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Add sqlite_progress_handler() API for specifying an progress callback (CVS 1111)

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FossilOrigin-Name: ddb364635a207658664ea92fc677cf16a143a938
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danielk1977
2003-10-18 09:37:26 +00:00
parent 4df92bbd44
commit 348bb5d6c8
9 changed files with 302 additions and 20 deletions
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28
www/c_interface.tcl
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@ -1,7 +1,7 @@
#
# Run this Tcl script to generate the sqlite.html file.
#
set rcsid {$Id: c_interface.tcl,v 1.38 2003/07/08 23:42:25 drh Exp $}
set rcsid {$Id: c_interface.tcl,v 1.39 2003/10/18 09:37:27 danielk1977 Exp $}
puts {<html>
<head>
@ -635,6 +635,8 @@ char *sqlite_vmprintf(const char *zFormat, va_list);
void sqlite_freemem(char*);
void sqlite_progress_handler(sqlite*, int, int (*)(void*), void*);
</pre></blockquote>
<p>All of the above definitions are included in the "sqlite.h"
@ -979,6 +981,30 @@ routine. The string pointer that these routines return should be freed
by passing it to <b>sqlite_freemem()</b>.
</p>
<h3>3.10 Performing background jobs during large queries </h2>
<p>The <b>sqlite_progress_handler()</b> routine can be used to register a
callback routine with an SQLite database to be invoked periodically during long
running calls to <b>sqlite_exec()</b>, <b>sqlite_step()</b> and the various
wrapper functions.
</p>
<p>The callback is invoked every N virtual machine operations, where N is
supplied as the second argument to <b>sqlite_progress_handler()</b>. The third
and fourth arguments to <b>sqlite_progress_handler()</b> are a pointer to the
routine to be invoked and a void pointer to be passed as the first argument to
it.
</p>
<p>The time taken to execute each virtual machine operation can vary based on
many factors. A typical value for a 1 GHz PC is between half and three million
per second but may be much higher or lower, depending on the query. As such it
is difficult to schedule background operations based on virtual machine
operations. Instead, it is recommended that a callback be scheduled relatively
frequently (say every 1000 instructions) and external timer routines used to
determine whether or not background jobs need to be run.
</p>
<a name="cfunc">
<h2>4.0 Adding New SQL Functions</h2>