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This article introduces the relevant knowledge of "how to use snapshot operation interface functions in PostgreSQL". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Snapshot operation interface function

1. Create a snapshot. When the BLOCK changes, the BLOCK (old version) before the change is written to the * .snapmap.SNAP _ ID file file. Until the snapshot is deleted.

/ * Create new snapshot. Starting from this moment Postgres will store original copies of all updated pages. * Them will be stored in shanpshot file (* .snap.SNAP _ ID and addressed through * .snapmap.SNAP_ID file) until * snapshot is deleted by sfs_remove_snapshot function or new snapshot is created. * / extern SnapshotId sfs_make_snapshot (void)

2. Delete snapshot.

/ * * Remove snapshot with all it's files * / extern void sfs_remove_snapshot (SnapshotId sid)

3. Restore the database to the specified snapshot.

/ * Reset database state to the paritcular snapshot. * It will be not possible any more to recover to any of more recent snashots or to the most recent database state. * / extern void sfs_recover_to_snapshot (SnapshotId sid)

4. View a past state of the database. (it's not going back to what it used to be)

/ * Temporary switch instance to the particular snashot. It will be possible to return back to the most recent database state or to switch to any other snapshot * / extern void sfs_switch_to_snapshot (SnapshotId sid)

5. Just switch the current BACKEND PID to the state of a past SNAPSHOT ID in the database, instead of switching all BACKEND to a state in the past.

/ * Set snapshot for backend, unlike sfs_switch_to_snapshot function, it switchces snapshot for the current backend and not for all server instance. * / extern void sfs_set_backend_snapshot (SnapshotId sid)

These interfaces are very similar to the SNAPSHOT function of ZFS.

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