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dpavlin |
1.1 |
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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Revision Log