Hi guys,
I'm using database with more than 250 tables. This database is allocated at the 3 different geographic locations. Backup file of this database is quite large (about 4,5 the GB). For the connection between my three servers (for now just 3) I use the VPN through the Internet. Capacity of this link is 256kb, therefore very small. Following the instructions in the DBReplicator Users Manual, after creating subscriber, user needs to getting (??) the snapshot, in order to start using identical databases. In consideration of the parameters listed above, I'm not able, for the reasonable time, to get snapshot from "main" server to second and third ones.
My question: is it snapshot necessary?
I'm able to ensure all databases start working with equal data, using the backup/restore options of the database, so I don't need getting snapshot. Am I right? How to start repliaction data without to getting snapshot before? Is this possible using DBReplicator?
I'm using:
PostgreSQL 8.2.12
WindowsServer 2003 / 2008
JRE 1.05_14
Regards
Djordje
Re:is the snapshot necessary?
Dear Djorge,
If you with 250 table, 3 Servers. I was with 167 Tables, 9 Servers with 10Gigs Tablespace in Oracle 9i
I was import the dump file from 4 Gigs dmp file (exported from oracle).
I spent about 1.5-2 hours to do Snapshot completely among 2 servers.
I try to explain This Snapshot Mechanism such the way (based on my observation in my installation experience):
1. DBReplicator convert all data to from Both in Subscription Server and in Publication Server into XML format i..it takes about 30 minutes-1 hour..
2. then DBReplicator MOVES those converted that XML 1 file to Subscription server ,DBRep engine making sure the database structure and data are the same in Pub and Sub..so if there any CHANGE to one record and you do the Push/Pull manualy or automatically (scheduled) the DBRep engine will WRITE it also into the XML file reside.
3.Then the engine will send data to another XML and make sure the both XML are the same..
4. then the database will update according to the change in those XML.
Solution:
You MUST do Snapshot after Subscription/Update Subscription. without Snapshot you CANNOT do Syncronization/Pull/Push/
Suggestion:
If you dont want to spent a lot of time to see snapshot working, then you can try to :
1. EMPTYING the database in both Sub and Pub servers BEFORE SNAPSHOT and left it only with 5-10 row of data..i supposed you have a lot of constrain which is make you hard to empying data from full filled data..so let 5-10 row data left,
2. Then you can DO SNAPSHOT with very fast becouse only involve small ampount of data.
3. Then you can IMPORT the REST of data to one server with IMPORT COMMAND (depend on your DB Server software used)
4. Then make PULL/PUSH so both server will TRANSFER the data WHILE you already success do SNAPSHOT easily. of course it still take a lot time to transfer data.but at least the SYncronisation worked out.
Good Luck
Oki Sugama
Experience with Multimaster?
Thank you for the answer, Oki San.
Sorry I'm late. I'm working on the database preparation for the replication in DBR. My problem is with about 50.000 pictures in the database, so the "replication" file is almost 15GB big. Upload link is just 256kb wide and the initial loading must be quite long. After I determine the loading table order, I'll leave a couple of days for the snapshot (initial loading).
What is it your experience with the multimaster replication? How frequently does perform the data exchange between servers? I need that this works in the timefarme of one hour with all servers. Is it possibly with DBReplicator?
Kindly regards
Djordje