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Bug #30355: Incorrect ordering of UDF results

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There's currently no way of knowing the determinicity of an UDF.
And the optimizer and the sequence() UDFs were making wrong
assumptions about what the is_const member means.
Plus there was no implementation of update_system_tables()
causing the optimizer to overwrite the information returned by
the <udf>_init function.

Fixed by equating the assumptions about the semantics of 
is_const and providing a implementation of update_used_tables().
Added a TODO item for the UDF API change needed to make a better 
implementation.
This commit is contained in:
gkodinov/kgeorge@magare.gmz
2007-11-27 17:16:52 +02:00
parent 07b8373602
commit 8c3d5135ba
6 changed files with 112 additions and 6 deletions
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10
sql/udf_example.c
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@ -648,13 +648,11 @@ my_bool sequence_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
return 1;
}
bzero(initid->ptr,sizeof(longlong));
/*
Fool MySQL to think that this function is a constant
This will ensure that MySQL only evalutes the function
when the rows are sent to the client and not before any ORDER BY
clauses
/*
sequence() is a non-deterministic function : it has different value
even if called with the same arguments.
*/
initid->const_item=1;
initid->const_item=0;
return 0;
}