This commit implements GH-8967.
SQLite supports multiple transaction modes. These include:
- DEFERRED (default) only acquires a lock when you start a read/write
- IMMEDIATE acquires a reserved lock
- EXCLUSIVE acquires an exclusive lock (stricter than immediate)
In WAL mode IMMEDIATE and EXCLUSIVE are identical.
One reason for wanting to specify a transaction mode is that SQLite
doesn't respect busy_timeout when a DEFERRED transaction tries to
upgrade a read lock to a write lock. Normally if you try to acquire a
lock and have busy_timeout configured, SQLite will wait for that period
until giving up and erroring out (SQLITE_BUSY). With DEFERRED, if you
have a transaction that first reads and there's a concurrent writer
while it's trying to upgrade to a write lock, you will immediately get
SQLITE_BUSY regardless of your busy_timeout.
Prior to this commit, the only available workarounds were:
- Using $pdo->exec("BEGIN IMMEDIATE TRANSACTION") instead of
$pdo->beginTransaction()
- Doing a dummy write at the start of each transaction so you don't get
stuck with a read lock
Both of those aren't very usable, especially in a framework context
where the user doesn't have complete control over how transactions are
started.
To address that, this commit adds four class constants to Pdo\Sqlite:
- ATTR_TRANSACTION_MODE -- a new attribute
- TRANSACTION_MODE_DEFERRED = 0
- TRANSACTION_MODE_IMMEDIATE = 1
- TRANSACTION_MODE_EXCLUSIVE = 2
These can be used as:
$pdo->setAttribute(
$pdo::ATTR_TRANSACTION_MODE,
$pdo::TRANSACTION_MODE_IMMEDIATE
);
1. Update: http://www.php.net/license/3_01.txt to https, as there is anyway server header "Location:" to https.
2. Update few license 3.0 to 3.01 as 3.0 states "php 5.1.1, 4.1.1, and earlier".
3. In some license comments is "at through the world-wide-web" while most is without "at", so deleted.
4. fixed indentation in some files before |
This attribute is a boolean value. It is taken from the return value of
sqlite3_stmt_readonly(), indicating if and only if the prepared statement makes
no direct changes to the content of the database.
The $Id$ keywords were used in Subversion where they can be substituted
with filename, last revision number change, last changed date, and last
user who changed it.
In Git this functionality is different and can be done with Git attribute
ident. These need to be defined manually for each file in the
.gitattributes file and are afterwards replaced with 40-character
hexadecimal blob object name which is based only on the particular file
contents.
This patch simplifies handling of $Id$ keywords by removing them since
they are not used anymore.
Features:
- native prepare/execute and bound parameters.
- finally supports binary data (via bound parameter api)
- full unicode/utf-8 support
Missing:
- UDF functions
- authorizer hooks for safe_mode/open_basedir restrictions
You need to download, compile and install sqlite3 yourself; we're not bundling
it (at least, not yet).
