Brown, Daniel wrote:
> I just upgraded to the latest version (3.6.1) of the pre-processed C
> source code from the website, running the test again gives me similar
> results of 22.2 MB used and 24.55 MB high water from the same 9 MB file.
> Is there any way it could be the file that is causing the extra memory
> usage? I'll try rebuilding it next.
>
I just tried your test code with sqlite 3.6.1 amalgamation source on Win
XP and I get the following output from a 17.5 MB (18,362,368 bytes)
database file.
Entries.db Used: 18049 KB High: 20357 KB
I had to make a few changes to your code to get it to run. I have copied
the modified code below. This was built with Dev-Cpp using GCC 3.4.2.
There must be some other issue with your program that is causing the
inflated memory usage you are seeing.
Dennis Cote
#include <cstdlib>
#include <cstdio>
#include <sqlite3.h>
using namespace std;
int main(int argc, char *argv[])
{
sqlite3* pDataBase = NULL;
const char* ptail = NULL;
sqlite3_stmt* pstatement = NULL;
int result = -1;
int cmdSize = 0;
const int cmdBufferSize = 1024;
char cmdBuffer[cmdBufferSize];
const char* pdatabaseName = "file_db";
const char* pfilename = argv[1];
sqlite3_open( ":memory:", &pDataBase );
// create the attach command
cmdSize = sprintf( cmdBuffer, "ATTACH DATABASE '%s' AS %s", pfilename,
pdatabaseName );
// attach the on-disk database with ATTACH filename.db AS filename
result = sqlite3_exec( pDataBase, cmdBuffer, NULL, NULL, NULL );
// You can enumerate all tables in a your on-disk-file in the mentioned
scenario by
// doing a "SELECT tbl_name FROM filename.sqlite_master WHERE type =
'table'".
cmdSize = sprintf( cmdBuffer, "SELECT tbl_name FROM %s.sqlite_master
WHERE type = 'table'", pdatabaseName );
// prepare the statement
result = sqlite3_prepare_v2( pDataBase, cmdBuffer, cmdSize,
&pstatement, &ptail);
while( sqlite3_step( pstatement) == SQLITE_ROW)
{
// Then do a CREATE TABLE tableName AS SELECT * FROM
filename.tableName On each table in the file,
// thus creating an in-memory copy of the DB and having done a
select
on each table (i.e. you'll see how // much cache in memory
will be
used, etc.)
// get the table name
const unsigned char* pname = sqlite3_column_text( pstatement,
0);
// construct the command
cmdSize = sprintf( cmdBuffer, "CREATE TABLE %s AS SELECT * FROM
%s.%s", pname, pdatabaseName, pname );
result = sqlite3_exec( pDataBase, cmdBuffer, NULL, NULL, NULL );
}
sqlite3_finalize(pstatement);
// detach the attached database to leave just the in memory database
cmdSize = sprintf( cmdBuffer, "DETACH DATABASE %s", pdatabaseName );
result = sqlite3_exec( pDataBase, cmdBuffer, NULL, NULL, NULL );
sqlite_int64 memHigh = sqlite3_memory_highwater(0);
sqlite_int64 memUsed = sqlite3_memory_used();
printf("%s Used: %d KB High: %d KB\n", pfilename,
(int)(memUsed/1024), (int)(memHigh/1024));
sqlite3_close( pDataBase );
system("PAUSE");
return EXIT_SUCCESS;
}
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