result
The IN function aggregates result types of all expressions. It uses that
type in comparison of left expression and expressions in right part.
This approach works in most cases. But let's consider the case when the
right part contains both strings and integers. In that case this approach may
cause wrong results because all strings which do not start with a digit are
evaluated as 0.
CASE uses the same approach when a CASE expression is given thus it's also
affected.
The idea behind this fix is to make IN function to compare expressions with
different result types differently. For example a string in the left
part will be compared as string with strings specified in right part and
will be converted to real for comparison to int or real items in the right
part.
A new function called collect_cmp_types() is added. It collects different
result types for comparison of first item in the provided list with each
other item in the list.
The Item_func_in class now can refer up to 5 cmp_item objects: 1 for each
result type for comparison purposes. cmp_item objects are allocated according
to found result types. The comparison of the left expression with any
right part expression is now based only on result types of these expressions.
The Item_func_case class is modified in the similar way when a CASE
expression is specified. Now it can allocate up to 5 cmp_item objects
to compare CASE expression with WHEN expressions of different types.
The comparison of the CASE expression with any WHEN expression now based only
on result types of these expressions.
Presence of a subquery in the ON expression of a join
should not block merging the view that contains this join.
Before this patch the such views were converted into
into temporary table views.
Select_type in the EXPLAIN output for the query SELECT * FROM t1 was
'SIMPLE', while for the query SELECT * FROM v1, where the view v1
was defined as SELECT * FROM t1, the EXPLAIN output contained 'PRIMARY'
for the select_type column.
When a view was used inside a trigger or a function, lock type for
tables used in a view was always set to READ (thus making the view
non-updatable), even if we were trying to update the view.
The solution is to set lock type properly.
User name (host name) has limit on length. The server code relies on these
limits when storing the names. The problem was that sometimes these limits
were not checked properly, so that could lead to buffer overflow.
The fix is to check length of user/host name in parser and if string is too
long, throw an error.
User name (host name) has limit on length. The server code relies on these
limits when storing the names. The problem was that sometimes these limits
were not checked properly, so that could lead to buffer overflow.
The fix is to check length of user/host name in parser and if string is too
long, throw an error.
SELECT right instead of INSERT right was required for an insert into to a view.
This wrong behaviour appeared after the fix for bug #20989. Its intention was
to ask only SELECT right for all tables except the very first for a complex
INSERT query. But that patch has done it in a wrong way and lead to asking
a wrong access right for an insert into a view.
The setup_tables_and_check_access() function now accepts two want_access
parameters. One will be used for the first table and the second for other
tables.
This bug is a side-effect of bug fix#16377. NOW() is optimized in
BETWEEN to integer constants to speed up query execution. When view is being
created it saves already modified query and thus becomes wrong.
The agg_cmp_type() function now substitutes constant result DATE/TIME functions
for their results only if the current query isn't CREATE VIEW or SHOW CREATE
VIEW.
When executing ALTER TABLE all the attributes of the view were overwritten.
This is contrary to the user's expectations.
So some of the view attributes are preserved now : namely security and
algorithm. This means that if they are not specified in ALTER VIEW
their values are preserved from CREATE VIEW instead of being defaulted.
When executing INSERT over a view with calculated columns it was assuming all
elements of the fields collection are actually Item_field instances.
This may not be true when inserting into a view and that view has columns that are
such expressions that allow updating (like setting a collation for example).
Corrected to access field information through the filed_for_view_update() function and
retrieve correctly the field info even for "update-friendly" non-Item_field items.
DESCRIBE returned the type BIGINT for a column of a view if the column
was specified by an expression over values of the type INT.
E.g. for the view defined as follows:
CREATE VIEW v1 SELECT COALESCE(f1,f2) FROM t1
DESCRIBE returned type BIGINT for the only column of the view if f1,f2 are
columns of the INT type.
At the same time DESCRIBE returned type INT for the only column of the table
defined by the statement:
CREATE TABLE t2 SELECT COALESCE(f1,f2) FROM t1.
This inconsistency was removed by the patch.
Now the code chooses between INT/BIGINT depending on the
precision of the aggregated column type.
Thus both DESCRIBE commands above returns type INT for v1 and t2.
When compiling INSERT statements the check whether columns are provided values
depends on the flag whether a field is used in that query (Field::query_id).
However the check for updatability of VIEW columns (check_view_insertability())
was calling fix_fields() and thus setting the Field::query_id even for the
view fields that are not referenced in the current INSERT statement.
So the correct check for columns without default values
( check_that_all_fields_are_given_values() ) is assuming that all the VIEW
columns were mentioned in the INSERT field list and was issuing no
warnings or errors.
Fixed check_view_insertability() to turn off the flag whether or not to set
Field::query_id (THREAD::set_query_id) before calling fix fields and restore
it when it's done.
Under row-based replication, DELETE FROM will now always be
replicated as individual row deletions, while TRUNCATE TABLE will
always be replicated as a statement.
When a CREATE TABLE command created a table from a materialized
view id does not inherit default values from the underlying table.
Moreover the temporary table used for the view materialization
does not inherit those default values.
In the case when the underlying table contained ENUM fields it caused
misleading error messages. In other cases the created table contained
wrong default values.
The code was modified to ensure inheritance of default values for
materialized views.
The convert_constant_item() function converts constant items to ints on
prepare phase to optimize execution speed. In this case it tries to evaluate
subselect which contains a derived table and is contained in a derived table.
All derived tables are filled only after all derived tables are prepared.
So evaluation of subselect with derived table at the prepare phase will
return a wrong result.
A new flag with_subselect is added to the Item class. It indicates that
expression which this item represents is a subselect or contains a subselect.
It is set to 0 by default. It is set to 1 in the Item_subselect constructor
for subselects.
For Item_func and Item_cond derived classes it is set after fixing any argument
in Item_func::fix_fields() and Item_cond::fix_fields accordingly.
The convert_constant_item() function now doesn't convert a constant item
if the with_subselect flag set in it.
The select statement that specified a view could be
slightly changed when the view was saved in a frm file.
In particular references to an alias name in the HAVING
clause could be substituted for the expression named by
this alias.
This could result in an error message for a query of
the form SELECT * FROM <view>. Yet no such message
appeared when executing the query specifying the view.
