Using DataExchange

A Guide to Using DataExchange in Daily Operations

The following topics provide in-depth information for using DataExchange on a daily basis. They include discussions about fundamental concepts, as well as procedural information for dealing with some of the common scenarios you may encounter during replication.

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Activation

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Deactivation

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Adding Dynamic Tables to an Activated Database

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Changing a Table Structure in an Activated Database

Activation

Activation is the process of creating a new database for replication, or enabling an existing one, and defining it as belonging to a site within a replication network so that it can replicate. Because activation associates a database with a site, activating a database and activating a site mean the same thing.

The Deployment Wizard and dxdeploy command-line utility both activate replication databases automatically as part of deployment. The dxact command-line utility provides a manual method of activation as well as the flexibility to specify options such as preprocessing of starter data. For this discussion, we use dxact to activate the sample database, but first it’s important to first understand a few concepts in the activation process:

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Activation and Data Source Names

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Activating First and Partner Sites

Activation and Data Source Names

When you activate a database, DataExchange creates an internal system data source name (DSN) to point to the activated copy. In addition, DataExchange installation creates a database called PSQL DataExchange Database Network Analysis (PDDNA), which is the internal replication database. This database appears in PSQL Explorer with the DNA icon in its Replication node.

Caution Do not alter or otherwise directly attempt to use the internal DNA database (PDDNA). Doing so can corrupt the DataExchange installation.

Activating First and Partner Sites

The First Site special because it contains information needed to manage the replication network. The First Site must be activated before any of the Partner Sites so that they each can obtain copies of the information. Once the First Site is activated, you may activate your Partner Sites in any order. You can use the Deployment Wizard, dxdeploy.exe or dxact.exe on each Partner Site machine to activate it.

Tip The replication engine must be running to activate a database.

If possible, each Partner Site machine should have a network connection to allow it to communicate with the First Site so that the initial replication session can start immediately. This is not mandatory, however. You can perform the initial replication at a later time if you prefer. In the Data Synchronization edition, a Partner Site cannot replicate with other Partner Sites until it performs an initial replication with the First Site.

Once you’ve successfully performed activation, PSQL Control Center displays the database as activated, with the Replication node icon showing a letter A.

Once the initial replication has succeeded, the newly installed site is fully aware of all administrative data in that network, including all replication schedules.

For more information

Specific information about using each of the DataExchange deployment utilities is available in Using the DataExchange Utilities and Services. The following table provides specific reference information.

Activation Method	For more information...
Deployment Wizard (Dpwizard.exe)	See dpwizard
Dxdeploy.exe	See dxdeploy
Dxact.exe	See dxact

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To activate using dxact.exe

On the site machine you want to activate, open a command prompt window to start dxact.exe.

At the prompt, type a command similar to the following:

dxact demodata /FI

This example activates the demodata database on the First Site using the dxact.exe utility. By default, messages from dxact.exe are written to the dxact.log file, not to the screen. To view the messages on the screen while dxact.exe runs, use the /LOGFILE= option. To do so, you would enter a command similar to the following:

dxact demodata /Logfile= /FI

The /FI option specifies you are activating the First Site, but you should always run dxact.exe from the site you want to activate – remote activations are not available in DataExchange. For the complete list of dxact.exe options available, see dxact.

Now that we’ve covered the basics of activation, the next topics are deactivation and reactivation.

Deactivation

Deactivation is the disabling of an activated database in a replication network. Deactivation uses the dxdeact utility as explained in Using the DataExchange Utilities and Services.

If you deactivate a database on the First Site, PSQL Control Center displays the First Site database as a design template, since it was used to design the database for the replication network. When the First Site is deactivated, the Replication node icon displays a letter T.

When a Partner Site is deactivated, in PSQL Control Center on that site the Replication node icon for the database no longer displays a letter A for activation.

Other sites do not detect a deactivated site until replication occurs, which fails for the deactivated site. This is normal and generates an error message similar to the following in the dre.log file:

E 019f 0301-15:46:25 Partner site Partner_Site_2 (site number: 00LFLU) has been removed from the replication network - it cannot replicate with any other site.

After the failed replication, the error no longer occurs because all sites in the replication network have detected the deactivated site.

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To deactivate using dxdeact.exe

On the site machine you want to deactivate, open a command prompt window to start dxdeact.

At the prompt, type a command similar to the following:

dxdeact demodata

This example deactivates the demodata database using the dxdeact utility. By default, messages from dxdeact are written to the dxdeact.log file, not to the screen. To view the messages on the screen while dxdeact runs, use the /LOGFILE= option just as you did earlier with dxact.exe. It’s helpful to note that all the DataExchange Utilities provide the /LOGFILE= option to control logging output. For the complete list of dxdeact.exe options available, see dxdeact.

Reactivation

Reactivation is the reenabling of a deactivated site for replication. A database must be deactivated before it can be reactivated. Reactivation is, in essence, the same as activation in that you use the dxact utility in the same manner as you did when you activated.

If you deactivate a First Site, you must perform a manual replication if you reactivate the First Site. After you reactivate the First Site, you must manually initiate a replication session from each Partner Site to the First Site. The replication sessions ensure that all available sites appear on the Initiate Replication dialog.

Note Manually initiating a replication session is not required if you deactivate/reactivate a Partner Site. It applies only to a First Site.

Adding Dynamic Tables to an Activated Database

You applications may add tables to a PSQL database that did not exist at the time database replication was set up in DataExchange. DataExchange provides a way to include these new tables in – or exclude certain tables from – the set of replicated tables for an activated database. Only table files should be included because only tables may be replicated. Any type of file may be excluded, but whether or not you exclude them, files other than tables are not replicated.

The new tables are identified by a pattern-matching algorithm, which uses glob-style patterns in both regular and dir expressions. You specify which file patterns you want the algorithm to use. Blank by default, the patterns are the only input required from you. DataExchange does the rest automatically.

DataExchange first compares file names for the include pattern then compares file names against the exclude pattern. Only files whose names pass both comparisons are included. For example, suppose you specify c:\mydata\*.d?? as an include pattern. If you specify an exclude pattern of c:\mydata\*.ddf, then all files in c:\mydata will be included except for ones with a file extension of “ddf.”