If I understand SqlMaps documentation correcty, you can pass any number of columns from the "parent" ResultSet to the "child" selects. See chapter "Composite Keys or Multiple Complex Parameters Properties".Hello
I'm a bit confused about the right pattern to implement this kind of selects with ibatis.
This is the problem: I've got a select to search products in db. I'm using queryForList(java.lang.String id, java.lang.Object parameterObject, int skip, int max) to extract the first 100 records.
For every product extracted by this select I have to do other selects to get price/promotions/etc
This subselects take the product.cd as parameters and others parameters not in the column of the parent select but passed to the method searchProducts(Map pars), so I can't use construct like:
<result property="product" column="{id=PROD_CD}" select="getProdPrice"/>
because getProdPrice needs PROD_CD but also user.cdlist, user.cdcompany... am I wrong?
But in your case where you load 100 products (Always? If not, how often?), this lead to a severe case of the "1+N selects" pattern. The performance will most likely be unacceptable, as you will make 300 queries.
A better way is to do outer join to get related promotions and prices in the same result set. The mapping might be a bit tricky, though.
An even better way (33% faster than outer join in one rather unrepresentative test, but straight from production code) is to hash products by their key (I presume that's PROD_CD) with a queryForMap. Then load each class of related records with a queryForList, either by putting all key into the select (select * from promotion <iterate open="(" close=")" conjunction=", " prepend="where prod_cd in">#prodCdList[]#</iterate>) or by searching for the original products again (select * from protion where prod_cd in (select prod_cd from product where ...). This way you will make only 3 queries, but (unlike inner join) the driver won't have to transfer NULLs and duplicate "cells" for products.
Is rowHandler implementations the correct way to do this?
I suspect not, even though you gave no details about it...
Regards, Bostjan
