You can create a publication that only downloads data to remote databases, and never uploads data. Download-only publications do not use a transaction log on the client.
There are two ways to specify that only a download (and not an upload) should occur:
Download-only synchronization Use the dbmlsync options -e DownloadOnly or -ds.
Download-only publication Create the publication with the FOR DOWNLOAD ONLY keyword.
The two approaches are quite different:
| Download-only synchronizations | Download-only publications |
|---|---|
| If the download attempts to change rows that have been modified on the remote database and not yet uploaded, the download fails. | The download can overwrite rows that have been modified on the remote database and not yet uploaded. |
| Uses a normal publication that can be uploaded and/or downloaded. Download-only synchronization is specified using dbmlsync command line options or extended options. | Uses a download-only publication. All synchronizations on these publications are download-only. You cannot alter a normal publication to make it download-only. |
| Requires a log file. | Does not require a log file. |
| The log file is not truncated when these subscriptions are not uploaded for a long time, and can consume significant amounts of storage. | If there is a log file, the synchronization does not affect the synchronization truncation point. This means that the log file can still be truncated even if the publication is not synchronized for a long time. Download-only publications do not affect log file truncation. |
| You need to do an upload occasionally to reduce the amount of log that is scanned by the download-only synchronization. Otherwise, the download-only synchronization takes an increasingly long time to complete. | There is no need to ever do an upload. |
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