columns
Fixed confusing warning.
Quoting INSERT section of the manual:
----
Inserting NULL into a column that has been declared NOT NULL. For
multiple-row INSERT statements or INSERT INTO ... SELECT statements, the
column is set to the implicit default value for the column data type. This
is 0 for numeric types, the empty string ('') for string types, and the
"zero" value for date and time types. INSERT INTO ... SELECT statements are
handled the same way as multiple-row inserts because the server does not
examine the result set from the SELECT to see whether it returns a single
row. (For a single-row INSERT, no warning occurs when NULL is inserted into
a NOT NULL column. Instead, the statement fails with an error.)
----
This is also true for LOAD DATA INFILE. For INSERT user can specify
DEFAULT keyword as a value to set column default. There is no similiar
feature available for LOAD DATA INFILE.
The Item::tmp_table_field_from_field_type() function creates Field_datetime
object instead of Field_timestamp object for timestamp field thus always
changing data type is a tmp table is used.
The Field_blob object constructor which is used in the
Item::tmp_table_field_from_field_type() is always setting packlength field of
newly created blob to 4. This leads to changing fields data type for example
from the blob to the longblob if a temporary table is used.
The Item::make_string_field() function always converts Field_string objects
to Field_varstring objects. This leads to changing data type from the
char/binary to varchar/varbinary.
Added appropriate Field_timestamp object constructor for using in the
Item::tmp_table_field_from_field_type() function.
Added Field_blob object constructor which sets pack length according to
max_length argument.
The Item::tmp_table_field_from_field_type() function now creates
Field_timestamp object for a timestamp field.
The Item_type_holder::display_length() now returns correct NULL length NULL
length.
The Item::make_string_field() function now doesn't change Field_string to
Field_varstring in the case of Item_type_holder.
The Item::tmp_table_field_from_field_type() function now uses the Field_blob
constructor which sets packlength according to max_length.
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.
Bug#19022 "Memory bug when switching db during trigger execution"
Bug#17199 "Problem when view calls function from another database."
Bug#18444 "Fully qualified stored function names don't work correctly in
SELECT statements"
Documentation note: this patch introduces a change in behaviour of prepared
statements.
This patch adds a few new invariants with regard to how THD::db should
be used. These invariants should be preserved in future:
- one should never refer to THD::db by pointer and always make a deep copy
(strmake, strdup)
- one should never compare two databases by pointer, but use strncmp or
my_strncasecmp
- TABLE_LIST object table->db should be always initialized in the parser or
by creator of the object.
For prepared statements it means that if the current database is changed
after a statement is prepared, the database that was current at prepare
remains active. This also means that you can not prepare a statement that
implicitly refers to the current database if the latter is not set.
This is not documented, and therefore needs documentation. This is NOT a
change in behavior for almost all SQL statements except:
- ALTER TABLE t1 RENAME t2
- OPTIMIZE TABLE t1
- ANALYZE TABLE t1
- TRUNCATE TABLE t1 --
until this patch t1 or t2 could be evaluated at the first execution of
prepared statement.
CURRENT_DATABASE() still works OK and is evaluated at every execution
of prepared statement.
Note, that in stored routines this is not an issue as the default
database is the database of the stored procedure and "use" statement
is prohibited in stored routines.
This patch makes obsolete the use of check_db_used (it was never used in the
old code too) and all other places that check for table->db and assign it
from THD::db if it's NULL, except the parser.
How this patch was created: THD::{db,db_length} were replaced with a
LEX_STRING, THD::db. All the places that refer to THD::{db,db_length} were
manually checked and:
- if the place uses thd->db by pointer, it was fixed to make a deep copy
- if a place compared two db pointers, it was fixed to compare them by value
(via strcmp/my_strcasecmp, whatever was approproate)
Then this intermediate patch was used to write a smaller patch that does the
same thing but without a rename.
TODO in 5.1:
- remove check_db_used
- deploy THD::set_db in mysql_change_db
See also comments to individual files.
When a too long field is used for a key, only a prefix part of the field is
used. Length is reduced to the max key length allowed for storage. But if the
field have a multibyte charset it is possible to break multibyte char
sequence. This leads to the failed assertion in the innodb code and
server crash when a record is inserted.
The make_prepare_table() now aligns truncated key length to the boundary of
multibyte char.
- Fixed tests
- Optimized new code
- Fixed some unlikely core dumps
- Better bug fixes for:
- #14397 - OPTIMIZE TABLE with an open HANDLER causes a crash
- #14850 (ERROR 1062 when a quering a view using a Group By on a column that can be null
Problem #1: INSERT...SELECT, Version for 5.0.
Extended the unique table check by a check of lock data.
Merge sub-tables cannot be detected by doing name checks only.
Problem #1: INSERT...SELECT, Version for 4.1.
INSERT ... SELECT with the same table on both sides (hidden
below a MERGE table) does now work by buffering the select result.
The duplicate detection works now after open_and_lock_tables()
on the locks.
I did not find a test case that failed without the change in
sql_update.cc. I made the change anyway as it should in theory
fix a possible MERGE table problem with multi-table update.
produce warning for 'create database if not exists' if database exists
do not update database options in this case
produce warning for 'create table if not exists' if table exists
Item::tmp_table_field_from_field_type() and create_tmp_field_from_item()
was converting string field to blob depending on byte-wise length instead of
character length, which results in converting valid varchar string with
length == 86 to longtext.
Made that functions above take into account max width of character when
converting string fields to blobs.
