join or Mapping ?

[#1]

Hi,

Suppose i want to join two tables each having 2 columns and a column common in each , what should i perform left join or mapping ?

which is better performance wise ,,my feeling is mapping would be better.

[#2]

I feel that Join and Mapping are essentially different in terms of usage. While the result may be the same, the reason they are used is different.

Mapping should be primarily used when there is a 'if A, then (always) B' relation. For example,

Table 1:

Day, Person

Monday, A

Tuesday, B

Wednesday, C

Thursday, C

Friday, C

Saturday, C

Sunday, B

Table 2:

Person, Number

A, 1

B, 2

C, 3

If we want to get the value of 'Number' in Table 1, then mapping is used, because A always has the value of 1.

I am not sure about the performance of either method though. Maybe someone else can elaborate on that.

[#3]

I didnt understand that article completely , but from what i inferred from your statement is left join is preferred if less rows are present else mapping

[SunilChauhan]

according to that post  what i understand is mapping load in not optimized where as Join is optimized .