The
dgraph_input/updates directory contains partial
updates data that have yet to be processed by the MDEX Engine. The MDEX Engine
checks this directory for update files, when the
--updatedir flag is specified for the Dgraph.
After a partial update completes successfully, the index is
updated with the changes from that update. The update files are no longer
needed by the MDEX Engine and are automatically removed from the
dgraph_input/updates directory.
The default MDEX Engine behavior includes checking the
dgraph_input/updates on restart. When the Dgraph
starts, it checks for the update files in the
dgraph_input/updates directory, in case this
directory contains any of them. Under normal conditions, this directory should
be empty since the MDEX Engine deletes update files after applying them.
Checking the
dgraph_input/updates directory is also useful if
partial updates become available immediately after a baseline update. For
example, consider a case when a baseline update runs, followed by a partial
update that captures data that became available while the baseline was running.
If you restart the Dgraph immediately after this partial update, the MDEX
Engine reads these most recent updates after it restarts and then proceeds to
answer queries.
If the Dgraph server crashes in the middle of a partial update, the
files from that update are not deleted from
dgraph_input/updates. When the MDEX Engine is
restarted, it retains the index state it had before this partial update was
attempted. After a restart, the MDEX Engine checks the contents of
dgraph_input/updates for the presence of last
partial update files that were not applied and applies them.
Oracle recommends that you back up this directory to ensure that you can recover after a disk failure.
