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Minor wording improvements.

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Tom Lane 2006-12-01 03:19:48 +00:00
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doc/src/sgml/high-availability.sgml
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<!-- $PostgreSQL: pgsql/doc/src/sgml/high-availability.sgml,v 1.14 2006/11/22 18:15:34 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/high-availability.sgml,v 1.15 2006/12/01 03:19:48 tgl Exp $ -->
<chapter id="high-availability">
<title>High Availability and Load Balancing</title>
@ -12,7 +12,7 @@
<para>
Database servers can work together to allow a second server to
quickly take over quickly if the primary server fails (high
take over quickly if the primary server fails (high
availability), or to allow several computers to serve the same
data (load balancing). Ideally, database servers could work
together seamlessly. Web servers serving static web pages can
@ -50,8 +50,8 @@
committed until all servers have committed the transaction. This
guarantees that a failover will not lose any data and that all
load-balanced servers will return consistent results no matter
which server is queried. Asynchronous updating has a delay between
the time of commit and its propagation to the other servers,
which server is queried. In contrast, asynchronous solutions allow some
delay between the time of a commit and its propagation to the other servers,
opening the possibility that some transactions might be lost in
the switch to a backup server, and that load balanced servers
might return slightly stale results. Asynchronous communication
@ -101,7 +101,7 @@
standby server should never access the shared storage while
the primary server is running. It is also possible to use
some type of file system mirroring to keep the standby server
current, but the mirroring must be done in a way that the
current, but the mirroring must be done in a way that ensures the
standby server has a consistent copy of the file system.
</para>
@ -159,10 +159,10 @@ protocol to make nodes agree on a serializable transactional order.
<para>
With statement-based replication middleware, a program intercepts
every SQL query and sends it to all servers. Each server
operates independently. Read-only queries can be sent to a
single server because there is no need for all servers to
process it.
every SQL query and sends it to one or all servers. Each server
operates independently. Read-write queries are sent to all servers,
while read-only queries can be sent to just one server, allowing
the read workload to be distributed.
</para>
<para>