c# - Entity Framework COUNT is doing a SELECT of all records -

-

profiling code because taking long time execute, generating select instead of count , there 20,000 records very slow.

this code:

var catviewmodel= new catviewmodel();  var catcontext = new catentities();  var cataccount = catcontext.account.single(c => c.accountid == accountid);  catviewmodel.numberofcats = cataccount.cats.count();

it straightforward stuff, code profiler showing is:

exec sp_executesql n'select  [extent1].xxxxx yyyyy,  [extent1].xxxxx yyyyy,  [extent1].xxxxx yyyyy,  [extent1].xxxxx yyyyy // idea [dbo].[cats] [extent1] cats.[accountid] = @entitykeyvalue1',n'@entitykeyvalue1 int',@entitykeyvalue1=7

i've never seen behaviour before, ideas?

edit: fixed if instead:

catviewmodel.numberofrecords = catcontext.cats.where(c => c.accountid == accountid).count();

i'd still know why former didn't work though.

so have 2 separate queries going on here , think can explain why different results. let's @ first one

// pull single account record var cataccount = catcontext.account.single(c => c.accountid == accountid); // count associated cat records against said account catviewmodel.numberofcats = cataccount.cats.count();

going on assumption cats has 0..* relationship account , assuming leveraging frameworks ability lazily load foreign tables first call cataccounts.cats going result in select associated cat records particular account. results in table being brought memory therefore call count() result in internal check of count property of in-memory collection (hence no count sql generated).

the second query

catviewmodel.numberofrecords =      catcontext.cats.where(c => c.accountid == accountid).count();

is directly against cats table (which iqueryable<t>) therefore operations performed against table where/count, , both of these evaluated on db-side before execution it's lot more efficient first.

however, if need both account , cats recommend eager load data on fetch, way take hit upfront once

var cataccount = catcontext.account.include(a => a.cats).single(...);

Comments

Post a Comment

Popular posts from this blog

database - VFP Grid + SQL server 2008 - grid not showing correctly -

-
i having problem, have grid called "gridbasica" , this: thisform.gridbase.recordsource = "sgviemp" sgviemp cursor made executing select sqlserver command sqlexec. when want modify registry, go form , the update there. so, when come form grid, grid isnt grid anymore, big white rectangle. reading around said: delete recordsource , asingt again. thisform.gridbase.recordsource = "" *--i sqlexe here thisform.gridbase.recordsource = "sgviemp" i , works, but, when click button modify again cursos updated modify form doesnt load fields did first time. could me out that? thanks in advance. --------------- edit ------------------ i have been doing recommended: lnselect = select(0) n = sqlexec(thisform.conexion,"select emp_ccodigo codigo, emp_cnombre 'nombre o razon social', emp_cnumrif 'r.i.f' sgviempr","sgviemp1") set echo on suspend select sgviemp zap in sgviemp *-- browse *--zaps correct
Read more

jquery - Set jPicker field to empty value -

-
im using jpicker color selector in form. have clear value set window/icon 'no color selected' state. i've tried following: $(':input[name="color"]').val(''); //access value directly. (does not affect jpicker) 2: $.jpicker.list[0].color.active.val('hex', '', this); //set color black , input value 000000, instead of empty string 3: $.jpicker.list[0].color.active.val(null, '', this); //does nothing none of 3 methods seems behave properly. in advance. this works me :) $.jpicker.list[0].color.active.val('v', null); here example: http://jsfiddle.net/3up7n/
Read more

.htaccess - htaccess convert request to clean url and add slash at the end of the url -

-
ok , searched more 4 days , more 20 posts here in stach or in websites without kind of success first here htaccess file rewriteengine on rewriterule ^([a-za-z0-9_]+)/?$ index.php?page=$1 [nc] rewriterule ^([a-za-z0-9_]+)\/([a-za-z0-9_]+)\/?$ index.php?page=$1&action=$2 [nc] i tried many codes 1 worked me can call request , works me www.example.com/pagename => www.example.com/index.php?page=pagename here questions , please provide me information "in detail" understand code well 1- how convert request automatically www.example.com/index.php?page=pagename www.example.com/pagename 2- if tried add slash @ end shows me page without images or styling mean www.example.com/pagename => works www.example.com/pagename/ => doesn't work that's :) for first part need 301 rule this: rewritecond %{the_request} /index\.php\?page=([^\s&]+) [nc] rewriterule ^ /%1? [r=301,l] for second part use absolute path in css, js, images files r
Read more