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
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...