From: | sarlav kumar <sarlavk(at)yahoo(dot)com> |
---|---|
To: | pgsqlperform <pgsql-performance(at)postgresql(dot)org>, pgsql-novice(at)postgresql(dot)org |
Subject: | INSERT question |
Date: | 2004-12-13 16:28:39 |
Message-ID: | 20041213162839.60931.qmail@web51303.mail.yahoo.com |
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Thread: | |
Lists: | pgsql-novice pgsql-performance |
Hi All,
I have a question regarding multiple inserts.
The following function inserts for each country found in country table, values into merchant_buyer_country.
----------------------------------------------------------------------------------------------------------------------------------------
CSQLStatement st( sql );
CSQLStatement st1( sql );
SQLINTEGER rows;
long num_codes = 0;
rows = st.Select( "SELECT * FROM merchant_buyer_country where merchant_id = %lu ",merchant_id );
if ( rows )
return 0;
char code[4];
rows = st.Select( "SELECT code FROM country WHERE send IS NOT NULL OR receive IS NOT NULL" );
SQLBindCol( st.hstmt, 1, SQL_C_CHAR, code, sizeof(code), 0 );
long i;
for (i = 0; i < rows; i++ )
{
st.Fetch();
st1.Command("INSERT INTO merchant_buyer_country (merchant_id,country,enabled,group_id) VALUES(%lu ,'%s', true, %lu )", merchant_id,
code,group_id);
}
st.CloseCursor();
st1.CloseCursor();
return 1;
----------------------------------------------------------------------------------------------------------------------------------------
On looking at the log file, I saw separate inserts being performed, and each insert takes about 1 second.
insert into merchant_buyer_country (merchant_id,country,enabled,group_id) values(1203,'IN','true',1);
insert into merchant_buyer_country merchant_id,country,enabled,group_id) values(1203,'US','true',1);
insert into merchant_buyer_country merchant_id,country,enabled,group_id) values (1203,'AR','true',1);
insert into merchant_buyer_country (merchant_id,country,enabled,group_id) values(1203,'AZ','true',1);
insert into merchant_buyer_country merchant_id,country,enabled,group_id) values (1203,'BG','true',1);
insert into merchant_buyer_country merchant_id,country,enabled,group_id) values(1203,'SP','true',1);
.....
There are more than 100 countries and this takes a lot of time for the inserts to complete.
Is there a way to write the INSERT as follows?
INSERT into merchant_buyer_country (merchant_id,country,enabled,group_id) values (1203,
(SELECT code FROM country WHERE send IS NOT NULL OR receive IS NOT NULL), 'true',1);
I tried this, but I get the following problem:
ERROR: More than one tuple returned by a subselect used as an expression.
I know there is a way to this, but I am not sure where I am going wrong. Can someone please help me figure this out.
Thanks,
Saranya
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