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134 lines
4.4 KiB
Plaintext
134 lines
4.4 KiB
Plaintext
erServer demonstration implementation
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(c) 2000, Vadim Mikheev and Thomas Lockhart, PostgreSQL Inc.
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Version 0.1:
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Replicates a master database to a single slave database.
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Tested under Linux (Mandrake 7.2).
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Requirements:
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- PostgreSQL >= 7.0.X
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A separate Makefile is required for PostgreSQL 7.0.x and earlier
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- Perl5 and the PostgreSQL perl interface
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- TCL and the PostgreSQL tcl interface (for demo only)
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How to compile:
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- make all
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- make install
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Scripts and libraries are installed in places which are consistant
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with the way other contrib/ code is installed; underneath the core
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items in a contrib/ directory.
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The toolset:
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MasterInit dbname
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sets up structures and user-defined functions for a master
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database.
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SlaveInit dbname
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sets up structures for a slave database. Does not include triggers,
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but only bookkeeping tables.
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MasterAddTable dbname table column
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sets up triggers for the specified table and column. Note that this
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column must be updated for replication to occur.
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SlaveAddTable dbname table column
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sets up bookkeeping for the specified table and column.
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Replicate masterdb slavedb
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actually replicate changes from a master to single slave. Note that
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this must be repeated to replicate to multiple slaves, but the
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bookkeeping for each slave is handled separately so each can be
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updated at different times and with different sets of changes.
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GetSyncID [--noverbose] slavedb
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returns the last syncid the specified slave has seen. May be used
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in conjunction with SyncSyncID and CleanLog using the --noverbose
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option.
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MasterSync masterdb syncid
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registers a syncid with the specified master database. Used to
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propagate replication success back to the master database.
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CleanLog masterdb syncid
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removes obsolete entries in the master database replication log
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table up to the specified replication sequence number.
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Other utilities:
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PrepareSnapshot
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build a file of replication information from the specified masterdb.
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ApplySnapshot
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use a file of replication information to apply to the specified
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slavedb.
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How to run a demo:
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Run the InitRservTest script. It will create two local databases
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'master' & 'slave' with table 'test' in them. It accepts the following
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arguments:
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--help
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Print a usage message and quit.
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--user name
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Access the database with another username.
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--host name
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Access a remote database. Note that the shared library *must* be
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visible in the same path as installed on the build machine.
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masterdb
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slavedb
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Names of test databases. Defaults to 'master' and 'slave',
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respectively.
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Once the test databases are set up, simply updating the master table
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is sufficient to log a replication event. You can update the table
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test then run "Replicate master slave", or you can use the demo
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program RservTest.
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Run the tcl/tk GUI demo program, RservTest. It has a single window,
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which has four buttons and three data entry boxes.
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--------------------------------------------------
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| PostgreSQL Asynchronous Replication |
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| Master Slave |
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| < master > < slave > |
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| [ Update ] < > |
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| [ Replicate ] |
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| [ Show ] ____________ |
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| [ Quit ] |
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--------------------------------------------------
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The demo has the following behaviors:
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If you enter a string into the data entry field to the right of
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[Update], then that string will be used to either update the master
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database or to query the slave database.
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If you click [Update], then the string in the data entry box will be
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entered into the master database.
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If you click [Replicate], then all changes since the last replication
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will be propagated to the slave database.
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If you click [Show], then the slave database will be queried to find
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the string in the data entry box to the right of the [Update]
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button. If the string does not (yet) exist in the slave database, then
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"n/a" will appear to the right of the [Show] button. If the string
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does exist in the slave database, then it will be printed to the right
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of the [Show] button.
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Todo:
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1. Support for multiple slave servers.
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2. Explicit support for master/slave failover.
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3. More docs.
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