This patch adds for "--ps-protocol" second execution
of queries "SELECT".
Also in this patch it is added ability to disable/enable
(--disable_ps2_protocol/--enable_ps2_protocol) second
execution for "--ps-prototocol" in testcases.
This change takes into account a column's GENERATED ALWAYS AS
expression dependcy on sql_mode's PAD_CHAR_TO_FULL_LENGTH and
NO_UNSIGNED_SUBTRACTION flags.
Indexed virtual columns as well as persistent generated columns are
now not allowed to have such dependencies to avoid inconsistent data
or index files on sql_mode changes.
So an error is now returned in cases like this:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v VARCHAR(5) AS (a) PERSISTENT -- CHAR->VARCHAR or CHAR->TEXT = ERROR
);
Functions RPAD() and RTRIM() can now remove dependency on
PAD_CHAR_TO_FULL_LENGTH. So this can be used instead:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v VARCHAR(5) AS (RTRIM(a)) PERSISTENT
);
Note, unlike CHAR->VARCHAR and CHAR->TEXT this still works,
not RPAD(a) is needed:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v CHAR(5) AS (a) PERSISTENT -- CHAR->CHAR is OK
);
More sql_mode flags may affect values of generated columns.
They will be addressed separately.
See comments in sql_mode.h for implementation details.
When updating a table with virtual BLOB columns, the following might
happen:
- an old record is read from the table, it has no virtual blob values
- update_virtual_fields() is run, vcol blob gets its value into the
record. But only a pointer to the value is in the table->record[0],
the value is in Field_blob::value String (but it doesn't have to be!
it can be in the record, if the column is just a copy of another
columns: ... b VARCHAR, c BLOB AS (b) ...)
- store_record(table,record[1]), old record now is in record[1]
- fill_record() prepares new values in record[0], vcol blob is updated,
new value replaces the old one in the Field_blob::value
- now both record[1] and record[0] have a pointer that points to the
*new* vcol blob value. Or record[1] has a pointer to nowhere if
Field_blob::value had to realloc.
To fix this I have introduced a new String object 'read_value' in
Field_blob. When updating virtual columns when a row has been read,
the allocated value is stored in 'read_value' instead of 'value'. The
allocated blobs for the new row is stored in 'value' as before.
I also made, as a safety precaution, the insert delayed handling of
blobs more general by using value to store strings instead of the
record. This ensures that virtual functions on delayed insert should
work in as in the case of normal insert.
Triggers are now properly updating the read, write and vcol maps for used
fields. This means that we don't need VCOL_UPDATE_FOR_READ_WRITE anymore
and there is no need for any other special handling of triggers in
update_virtual_fields().
To be able to test how many times virtual fields are invoked, I also
relaxed rules that one can use local (@) variables in DEFAULT and non
persistent virtual field expressions.
If triggers are used for an insert/update/delete statement than the values of
all virtual columns must be computed as any of them may be used by the triggers.
