Join Conditions

Question

Since we can not use the on new {left.fieldA, left.fieldB} equals new {right.fieldA, right.fieldB} syntax, is it ok to do this?

 

from ka in kursanpassungQuery

                                        join lvl2Bid in quoteLevelTicksFromBloomberg on ka.OrderStatus.Isin equals lvl2Bid.Isin
                                        where lvl2Bid.Exchange == ka.PrimaryExchangeId
                                        && lvl2Bid.Level == 2 && lvl2Bid.Type == QuoteTickType.LevelBid

Answer 1

Hi Stylus.vb,

It looks OK. You need to test it on your environment by yourself.

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Best Regards,
Peja

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Answer 2

Yes, you can use new{left.fieldA, left.fieldB} equals {right.fieldA, right.fieldB} ... at least in version 1.2. What version of StreamInsight are you using?

Where you may have an issue is with an enum (assuming that QuoteTickType.LevelBid is an enum) ... StreamInsight doesn't support enumerations. Instead, I typically declare as an int and have the value as a constant. You'll get the same "look" from a syntax perspective when doing straight comparisons although it isn't quite the same, especially with bitmask (flags) enumerations.

That said, when I am joining using where conditions as opposed to a join statement, I will typically place each where clause individually on a separate line ... the result is no different but I find it a bit clearer.

from ka in kursanpassungQuery
from lvl2Bid in quoteLevelTicksFromBloomberg 
	where ka.OrderStatus.Isin == lvl2Bid.Isin
	where lvl2Bid.Exchange == ka.PrimaryExchangeId
	where lvl2Bid.Level == 2 
	where lvl2Bid.Type == QuoteTickType.LevelBid

 

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DevBiker (aka J Sawyer)
My Blog
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