On 2010-10-06 15:13, peter qin wrote: > Dear all, > Yesterday,I had done a test about the speed of MonetDB.I used > the example code make a test.the red part is my adding code.
I don't see any red, but I'm guessing you added the for loop inserting
10000 records.
There are two main reasons this is slow:
- There are 10000 interactions with the server. This takes time.
Normally the best way to enter data into MonetDB/SQL is to use the COPY
INTO command which can read from a CSV file.
- The server uses autocommit by default. That means, every query is a
separate transaction. You'll get a speed up if you first (before the
CREATE TABLE) call
update(dbh, "START TRANSACTION");
and after the for loop call
update(dbh, "COMMIT");
In this way you tell the server that the whole table creation and
filling is a single transaction, so you'll only get that overhead once.
> #include <mapilib/Mapi.h>
> #include <stdio.h>
> #include <stdlib.h>
>
> void die(Mapi dbh, MapiHdl hdl)
> {
> if (hdl != NULL) {
> mapi_explain_query(hdl, stderr);
> do {
> if (mapi_result_error(hdl) != NULL)
> mapi_explain_result(hdl, stderr);
> } while (mapi_next_result(hdl) == 1);
> mapi_close_handle(hdl);
> mapi_destroy(dbh);
> } else if (dbh != NULL) {
> mapi_explain(dbh, stderr);
> mapi_destroy(dbh);
> } else {
> fprintf(stderr, "command failed\n");
> }
> exit(-1);
> }
>
> MapiHdl query(Mapi dbh, char *q)
> {
> MapiHdl ret = NULL;
> if ((ret = mapi_query(dbh, q)) == NULL || mapi_error(dbh) != MOK)
> die(dbh, ret);
> return(ret);
> }
>
> void update(Mapi dbh, char *q)
> {
> MapiHdl ret = query(dbh, q);
> if (mapi_close_handle(ret) != MOK)
> die(dbh, ret);
> }
>
> int main(int argc, char *argv[])
> {
> Mapi dbh;
> MapiHdl hdl = NULL;
> char *name;
> char *age;
>
> dbh = mapi_connect("localhost", 50000, "monetdb", "monetdb",
> "sql", "demo");
> if (mapi_error(dbh))
> die(dbh, hdl);
>
> update(dbh, "CREATE TABLE emp (name VARCHAR(20), age INT)");
>
> for(int i = 0;i<10000;i++)
> {
> update(dbh, "INSERT INTO emp VALUES ('John', 23)");
> }
> //why this cast more then serveral minutes .can you help me?
>
> hdl = query(dbh, "SELECT * FROM emp");
>
> while (mapi_fetch_row(hdl)) {
> name = mapi_fetch_field(hdl, 0);
> age = mapi_fetch_field(hdl, 1);
> printf("%s is %s\n", name, age);
> }
>
> mapi_close_handle(hdl);
> mapi_destroy(dbh);
>
> return(0);
> }
>
> Peter Qin
> peterqin1...@gmail.com
>
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--
Sjoerd Mullender
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