PostgreSQL database cluster: pgpool-II Tool

Pgpool-II (http://pgpool.projects.postgresql.org/ ) Is an intermediate Work in multiple PostgreSQL servers Services And PostgreSQL data Library Customer User Terminal .

We can look at pgpool as an intermediary. It provides the following functions:

Connection Connection Pool: Pgpool-ⅱ Storage Connection Connect to the PostgreSQL Server Services And reuse the new Connection Connect (out-of-the-box) User Name, Data Library , Protocol Version), reduce Connection Enabled Sales And improve the system Unified Overall throughput.

Copy: Pgpool-II can manage multiple PostgreSQL services . With the copy function, you can Real-time backup in 2 or more physical Magnetic Fields Disk Therefore When the disk fails, you do not need to stop the service.

Load Balance: If the data Library Is a copy, any server Services Server Executive Select Query Consult Returns the same End Result. Pgpool-ⅱ adopts a replication function Excellent Potential Yes to reduce multiple servers Services Device Room Select on allocation Query Consult Each PostgreSQL Server Services Of Load To improve the system Unified Overall throughput. PostgreSQL servers with the best performance improvement ratio Services The number of devices. In the same Time available Massive use User Of Query Load The best balance Executive Line.

Connection exceeded Limit passed : There is PostgreSQL And Connection Maximum number of connections After the number of connections exceeds Of Connection Rejected Absolutely . Set Set maximum Connection Number of connections, but Capital Source consumption and impact Unified Performance. Pgpool -II Yes Pair Max Connection Number of connections, Amount External Connection Connected Team Instead of returning immediately Error .

Parallel Query Consult : Use Parallelism Query Consult Function, data can be distributed across multiple servers Services So that Query Consult Yes Executive All row servers Services Same Hour Decrease Total Body Executive Line Time . Parallel Query Consult Work Hour Hou , Search Find the best big Rules Module data.

Pgpool-II is only available in Linux and Solaris Operation Operating System , FreeBSD And UNIX Unified Of Ring Application. Windows Unified No Corresponding .

Pgpool-II installation:

1. After decompression, configure

./Configure

2. install

Make

Make install

Pgpool-II Configuration

The configuration files of pgpool-II are/usr/local/etc/pgpool. conf and/usr/local/etc/PCP. conf.

Specific configuration reference official website (http://pgpool.projects.postgresql.org/pgpool-II/doc/pgpool- En.html ).

Advantages of pgpool

1. Do not modify the program

2. PHP, Perl, Java, and other languages can be operated without any language restrictions.

3. prefork Architecture

4. Restricted Access PostgreSQL Connections

5. Failover Shift Function

6. Configuration Copy Function

7. Configuration Now Load Balance

Disadvantages of pgpool

1. Increase system overhead

2. All. libpq protocols are not supported.

3. template1, regression, and other name databases Not mapped to the pool

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5. not deleted in time Prepare, reset_query_list after 8.3 Set Set Is "Discard All" Words Yes This Items Problem .   Address: http://www.dnbcw.com/biancheng/ SQL /fchg68958.html