The problem occurred when one had a subquery that had an equality X=Y where
Y referred to a named select list expression from the parent select. MySQL
crashed when trying to use the X=Y equality for ref-based access.
Fixed by allowing non-Item_field items in the described case.
The ROUND(X, D) function would change the Item::decimals field during
execution to achieve the effect of a dynamic number of decimal digits.
This caused a series of bugs:
Bug #30617:Round() function not working under some circumstances in InnoDB
Bug #33402:ROUND with decimal and non-constant cannot round to 0 decimal places
Bug #30889:filesort and order by with float/numeric crashes server
Fixed by never changing the number of shown digits for DECIMAL when
used with a nonconstant number of decimal digits.
Use compiler provided atomic builtins as a 'backend' for
MySQL's atomic primitives. The builtins are available on
a handful of platforms and compilers.
The name resolution for correlated subqueries and HAVING clauses
failed to distinguish which of two was being performed when there
was a reference to an outer aliased field.
Fixed by adding the condition that HAVING clause name resulotion
is being performed.
value when inserting into a view.
The mysql_prepare_insert function checks all fields of the target table that
directly or indirectly (through a view) are specified in the INSERT
statement to have a default value. This check can be skipped if the INSERT
statement doesn't mention any insert fields. In case of a view this allows
fields that aren't mentioned in the view to bypass the check.
Now fields of the target table are always checked to have a default value
when insert goes into a view.
columns (default datatype value is assigned).
The mysql_update function has been modified to generate
an error when trying to set a NOT NULL field to NULL rather than a warning
in the set_field_to_null_with_conversions function.
When resolving references we need to take into consideration
the view "fields" and allow qualified access to them.
Fixed by extending the reference resolution to process view
fields correctly.
server crash.
The filesort implementation has an optimization for subquery execution which
consists of reusing previously allocated buffers. In particular the call to
the read_buffpek_from_file function might be skipped when a big enough buffer
for buffer descriptors (buffpeks) is already allocated. Beside allocating
memory for buffpeks this function fills allocated buffer with data read from
disk. Skipping it might led to using an arbitrary memory as fields' data and
finally to a crash.
Now the read_buffpek_from_file function is always called. It allocates
new buffer only when necessary, but always fill it with correct data.
