优化DB2查询-如何从bigint转换为varchar/char？

Question

我试图在DB2中优化这个查询。选择url关键字的内部查询将查询时间从15秒到大约10分钟。我已经找到了这个问题，这似乎是因为比较'where tracked = c.catentry_id‘是比较varchar字段(’ve关键字)和bigint字段。如果我修改它以将varachar与字符串值进行比较，它就会变得更快。我的问题是：

从bigint到varchar转换c.catentry_id的语法是什么？(我想如果我能做到这一点，它就能解决它)

 select 
                    xmlelement(NAME "Products",xmlagg(xmlrow(c.field5 as "ExternalId",
                    cd.name as "Name",
                    cg.identifier as "CategoryExternalId",
                    concat('@bv.base.image.url@', cd.thumbnail) as "ImageUrl",


    (select urlkeyword from seourl s
                        inner join seourlkeyword sk
                        on s.seourl_id = sk.seourl_id
                        where urlkeyword = c.catentry_id

) as "ProductPageUrl",              
                    mfpartnumber as "ManufacturerPartNumber",
                    cd.shortdescription as "Description",
                    c.field1 as "BrandExternalId" option row "Product"))) as xml_document

                    from catentry c 
                    inner join catentdesc cd
                    on c.catentry_id = cd.catentry_id and cd.language_id = -1
                    inner join catgpenrel cgp 
                    on c.catentry_id = cgp.catentry_id
                    inner join catgroup cg
                    on cg.catgroup_id = cgp.catgroup_id
                    where cgp.catalog_id in
                   (select catalog_id from catalog where identifier = 'Web_OW Default Web')

Answer 1

你可以试试这个

where urlkeyword = CAST(c.catentry_id AS VARCHAR(n))

显然，您需要在you关键字字段的长度中替换n。

但是，我认为这个问题涉及到索引正确的表。

希望这能帮到你。