| License |
BSD License, same as PostgreSQL. |
| Function |
Load Balancing |
Since PGCluster is the synchronous replication
of a multi-master, it can acquire the same value even if it
refers to different Cluster DB. It is very suitable for load
balancing for reference system. |
| When the load of an updating process is high,
you may use partial replication feature to decentralize the
load. |
| Problem Handling |
Cluster server can be set up three or more machines.
When a problem occurs in Cluster DB, loader balancer and a replication
server will be separated from that machine, and continues service
using the other Cluster DBs. |
| Several replication server can be set up. When
an problem occurs at the replication server, Cluster DB automatically
changes connection to the standing-by replication server. |
| When all replication servers stop, Cluster DB
operates in stand-alone mode. There are two modes for stand-alone
mode: read only mode which only permits references, and read
write mode, which permits updating. |
| Several loader balancer can be set up, however,
they will not have the problem detection and switching over
functions that the loader balancer itself has. |
| Recovery |
When the Cluster DBs were started with a recovery
option, it will come back to a replication system after taking
the synchronization to master DB's data. If there are three
or more Cluster DBs, a query can be processed without stopping
service during recovery. |
| Replication |
Query-based |
The replication is done in query-based method.
|
| COPY |
Since data read from the COPY (FROM) command are
also replicated, the backup files which were created by pg_dump
can also be replicated. |
| NOW( ) |
When inserting the present time data with a NOW
function (ex. the NOW function is contained in the query, or
the default value of a table is being set to 'NOW'), that values
will also be replicated. The time will be the time of a replication
server. |
NEXTVAL( ),
SETVAL( ) |
The sequence operation function (nextval, setval)
will be replicated. |
| Serial type |
Since the order of INSERT processing is controlled
to become the same in each Cluster DB, serial type data is synchronized
as well. |
| Stored procedure |
The stored procedure accompanied by data update
is replicated. |
| Large Object |
The data of large object is replicated. |
| OID |
The OID is replicated only the large object. |
