On Fri, Feb 08, 2008 at 01:08:13PM +0530, Yuvaraj Athur Raghuvir wrote:
Finally, I have managed to get the Mbeddded example working in VC++ 2005 Express Edition on Windows XP ! Thanks to the folks in the mailing list. Use Case: MonetDB5 , Embedded Mode , SQL To move towards the application I intend to experiment on, I need some more information:
- How to make data durable? In the simple example, I tried
the following: a) First Run: Create table and insert rows. Select to check if everything is ok. b) Second Run: Only perform selection
I get an error in the second run.
- How to get meta data of the database?
a) I want to know the size of the tables and meta tables in the data base. In particular I am interested in seeing the growth of the database on addition of content.
The growth depends on your column types used. Ie if you use lets say integers, then each new row of 8 columns, would simply increase the storage requirements with 8 * 4 bytes. etc.
b) Typically, there is a master table in the database that records information of the schema persisted. What is the name of the Master Table and its schema in MonetDB?
You mean the table 'tables' ? A select * from tables gives you a list of all your tables. (see also schemas, columns , etc)
c) SQLite has an independent analyzer tool which dumps the state of the storage from which I can extract most of the data I need. Does MonetDB have a similar mechanism?
There is no storage analyzer for MonetDB.
~Yuva
code snippet >>>>>
dbh = embedded_sql (set, setlen); if (dbh == NULL || mapi_error(dbh)) die(dbh, hdl); /* switch off autocommit */ if (mapi_setAutocommit(dbh, 0) != MOK || mapi_error(dbh))
Okay here you disabled autocommit, which is fine.
die(dbh,NULL); if ((hdl = mapi_query(dbh, "create table emp" " (name varchar(20),age int)")) == NULL || mapi_error(dbh)) die(dbh, hdl); close_handle(dbh,hdl); for(i=0; i< 1000; i++) { char query[100]; _snprintf(query, 100,"insert into empvalues('user%d', %d)", i, (i % 82)); if ((hdl = mapi_query(dbh, query)) == NULL || mapi_error(dbh)) die(dbh, hdl); close_handle(dbh,hdl); }
But then I would expect an 'commit;' here.
if ((hdl = mapi_query(dbh, "select * from emp")) == NULL ||mapi_error(dbh)) die(dbh, hdl); i=0; while (mapi_fetch_row(hdl)) { char *age = mapi_fetch_field(hdl, 1); i= i+ atoi(age); } if (mapi_error(dbh)) die(dbh, hdl); close_handle(dbh,hdl); printf("The sum is %d \n",i); mapi_disconnect(dbh); return 0;
Niels
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