pg_resetxlog 1 Application pg_resetxlog reset write-ahead log file and optionally the pg_control file pg_resetxlog -f -n -x xid -l fileid,seg datadir pg_resetxlog clears the write-ahead log file and optionally the pg_control file. This function is sometimes needed if these files have become corrupted. It should be used only as a last resort, when the server will not start due to such corruption. After running this command, it should be possible to start the server, but bear in mind that the database may contain inconsistent data due to partially-committed transactions. You should immediately dump your data, run initdb, and reload. After reload, check for inconsistencies and repair as needed. This utility can only be run by the user who installed the server, because it requires read/write access to the datadir. For safety reasons, you must specify the data directory on the command line. pg_resetxlog does not use the environment variable PGDATA. If pg_resetxlog complains that it cannot determine valid data for pg_control, you can force it to proceed anyway by specifying the -f (force) switch. In this case plausible values will be substituted for the missing data. If -f is used then the recovered database must be treated with even more suspicion than usual --- an immediate dump and reload is imperative. Do not execute any data-modifying operations in the database before you dump, as any such action is likely to make the corruption worse. The -n (no operation) switch instructs pg_resetxlog to print the values reconstructed from pg_control and then exit without modifying anything. This is mainly a debugging tool, but may be useful as a sanity check before allowing pg_resetxlog to proceed for real. The -x and -l switches are intended for use by pg_upgrade. In most cases they should not be used in manual recovery operations. This command must not be used when the postmaster is running. pg_resetxlog will refuse to start up if it finds a postmaster lock file in the datadir. If the postmaster crashed then a lock file may have been left behind; in that case you can remove the lock file to allow pg_resetxlog to run. But before you do so, make doubly certain that there is no postmaster nor any backend server process still alive.