Hi!
I have 6-7 tables total containing subobjects for different objects like phonenumbers and emails for contacts.
This meaning i have to do some querys on each detailpage. I will use stored proc for fetching subobjects.
My question therefore was: if i could merge subobjects into same tables making me use perhaps 2 querys instead of 4 and thus perhaps doubling the size
of the tables would this have a possibility of giving me any performance difference whatsoever?
As i see pros arefewer querys, and cons are larger tables and i will need another field separating the types of objects in the table.
Anyone have insight to this?
I would be curious to see what you mean by "subobjects" - usually when you ask a question like this it is a good idea to post your table structure. You'll get more specific help that way.
In general, you should strive for proper normalization of your database. This normally means more tables, and the tables are thin, not wide. However, if you have similar sets of data that can be "typed" and placed into the same table, that is normally a good route to take. For example, if you have a business phone numbers and home phone numbers, I would recommend putting these in the same table and adding a field to specify its type, rather than having two separate tables. On the other hand, you shouldn't try to squeeze more disparate types of data into the same table and type them.
|||By objects i mean like applications, users, groups.
By subobjects i mean phonenumbers, emails, contacts(for example when an application have a number of contacts linked to it) etc
To illustrate i post some of my tables:
First an object table:
CREATE TABLE [sw20aut].[sw_apps] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[kund_id] [int] NOT NULL ,
[namn] [varchar] (80) COLLATE Finnish_Swedish_CI_AS NOT NULL ,
[beskrivning] [text] COLLATE Finnish_Swedish_CI_AS NOT NULL DEFAULT ('') ,
[usr_rubrik] [varchar] (60) COLLATE Finnish_Swedish_CI_AS NOT NULL DEFAULT ('Övrig information') ,
[usr_information] [text] COLLATE Finnish_Swedish_CI_AS NOT NULL DEFAULT ('') ,
[kat] [int] NOT NULL DEFAULT('0') ,
[typ] [tinyint] NOT NULL DEFAULT('0') ,
[skapare] [varchar] (15) COLLATE Finnish_Swedish_CI_AS NOT NULL ,
[skapad] [datetime] NOT NULL ,
[del] [bit] NOT NULL DEFAULT ('0')
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
Here are some subtables:
CREATE TABLE [sw20aut].[sw_sub_email] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[p_typ] [varchar] (3) COLLATE Finnish_Swedish_CI_AS NOT NULL ,
[p_id] [int] NOT NULL ,
[epost] [varchar] (60) COLLATE Finnish_Swedish_CI_AS NULL ,
[kommentar] [varchar] (60) COLLATE Finnish_Swedish_CI_AS NOT NULL
) ON [PRIMARY]
CREATE TABLE [sw20aut].[sw_sub_phone] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[p_typ] [varchar] (3) COLLATE Finnish_Swedish_CI_AS NOT NULL ,
[p_id] [int] NOT NULL ,
[tel_land] [varchar] (6) COLLATE Finnish_Swedish_CI_AS NULL ,
[tel_rikt] [varchar] (6) COLLATE Finnish_Swedish_CI_AS NULL ,
[tel_nr] [varchar] (30) COLLATE Finnish_Swedish_CI_AS NULL ,
[kommentar] [varchar] (60) COLLATE Finnish_Swedish_CI_AS NOT NULL
) ON [PRIMARY]
CREATE TABLE [sw20aut].[sw_sub_contacts] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[p_typ] [varchar] (3) COLLATE Finnish_Swedish_CI_AS NOT NULL ,
[p_id] [int] NOT NULL ,
[kon_id] [int] NOT NULL ,
[kon_kid] [int] NOT NULL ,
[kommentar] [varchar] (60) COLLATE Finnish_Swedish_CI_AS NOT NULL
) ON [PRIMARY]
CREATE TABLE [sw20aut].[sw_sub_grupper] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[p_typ] [varchar] (3) COLLATE Finnish_Swedish_CI_AS NOT NULL ,
[p_id] [int] NOT NULL ,
[grp_id] [int] NOT NULL ,
[grp_kid] [int] NOT NULL ,
[kommentar] [varchar] (60) COLLATE Finnish_Swedish_CI_AS NOT NULL
) ON [PRIMARY]
p_id = the parents id
p_typ = type of parent, for example app, con or grp
As seen above i could join sub_contacts and sub_groups easily(need another field to set if its a contact or group though) and i could probably join email and phone as well, in worst case using some kind of commaseparated format to separate countrycode, areacode etc. I have a couple of other similar sub tables as well The question is if it could be worth the effort or the larger tables(more rows) and another field to sort by would negate the advantage of fewer querys when listing? Practically it would mean a step from 6-7 querys on worst pages down to 3-4.
I use batched dynamic querys and some stored procs depending on circumstances
The baseline for the table definition is files and association so if what I am seeing is correct you have maybe one or two secondary tables and the relationship is actually quantified by upper and lower bound Cardinality meaning number of expected rows. And I don't think name should be VarChar 80 more like 30-50. Try the links below for functional dependency and free tables you can clone. Hope this helps.
http://www.databaseanswers.org/data_models/
http://www.utexas.edu/its/windows/database/datamodeling/rm/rm7.html
|||The problem regarding sizeing the name columns in different tables are partly because i will have to import data from old tables used by the former application.
These tables are very poorly designed(even to my standards ;) ) and have caused users to add more than just name in the namefields so forth. I will control this better programatically but
nevertheless stripping of existing text in the field would not be popular so my thought weher to implement it and try steering all new information in a better way.
I think that this meant i needed that size when examining the old data to prevent truncation.
Anyway the tables above are examples i have more secondary tables and quite a few primary tables as well.
The basic concept i was thinking about if its better practice to have larger tables wich results in less querys / page (merging the sub/secondary tables as much as practically possible) or using smaller, slicker tables and more inpage querys/procs. For example using 1 table to link both contacts and groups and 1 table for perhaps phone/email and even links as long as one can reuse the fields not resulting in empty fields.
Shall check your links btw
|||You could clean the data before importing it and I am concerned you are describing tables on the Calculus end where you have main table and the dimenssions on this end tables sizes should be similar. I know you can use validators but you can also use CHECK CONSTRAINT on you columns so people cannot insert whatever they like in name columns.
http://msdn2.microsoft.com/en-us/library/ms188258.aspx
