rserv/doc/eRserver.HOWTO


NÃ©lio Alves Pereira Filho
nelio@ime.usp.br

+-------------------------------------------------------------------------+
|                Como Criar um ambiente de replicaÃ§Ã£o rserv               |
+-------------------------------------------------------------------------+

Antes de qualquer coisa, os arquivos contidos no pacote do rserv desta 
desta documentaÃ§Ã£o 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 documentaÃ§Ã£o dos programas extras criados encontram-se no arquivo
eRserver.Changelog.


Fonte: http://techdocs.postgresql.org/


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