$dbr = wfGetDB( DB_SLAVE );
$res = $dbr->select( /* ...see docs... */ );
-while ( $row = $dbr->fetchObject( $res ) ) {
+foreach ( $res as $row ) {
...
}
-$dbr->freeResult( $res );
-
-Note the assignment operator in the while condition.
For a write query, use something like:
It's often the case that the best algorithm to use for a given task
depends on whether or not replication is in use. Due to our unabashed
Wikipedia-centrism, we often just use the replication-friendly version,
-but if you like, you can use $wgLoadBalancer->getServerCount() > 1 to
+but if you like, you can use wfGetLB()->getServerCount() > 1 to
check to see if replication is in use.
=== Lag ===
slave to catch up to that position before doing any reads from it. If
this wait times out, reads are allowed anyway, but the request is
considered to be in "lagged slave mode". Lagged slave mode can be
-checked by calling $wgLoadBalancer->getLaggedSlaveMode(). The only
+checked by calling wfGetLB()->getLaggedSlaveMode(). The only
practical consequence at present is a warning displayed in the page
footer.
UPDATE, or by using unique indexes in combination with INSERT IGNORE.
Then use the affected row count to see if the query succeeded.
+------------------------------------------------------------------------
+ Supported DBMSs
+------------------------------------------------------------------------
+
+MediaWiki is written primarily for use with MySQL. Queries are optimized
+for it and its schema is considered the canonical version. However,
+MediaWiki does support the following other DBMSs to varying degrees.
+
+* PostgreSQL
+* SQLite
+* Oracle
+* IBM DB2
+* MSSQL
+
+More information can be found about each of these databases (known issues,
+level of support, extra configuration) in the "databases" subdirectory in
+this folder.