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NSchema

Detecting drift

Drift is when the live database no longer matches what NSchema recorded — someone ran a manual ALTER, a hotfix added an index, or a column was dropped out of band. nschema drift reports it.

How it works

Section titled “How it works”

drift compares the recorded state against the live database and prints the difference as a diff (recorded → live):

  • an out-of-band addition appears as an add;
  • a manual drop appears as a remove.

It’s a pure observation — no transformers or policies run, so it never fails on a policy violation. It just tells you what’s different.

Terminal window
nschema drift

Gating a monitor on drift

Section titled “Gating a monitor on drift”

For a scheduled monitoring job, add --detailed-exitcode so the command’s exit status carries the answer — 0 for no drift, 2 for drift (errors stay 1):

Terminal window
nschema drift --detailed-exitcode

A simple cron/CI check:

Terminal window
if nschema drift --detailed-exitcode; then
  echo "In sync."
else
  case $? in
    2) echo "Drift detected!" ;;   # alert
    *) echo "drift check failed" ;;
  esac
fi

Reconciling drift

Section titled “Reconciling drift”

Once you’ve reviewed the drift, you have two ways to reconcile:

  • Adopt the live changes — capture the current database into the store with refresh, then update your .sql files to match so future plans stay clean.
  • Revert to your schema — run plan / apply to bring the database back in line with your declared desired state.