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


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