mysql - Should I duplicate data in my DB? -

-

i have mysql db containing entry pages of website. let's has fields like:

table pages:  id  |  title  | content | date | author

each of pages can voted users, have 2 other tables

table users: id  |  name  | etc etc etc  table votes: id  |  id_user | id_page | vote

now, have page show list of pages (10-50 @ time) various information along average vote of page.

so, wondering if better to:

a) run query display pages (note heavy queries 3 tables) , each entry query calculate mean vote (or add 4th join main query?).

or

b) add "average vote" column pages table, update (along vote table) when user votes page.

nico

use database it's meant for; option far best bet. it's worth noting query isn't particularly heavy, joining 3 tables; sql excels @ sort of thing.

be cautious of sort of attempt @ premature optimization of sql; sql far more efficient @ people think is.

note benefit using option there's less code maintain, , less chance of data diverging code gets updated; it's lifecycle benefit, , they're ignored miniscule optimization benefits.


Comments

Post a Comment

Popular posts from this blog

android - Spacing between the stars of a rating bar? -

-
ho can set spacing beween stars? thats ratingbar: ratingbar = (ratingbar) inflater.inflate(r.layout.ratingbar, null); ratingbar.setlayoutparams(new layoutparams(layoutparams.wrap_content, layoutparams.wrap_content)); the layout: <?xml version="1.0" encoding="utf-8"?> <ratingbar xmlns:android="http://schemas.android.com/apk/res/android" style="@style/mystyle" android:layout_alignparentright="true" android:layout_height="19dp" android:layout_width="wrap_content" android:numstars="5"> </ratingbar> the style: <style name="mystyle" parent="@android:style/widget.ratingbar"> <item name="android:progressdrawable">@drawable/android_r2_ratingstar_yellow</item> <item name="android:indeterminatedrawable">@drawable/android_r2_ratingstar_grey</item> </style> thanks, cheers you have
Read more

aspxgridview - Devexpress grid - header filter does not work if column is initially hidden -

-
i'm using devexpress grid , i'm trying 'country' column display header filter properly: <dx:gridviewdatacolumn caption="country" fieldname="countryname" showincustomizationform="true" visible="false"> <settings allowheaderfilter="true"/> </dx:gridviewdatacolumn> if 'country' column set visible='true', header filter displayed should(it shows value option list). however, want 'country' column hidden, available in customization window(like in code above). in case, when column dragged outside customization window , grid , header filter clicked, javascript error encountered: element null element.addeventlistener(eventname, func, true); is known bug? there workarounds? set aspxgridview.settings.showheaderfilterbutton property true resolve problem. the following markup works fine me (i using dxperience 10.1.7): <asp:accessdatasource id="accessda
Read more

c# - How to execute a particular part of code asynchronously in a class -

-
i creating speech recognition engine that's going respond user commands.i have created button enable , disable speech recognition per user convenience.i have used dispose() of speech engine disable speech recoginition.here code private void button1_click(object sender, routedeventargs e) { engineon = !engineon; if (engineon) { speechengine = speech.createspeechengine(); //speech class creates , returns new speech engine. speechengine.audiolevelupdated += new eventhandler<audiolevelupdatedeventargs>(speechengine_audiolevelupdated); // use system's default microphone speechengine.setinputtodefaultaudiodevice(); speechengine.loadgrammar(new dictationgrammar()); // start listening speechengine.recognizeasync(recognizemode.multiple); } else { speechclass.myengine.dispose(); } } but disposal of speech obj
Read more