Without it, transactions are executed in standard READ_COMMITED
mode, without snapshoting/row versioning, leading to update conflicts
under high concurrency.
MSSQL's substring() implementation is somehow silly/strict and unable to
perform implicit casts to integer both for the start and length parameters.
This hits Moodle badly because of another problems (MDL-23997) we decided
to cast to string all bound placeholders long ago.
So this commit just enforces the cast of the start and length parameters to
integer. And includes unit tests for using placeholders on all positions in
the sql_substr() method.
When insert_record is called and it doesn't find any columns
to insert data into, that is a dml_exception as you need at least
one column in the database to insert into it. This can happen
when you have created a zero column database table, or the table
does not exist.
Includes following fixes:
* support for MS SQL Server
* optional trimming of of oversized VARCHAR fields
* conversion to forms library
* full localisation
* other cleanup
The default value of scale should be null not false in mssql, that is the
standard with other DBs
0 is a valid value for scale, don't change it in oracle
List of changes:
* New OOP API using PHP namespace \core\session\.
* All handlers now update the sessions table consistently.
* Experimental DB session support in Oracle.
* Full support for session file handler (filesystem locking required).
* New option for alternative session directory.
* Official memcached session handler support.
* Workaround for memcached version with non-functional gc.
* Improved security - forced session id regeneration.
* Improved compatibility with recent PHP releases.
* Fixed borked CSS during install in debug mode.
* Switched to file based sessions in new installs.
* DB session setting disappears if DB does not support sessions.
* DB session setting disappears if session handler specified in config.php.
* Fast purging of sessions used in request only.
* No legacy distinction - file, database and memcached support the same functionality.
* Session handler name included in performance info.
* Fixed user_loggedin and user_loggedout event triggering.
* Other minor bugfixing and improvements.
* Fixed database session segfault if MUC disposed before $DB.
Limitations:
* Session access time is now updated right after session start.
* Support for $CFG->sessionlockloggedinonly was removed.
* First request does not update userid in sessions table.
* The timeouts may break badly if server hosting forces PHP.ini session settings.
* The session GC is a lot slower, we do not rely on external session timeouts.
* There cannot be any hooks triggered at the session write time.
* File and memcached handlers do not support session lock acquire timeouts.
* Some low level PHP session functions can not be used directly in Moodle code.
The addition of a port for the database means that an array
would be set regardless of whether it had any information or not.
The isset() function sees an array as being set and follows through
with the rest of the if statement concatenating a colon to the end
of the database host name and throwing a connection problem if no port
number is supplied.
The if statement has now been changed to if not empty. The empty
function does see zero as an empty value, but a port shouldn't have
a value of zero anyway.
Looping over large numbers of items with array_shift() is expensive.
Reverse the array and fetch items from the top of the pile.
Credit goes to Martin Langhoff for original mysqli fix.
This commit moves from the batch SCOPE_IDENTITY() way to return
the inserted ids to the OUTPUT alternative (supported and
recommended since 2005). Also the handling of possible return
values is improved, with all the alternatives leading to expected results.
