, at 2:35am, petern wrote:
> Is there something that can be done by the writer, like holding a BEGIN
> EXCLUSIVE TRANSACTION open with PRAGMA read_uncommitted=0? Would that
> block all readers or would they continue to get empty results from the
> command table? I suppose I could
On Saturday, 25 March, 2017 19:35, petern wrote:
> All good points. Yes, query by 'rowid > $lastCmdRowid' was the intent.
> Is there something that can be done by the writer, like holding a BEGIN
> EXCLUSIVE TRANSACTION open with PRAGMA read_uncommitted=0? Would that
> block all readers or wo
James K. Lowden wrote:
> I recently wrote a utility to produce simple reports.
>
> https://github.com/jklowden/sqlrpt
>
> Numeric columns are aligned on the decimal point and formatted
> with the thousands separator consistent with the locale.
>
> Wide text columns are formatted to fit nic
Thanks Simon.
Yes, the actual command table has other columns like a time stamp to allow
readers to join and restart asynchronously without losing state. The
concept of 'done' in this system is also not so clear to the readers
because command execution depends on the state of independent systems
On Mar 25, 2017, at 5:52 PM, petern wrote:
> So finally, here is the question. Is there a SQLite API way for reader
> connections to block and wait for a meaningful change, like a new row, in
> the 'cmd' table instead of madly polling and using up database concurrency
> resources? [Block with
Saturday, 25 March, 2017 23:44. petern wrote:
> Can anybody explain the purpose of
> http://sqlite.org/c3ref/busy_handler.html
> ? It seems the only practical use would be to allow the caller to give
> the engine a suggested lock deadline before SQLITE_BUSY is returned by
> sqlite3_exec or sqli
> On Mar 25, 2017, at 3:52 PM, petern wrote:
>
> So finally, here is the question. Is there a SQLite API way for reader
> connections to block and wait for a meaningful change, like a new row, in
> the 'cmd' table instead of madly polling and using up database concurrency
> resources? [Block w
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