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Re: EOQualifier proper fetch across to-many?
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Re: EOQualifier proper fetch across to-many?


  • Subject: Re: EOQualifier proper fetch across to-many?
  • From: Kieran Kelleher <email@hidden>
  • Date: Tue, 06 Mar 2012 11:16:55 -0500

Whoa..... yes, YOU MUST create foreign key indexes yourself in MySQL! (The auto SQL from EntityModeler does not do it for you since creating true foreign key constraints in MySQL is a rat's nest of problems due to the lack of the most desired feature that MySQL lacks currently (deferred constraints)

Dump a schema (mysqldump --no-data > schema.sql) of your db and highlight all FKs that need indexes and create them asap ..... your performance on relationships will soar on larger tables.

As a rule, I create FK indexes on every table - would not give it a second thought not to create them.

Also, on the many-to-many relationship "join table", the default SQL will have created the compound PK using the two FK fields, however you should also create a INDEX with the two same keys in the opposite order..... for example, if your join table has two fields A and B, then the compound PK might be (A,B) in which case you need to add another index based on (B,A)

HTH, Kieran


On Mar 6, 2012, at 11:03 AM, Jesse Tayler wrote:

oh, the fetch kills the database alright -- I'll attempt to fix with indexes, but I've had mixed luck with that.

I notice there's not all the indexes I'd expect on foreign keys? mysql have anything funny there? or I should have at least an index for each foreign key, no?



On Mar 6, 2012, at 8:48 AM, Kieran Kelleher <email@hidden> wrote:

Prematurely looking for a fetch solution that does not overkill the database when the we don't know if the fetch overkills the database yet.  :-)

Regards Kieran
___________________________
Sent from my iPad.


On Mar 5, 2012, at 9:44 PM, Paul Yu <email@hidden> wrote:

Premature what?

-- 
Paul Yu
Sent with Sparrow

On Monday, March 5, 2012 at 8:55 PM, Kieran Kelleher wrote:




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  • Follow-Ups:
    • Re: EOQualifier proper fetch across to-many?
      • From: Kieran Kelleher <email@hidden>
References: 
 >EOQualifier proper fetch across to-many? (From: Jesse Tayler <email@hidden>)
 >Re: EOQualifier proper fetch across to-many? (From: Kieran Kelleher <email@hidden>)
 >Re: EOQualifier proper fetch across to-many? (From: Paul Yu <email@hidden>)
 >Re: EOQualifier proper fetch across to-many? (From: Kieran Kelleher <email@hidden>)
 >Re: EOQualifier proper fetch across to-many? (From: Jesse Tayler <email@hidden>)

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