Transactions that used more than one level would cause errors if
there were consecutive calls to start a transaction - because each
query executed would clear the flag indicating that a transaction
was already in progress.
The comment for the logic to reset the nesting level on a query was
indicating that DDL (data definition language) would not work within
a transaction. This is untrue, and the module itself uses a transaction
to alter table or field names. So this function has been converted to
a no-op, deprecated to be removed in version 3 of this module. It is
also no longer called upon each query.
There have been some maintenance tidyups around this area also by
abstracting the nested transaction flag manipulations into protected
functions.
Code in the field alteration logic had a queries defiend as strings to
begin and commit transactions involve with changing table or column names.
This was causing fatal errors as BEGIN is not a valid keyword within
a trasaction (see SQLite documentation excerpt below).
A new api has been introduced to deal with transactions programmatically,
and this module was updated to support this a few months ago. This is a
tidy up of some missed portions - consuming this API which correctly uses
SAVEPOINT when a nested transaction is required automatically.
https://www.sqlite.org/lang_transaction.html
Transactions created using BEGIN...COMMIT do not nest. For nested
transactions, use the SAVEPOINT and RELEASE commands.
Instead of using a custom "memory" key in the $databaseConfig
which never really got used this now allows someone to simply enable
in-memory databases by setting the path to ":memory:" or to use the
following environment variable:
define('SS_SQLITE_DATABASE_PATH', ':memory:');
In preparation for https://github.com/silverstripe/sapphire/pull/1319
Probably should accept this at the same time.
If someone knows of the relevant ALTER permissions in SQLite, feel free to implement.
As opposed to LIKE, the GLOB operator is case sensitive by default
in SQlite3. It uses "*" instead of "%" for wildcards,
which necessitated a new SearchFilter->getWildcard() method.
SQlite3 doesn't support per-term modifiers,
COLLATE BINARY LIKE is case insensitive by default
unless the field collation is set up accordingly.
There's connection-level modifiers (PRAGMA case_sensitive_like = true),
but that would affect all comparisators in the executed query.
While the SQLite3 module is predominantly used for testing,
its best to leave this decision to the code using it.
We should default to a conservative setting (slower, but persistent).
Also remove coupling to SapphireTest when setting this value.
Don't bother creating the directory if running in-memory.
