Commit 6cb8c8a0 authored by jhodgdon's avatar jhodgdon

Issue #1926758 by balsama, mitron: Fix code comment in system.module

parent e01afb83
......@@ -1907,17 +1907,18 @@ function system_init() {
// Ignore slave database servers for this request.
//
// In Drupal's distributed database structure, new data is written to the master
// and then propagated to the slave servers. This means there is a lag
// between when data is written to the master and when it is available on the slave.
// At these times, we will want to avoid using a slave server temporarily.
// For example, if a user posts a new node then we want to disable the slave
// server for that user temporarily to allow the slave server to catch up.
// That way, that user will see their changes immediately while for other
// users we still get the benefits of having a slave server, just with slightly
// stale data. Code that wants to disable the slave server should use the
// db_set_ignore_slave() function to set $_SESSION['ignore_slave_server'] to
// the timestamp after which the slave can be re-enabled.
// In Drupal's distributed database structure, new data is written to the
// master and then propagated to the slave servers. This means there is a
// lag between when data is written to the master and when it is available on
// the slave. At these times, we will want to avoid using a slave server
// temporarily. For example, if a user posts a new node then we want to
// disable the slave server for that user temporarily to allow the slave
// server to catch up. That way, that user will see their changes immediately
// while for other users we still get the benefits of having a slave server,
// just with slightly stale data. Code that wants to disable the slave
// server should use the db_ignore_slave() function to set
// $_SESSION['ignore_slave_server'] to the timestamp after which the slave
// can be re-enabled.
if (isset($_SESSION['ignore_slave_server'])) {
if ($_SESSION['ignore_slave_server'] >= REQUEST_TIME) {
Database::ignoreTarget('default', 'slave');
......
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