Since Oracle 12, these statements (providing the same than the
well-known LIMIT clauses in MySQL and PostgreSQL) are available,
Just let's switch to use them, removing the old complex ROWNUM
based queries needed before to provide limits support.
This changes a couple of cases, in postgres and oracle where we
were trying to calculate strlen() on null values (that causes a
PHP 8.1 warning).
Also, at the same time, fixing another case in xmldb_field, it
was detected that it had a bug around precision (being set to the
value of type), being used as object property, when it's not, so
it was also fixed by moving the code logic a little bit.
Note that the bug has been there since inception because there
isn't any code in Moodle using that ->precision property. It
was just detected thanks to PHP 8.2, but that's another story. :-)
Verified that with the patch:
- All DBs can be installed (phpunit install)
- Both DDL and DML pass without any ddl/dml warning (in all DBs).
Standardises return patterns of null values across database types
to keep with sorting nullsto the top when ascending, and
to the bottom when descending
Sometimes, in order to provide a cross-db behaviour of unique indexes
mixing null and not null columns, we create, under the hood, some
function based indexes.
When that happens get_indexes() is returning the name of the
expression objects used to calculate that function index. But we need
the original column names to be able to compare indexes and get
column dependencies properly.
So, this patch just looks, when the index is unique and function based,
to the expressions (pretty standard CASE statements) and gets the
original column name from it.
Covered with tests.
This commit just:
- Moves the null => '' to better place, restricting it to PHP >= 7.0
(bug https://bugs.php.net/bug.php?id=72524)
- Adds a couple of notes here and there.
- Changes some small details to keep the file using the same coding.
These are our bugs actually - the oci docs are very clear that bound
params should be in-scope when oci_execute is called - and due to pass by value etc,
this was not true for our driver.
There is another bug that needed fixing - OCI barfs if null values are bound - this
can be avoided by setting them to '' which oci treats as null.
And finally - all our lob/clob/blob hacks were also binding to local "out-of-scope" vars.
While we already were detecting @ normalise_value()
both BLOBs and CLOBs properly on insert and update
statements (by introspectind the column specs), when
a long TEXT is being passed as part of an arbitrary
SQL, or within the conditions... it was being bound
as VARCHAR, leading to problems if used in combination
with DBMS_LOB functions.
This patch just ensures that any TEXT > 4000 bytes not
detected by normalise_value() will be, always, bound as CLOB,
unconditionally.
Covered with tests both covering its use with DBMS_LOB (the
reported bug) and also in general raw statements.
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.
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.
By using a pivoting strategy, we modify the list
of params (QM and NAMED supported) into a
subquery, so the 1000 limit in Oracle (ORA-01795)
is not thrown anymore.
