The code that set up data to be passed to user-defined functions was very
old and analyzed the "Type" of the data that was passed into the UDF, when
it really should analyze the "return_type", which is hard-coded for simple
Items and works correctly for complex ones like functions.
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Added test at Sergei's behest.
The problem was that the grammar allows to create a function with an optional
definer clause, and define it as a UDF with the SONAME keyword.
Such combination should be reported as an error.
The solution is to not change the grammar itself, and to introduce a
specific check in the yacc actions in 'create_function_tail' for UDF,
that now reports ER_WRONG_USAGE when using both DEFINER and SONAME.
When there is no index defined filesort is used to sort the result of a
query. If there is a function in the select list and the result set should be
ordered by it's value then this function will be evaluated twice. First time to
get the value of the sort key and second time to send its value to a user.
This happens because filesort when sorts a table remembers only values of its
fields but not values of functions.
All functions are affected. But taking into account that SP and UDF functions
can be both expensive and non-deterministic a temporary table should be used
to store their results and then sort it to avoid twice SP evaluation and to
get a correct result.
If an expression referenced in an ORDER clause contains a SP or UDF
function, force the use of a temporary table.
A new Item_processor function called func_type_checker_processor is added
to check whether the expression contains a function of a particular type.
The is_null value was initialized once and thereafter only set to indicate
NULL, and never unset to indicate not-NULL.
Now set is_null to false, in addition to only setting it to true when the value
in question is null.
- Pass "buffers[i]" to val_str() in udf_handler::fix_fields insteead of NULL.
- Add testcase for UDF that will load and run the udf_example functions
if available
