rserv/doc/eRserver.HOWTO


Nélio Alves Pereira Filho
nelio@ime.usp.br

+-------------------------------------------------------------------------+
|                Como Criar um ambiente de replicação rserv               |
+-------------------------------------------------------------------------+

Antes de qualquer coisa, os arquivos contidos no pacote do rserv desta 
desta documentação devem ser copiados para seus respectivos lugares. Por 
exemplo,
/bin/* -> /usr/lib/postgresql/bin/
/share/RServ.pm -> /usr/lib/postgresql/share/contrib/
/lib/rserv.so -> /usr/lib/postgresql/lib/

A documentação dos programas extras criados encontram-se no arquivo
eRserver.Changelog.


from: http://techdocs.postgresql.org/

HOWTO: Setting up RServ with PostgreSQL 7.0.3
Last updated 13th September 2001
by S.Gopi

http://techdocs.postgresql.org/techdocs/settinguprserv.php

        Please note that this document is not terribly accurate.
        See html documentation which comes with Rserv 0.3 or higher
        at http://www.rot13.org/~dpavlin/rserv.html to see why.
                                                -- Dobrica Pavlinusic


*** Creating the Master Database
(You can skip this if you already have one)

    createdb master

Then create whatever tables you want in this Master database (required), 
and any records you want (optional).

Let us go with pg_dump because Replication will happen only if table 
structures and record entries (if any) are similar for both master and 
slave databases at initial stage, otherwise it gives error while Replicating.

    pg_dump -d master -f master.dump


*** Creating the Slave Database

First we create the slave database then restore the table structures 
and records from the dump we created in the previous step.
    createdb slave
    psql slave

    slave=$ \i master.dump
    slave=$ \q (quit from psql)

After setting up both the Master and Slave Databases lets get into setting 
up the Replication process.


*** Setting up Replication Process

There are Four Steps you must carry out before starting Replication

    + Step 1: Initializing Master Database for Replication
    + Step 2: Initializing Slave Database for Replication
    + Step 3: Adding Tables and Columns that needs to be Replicated in 
              Master Database
    + Step 4: Adding Tables and Columns that needs to be Replicated in 
              Slave Database
      These must be same as Master Database.


Step 1: Initializing Master Database for Replication

From the Command line execute :

    /usr/lib/postgresql/bin/MasterInit master

This Process will create necessary tables and sequences used by Replication 
process in Master database.  These tables are used by the Replication process
for keeping track of replication.


Step 2: Initializing Slave Database for Replication

From the Command line execute :

    /usr/lib/postgresql/bin/SlaveInit slave

This process will create necessary tables in slave database, according to the 
author of RServ these are used for book keeping information (I don't know for 
what purpose these are used).


Step 3: Adding Tables and Columns that needs to be Replicated in Master 
        Database

From the Command line execute :

    /usr/lib/postgresql/bin/MasterAddTable master table_name column_name 

This will add necessary entries in rserv tables in master database.  Only 
tables which are added in this way will be replicated into mirror database.

You can give a specific column name in the table, there is no restriction 
on this in this version (0.1), athough the author's document says only this 
column will be replicated.  Useful Bug !!! :-) Any column changed in the 
table will be properly updated in the master database.

Repeat the above step for all the tables in master for which you want 
mirroring (real painful job)


Step 4: Adding Tables and Columns that needs to be Replicated in Slave Database

From the Command line execute :

    /usr/lib/postgresql/bin/SlaveAddTable slave table_name column_name

These tables and columns must be same as you did for master database (I don't 
know what will happen if you change something, you can test this functionality 
if you have time.  Just remember this is version 0.1 ;-))

Repeat the above step for all the tables in slave for which you want 
mirroring (another painful work)


Then what?......

You can start doing the replication now,

/usr/lib/postgresql/bin/Replicate master slave

That's it!  You have done it...  As a test, update some records in the master
database (add, modify, delete), then do the replication and check the Slave 
database, it must be a mirror of the Master.  If not check all the above 
process again and still nothing works out just email me.

Whenever You want to replicate just execute the command :

    Replicate master slave

Note:
After executing the Replicate command just ensure a "__Snapshot" file of 0 
bytes doesn't exist either in /usr/local/pgsql/bin/ or in your current 
directory.

When I checked, this file gets created only if the replication process fails 
for some reason (even if the program didn't show up any error messages, 
remember this is version 0.1)

P.S.

RServ is very easy to use once you have created the appropriate structures 
(that is the big task).RServ is just in its infancy and it may be buggy, so 
use it at your own risk.  For example, just try this :
Without doing MasterAddTable and SlaveAddTable try doing Replicate it will 
return without any error messages with no actual mirroring.

Now, do the MasterAddTable and SlaveAddTable process then try with Replicate 
this time it does replication but original entries in slave database 
(before SlaveAddTable entries) will never get updated, or some other crap 
will happen!!  Try updating some entries in master database and then 
replication you will go with surprises...

Enjoy...
1	dpavlin	1.1
2			Nélio Alves Pereira Filho
3			nelio@ime.usp.br
4
5			+-------------------------------------------------------------------------+
6			\| Como Criar um ambiente de replicação rserv \|
7			+-------------------------------------------------------------------------+
8
9			Antes de qualquer coisa, os arquivos contidos no pacote do rserv desta
10			desta documentação devem ser copiados para seus respectivos lugares. Por
11			exemplo,
12			/bin/* -> /usr/lib/postgresql/bin/
13			/share/RServ.pm -> /usr/lib/postgresql/share/contrib/
14			/lib/rserv.so -> /usr/lib/postgresql/lib/
15
16			A documentação dos programas extras criados encontram-se no arquivo
17			eRserver.Changelog.
18
19
20	dpavlin	1.2	from: http://techdocs.postgresql.org/
21
22			HOWTO: Setting up RServ with PostgreSQL 7.0.3
23			Last updated 13th September 2001
24			by S.Gopi
25
26			http://techdocs.postgresql.org/techdocs/settinguprserv.php
27
28	dpavlin	1.3	Please note that this document is not terribly accurate.
29			See html documentation which comes with Rserv 0.3 or higher
30			at http://www.rot13.org/~dpavlin/rserv.html to see why.
31			-- Dobrica Pavlinusic
32	dpavlin	1.1
33
34			*** Creating the Master Database
35			(You can skip this if you already have one)
36
37			createdb master
38
39			Then create whatever tables you want in this Master database (required),
40			and any records you want (optional).
41
42			Let us go with pg_dump because Replication will happen only if table
43			structures and record entries (if any) are similar for both master and
44			slave databases at initial stage, otherwise it gives error while Replicating.
45
46			pg_dump -d master -f master.dump
47
48
49			*** Creating the Slave Database
50
51			First we create the slave database then restore the table structures
52			and records from the dump we created in the previous step.
53			createdb slave
54			psql slave
55
56			slave=$ \i master.dump
57			slave=$ \q (quit from psql)
58
59			After setting up both the Master and Slave Databases lets get into setting
60			up the Replication process.
61
62
63			*** Setting up Replication Process
64
65			There are Four Steps you must carry out before starting Replication
66
67			+ Step 1: Initializing Master Database for Replication
68			+ Step 2: Initializing Slave Database for Replication
69			+ Step 3: Adding Tables and Columns that needs to be Replicated in
70			Master Database
71			+ Step 4: Adding Tables and Columns that needs to be Replicated in
72			Slave Database
73			These must be same as Master Database.
74
75
76			Step 1: Initializing Master Database for Replication
77
78			From the Command line execute :
79
80			/usr/lib/postgresql/bin/MasterInit master
81
82			This Process will create necessary tables and sequences used by Replication
83			process in Master database. These tables are used by the Replication process
84			for keeping track of replication.
85
86
87			Step 2: Initializing Slave Database for Replication
88
89			From the Command line execute :
90
91			/usr/lib/postgresql/bin/SlaveInit slave
92
93			This process will create necessary tables in slave database, according to the
94			author of RServ these are used for book keeping information (I don't know for
95			what purpose these are used).
96
97
98			Step 3: Adding Tables and Columns that needs to be Replicated in Master
99			Database
100
101			From the Command line execute :
102
103			/usr/lib/postgresql/bin/MasterAddTable master table_name column_name
104
105			This will add necessary entries in rserv tables in master database. Only
106			tables which are added in this way will be replicated into mirror database.
107
108			You can give a specific column name in the table, there is no restriction
109			on this in this version (0.1), athough the author's document says only this
110			column will be replicated. Useful Bug !!! :-) Any column changed in the
111			table will be properly updated in the master database.
112
113			Repeat the above step for all the tables in master for which you want
114			mirroring (real painful job)
115
116
117			Step 4: Adding Tables and Columns that needs to be Replicated in Slave Database
118
119			From the Command line execute :
120
121			/usr/lib/postgresql/bin/SlaveAddTable slave table_name column_name
122
123			These tables and columns must be same as you did for master database (I don't
124			know what will happen if you change something, you can test this functionality
125			if you have time. Just remember this is version 0.1 ;-))
126
127			Repeat the above step for all the tables in slave for which you want
128			mirroring (another painful work)
129
130
131			Then what?......
132
133			You can start doing the replication now,
134
135			/usr/lib/postgresql/bin/Replicate master slave
136
137			That's it! You have done it... As a test, update some records in the master
138			database (add, modify, delete), then do the replication and check the Slave
139			database, it must be a mirror of the Master. If not check all the above
140			process again and still nothing works out just email me.
141
142			Whenever You want to replicate just execute the command :
143
144			Replicate master slave
145
146			Note:
147			After executing the Replicate command just ensure a "__Snapshot" file of 0
148			bytes doesn't exist either in /usr/local/pgsql/bin/ or in your current
149			directory.
150
151			When I checked, this file gets created only if the replication process fails
152			for some reason (even if the program didn't show up any error messages,
153			remember this is version 0.1)
154
155			P.S.
156
157			RServ is very easy to use once you have created the appropriate structures
158			(that is the big task).RServ is just in its infancy and it may be buggy, so
159			use it at your own risk. For example, just try this :
160			Without doing MasterAddTable and SlaveAddTable try doing Replicate it will
161			return without any error messages with no actual mirroring.
162
163			Now, do the MasterAddTable and SlaveAddTable process then try with Replicate
164			this time it does replication but original entries in slave database
165			(before SlaveAddTable entries) will never get updated, or some other crap
166			will happen!! Try updating some entries in master database and then
167			replication you will go with surprises...
168
169			Enjoy...