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This section provides three replication scheme examples, including samples of worksheet entries and corresponding diagrams. These examples are based on the 'Round the Earth Publishing (R.E.P.) scenario used in this chapter and in the chapter "Understanding Ingres Replicator." In these examples, the Company is not using horizontal partitioning.
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The Company's main CDDS (CDDS 0) is shared by its offices in New York City, San Francisco, Dallas, London, and Hong Kong. New York, London, and Hong Kong are full peers in this CDDS. San Francisco is a protected read-only target, and Dallas is an unprotected read-only target. The following table illustrates the database information on the CDDS Worksheet for this CDDS:
Database Number/Name |
Target Type |
Server Number |
|---|---|---|
10 nyc::hq |
1 (full peer) |
1 |
11 sfo::west |
2 (protected read-only) |
4 |
12 dal::central |
3 (unprotected read-only) |
4 |
20 lon::europe |
1 (full peer) |
2 |
30 hkg::asia |
1 (full peer) |
3 |
New York acts as the U.S. hub and distributes data to San Francisco, Dallas, and London. London acts as the international hub and sends data to New York and Hong Kong. San Francisco is the U.S. alternate site and has a redundant path from Hong Kong.
The Company's CDDS Diagram for CDDS 0 looks like this:
The Company's Propagation Path entries on the CDDS Worksheet for CDDS 0 are listed in the following table:
Originator DB |
Local DB |
Target DB |
Comment |
|---|---|---|---|
10 |
10 |
11 |
NYC to SFO |
10 |
10 |
12 |
NYC to DAL |
10 |
10 |
20 |
NYC to LON |
10 |
20 |
30 |
NYC to HKG through LON |
10 |
30 |
11 |
NYC to SFO through LON and HKG |
20 |
20 |
10 |
LON to NYC |
20 |
20 |
30 |
LON to HKG |
20 |
30 |
11 |
LON to SFO through HKG |
20 |
10 |
12 |
LON to DAL through NYC |
20 |
10 |
11 |
LON to SFO through NYC |
30 |
30 |
11 |
HKG to SFO |
30 |
30 |
20 |
HKG to LON |
30 |
20 |
10 |
HKG to NYC through LON |
30 |
10 |
11 |
HKG to SFO through LON and NYC |
30 |
10 |
12 |
HKG to DAL through LON and NYC |
Because the San Francisco database has a redundant path, it has collisions when the same transaction arrives from both New York and Hong Kong. The Company handles this situation by using the collision mode BenignResolution, which resolves collisions that have the same transaction ID.
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The Company's London and Hong Kong offices share an international sales CDDS (CDDS 2), with each of them acting as full peers. The database information on the CDDS Worksheet for this CDDS is as follows:
Database No./Name Target Type Server Number
20 lon::europe 1 (full peer) 22
30 hkg::asia 1 (full peer) 23
The Replicator Server numbers assigned to each database are different than the Replicator Server numbers for CDDS 0. Therefore, the replications from CDDS 2 do not add traffic to the CDDS 0 Replicator Servers.
The Company's CDDS diagram for CDDS 0 looks like this:
The Company's Propagation Path entries on the CDDS Worksheet for CDDS 0 are as follows:
Originator DB Local DB Target DB Comment
30 30 20 HKG to LON
20 20 30 LONG to HKG
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The Company decides that it wants to move the transactions for the inventory CDDS (CDDS 1) off the Replicator Servers that also handle transactions for the main CDDS (CDDS 0). The Company changes the Replicator Server assignments for CDDS 1.
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The new database information for the CDDS Worksheet for CDDS 1 is listed in the following table:
Database Number/Name |
Target Type |
Server Number |
|---|---|---|
10 nyc::hq |
1 (full peer) |
11 |
11 sfo::west |
1 (full peer) |
14 |
20 lon::europe |
1 (full peer) |
12 |
The other sections of the CDDS Worksheet for CDDS 1 remain the same.
The Company now has different Replicator Servers for almost every target and CDDS.
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The Company must assign the Replicator Server numbers for CDDS 0 according to the following table:
Server Number |
Database |
|---|---|
1 |
nyc::hq |
2 |
lon::europe |
3 |
hkg::asia |
4 |
both sfo::west and dal::central |
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The Company must assign the Replicator Server numbers for CDDS 1 according to the following table.
Server Number |
Database |
|---|---|
11 |
nyc::hq |
12 |
lon::europe |
14 |
sfo::west |
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The Company must assign the Replicator Server numbers for CDDS 2 according to the following table.
Server Number |
Database |
|---|---|
22 |
lon::europe |
23 |
hkg::asia |