Auto increment and unique id's

Hi,

The tables I was using were MySQL tables with auto-increment primary 
keys. As I have gathered now from earlier discussions, that does not 
work very well, so I started using the key-generation facilities instead.

* The generator did not notice that my tables had fields that were 
AUTO_INCREMENT. So, the code 'out of the box' did not really work. When 
I created fields (with id's that I set myself) the id's I specified were 
silently ignored. Bug there - should at least give warning at some point.

* Using ses.createWithGeneratedKey(meta) does not work out-of-the box 
either, despite documentation that it defaults to SSELECT_MAX - 
nullpointers were thrown (both mode and params are null). To solve that, 
I added the following to SFieldScalar:

    /**
     * If generator is not already configured,
     * this method initalizes this field to use Default generator mode, 
which is SSELECT_MAX
     * @return the mode
     */
   
    public SGeneratorMode getGeneratorModeOrDefault()
    {
        if(this.generatorMode == null && this.theGenerator == null)
            this.setGeneratorMode(SGeneratorMode.SSELECT_MAX,  
this.fieldName.concat("_seq_no").toLowerCase());
        return getGeneratorMode();
    }

And modified the SGenerator thus:

   public static  SGenerator theGenerator(SFieldScalar fld) {
        SGenerator gen = (SGenerator)fld.getTheGenerator();
        if (gen == null) {
+            switch (fld.getGeneratorModeOrDefault()) {
-            switch (fld.getGeneratorMode()) {
            case SSELECT_MAX:
                gen = new SGeneratorSelectMax(fld, 
(String)fld.getGeneratorParameter()[0]); break;
            case SSEQUENCE:
                gen = new SGeneratorSequence(fld, 
(String)fld.getGeneratorParameter()[0]); break;
            case SINSERT:
                gen = new SGeneratorInsertIdentity(fld, 
(String)fld.getGeneratorParameter()[0]); break;
            }       
        fld.setTheGenerator(gen);
        }
        return gen;
    }

Should I commit my fix ?

* Remaining question:  my fields are still AUTO_INCREMENT. But it works 
anyway, I guess since auto_increment sets exactly the value that 
SSELECT_MAX expects - they happen to correlate, which I guess is a prime 
candidate for future bugs. What is "The Best" way to handle this: Should 
I remove the AUTO_INCREMENT - property from the fields in MySql and rely 
only on the generator?


-- 
Martin Holst Swende ................. MSC Konsult AB
tel: +46(0)70 9519098 ............... Vasagatan 52
[email protected] .......... 111 20 Stockholm



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