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pg_resetwal [-f] [-n] [option...] {[-D]datadir}

-f

Forcepg_resetwal to proceed even if it cannot determine valid data forpg_control, as explained above.

-n

The-n (no operation) option instructspg_resetwal to print the values reconstructed frompg_control and values about to be changed, and then exit without modifying anything. This is mainly a debugging tool, but can be useful as a sanity check before allowingpg_resetwal to proceed for real.

-V
--version

Display version information, then exit.

-?
--help

Show help, then exit.

-cxid,xid

Manually set the oldest and newest transaction IDs for which the commit time can be retrieved.

A safe value for the oldest transaction ID for which the commit time can be retrieved (first part) can be determined by looking for the numerically smallest file name in the directorypg_commit_ts under the data directory. Conversely, a safe value for the newest transaction ID for which the commit time can be retrieved (second part) can be determined by looking for the numerically greatest file name in the same directory. The file names are in hexadecimal.

-exid_epoch

Manually set the next transaction ID's epoch.

The transaction ID epoch is not actually stored anywhere in the database except in the field that is set bypg_resetwal, so any value will work so far as the database itself is concerned. You might need to adjust this value to ensure that replication systems such asSlony-I andSkytools work correctly — if so, an appropriate value should be obtainable from the state of the downstream replicated database.

-lwalfile

Manually set the WAL starting address.

The WAL starting address should be larger than any WAL segment file name currently existing in the directorypg_wal under the data directory. These names are also in hexadecimal and have three parts. The first part is the“timeline ID” and should usually be kept the same. For example, if00000001000000320000004A is the largest entry inpg_wal, use-l 00000001000000320000004B or higher.

Note

pg_resetwal itself looks at the files inpg_wal and chooses a default-l setting beyond the last existing file name. Therefore, manual adjustment of-l should only be needed if you are aware of WAL segment files that are not currently present inpg_wal, such as entries in an offline archive; or if the contents ofpg_wal have been lost entirely.

-mmxid,mxid

Manually set the next and oldest multitransaction ID.

A safe value for the next multitransaction ID (first part) can be determined by looking for the numerically largest file name in the directorypg_multixact/offsets under the data directory, adding one, and then multiplying by 65536 (0x10000). Conversely, a safe value for the oldest multitransaction ID (second part of-m) can be determined by looking for the numerically smallest file name in the same directory and multiplying by 65536. The file names are in hexadecimal, so the easiest way to do this is to specify the option value in hexadecimal and append four zeroes.

-ooid

Manually set the next OID.

There is no comparably easy way to determine a next OID that's beyond the largest one in the database, but fortunately it is not critical to get the next-OID setting right.

-Omxoff

Manually set the next multitransaction offset.

A safe value can be determined by looking for the numerically largest file name in the directorypg_multixact/members under the data directory, adding one, and then multiplying by 52352 (0xCC80). The file names are in hexadecimal. There is no simple recipe such as the ones for other options of appending zeroes.

-uxid

Manually set the oldest unfrozen transaction ID.

A safe value can be determined by looking for the numerically smallest file name in the directorypg_xact under the data directory and then multiplying by 1048576 (0x100000). Note that the file names are in hexadecimal. It is usually easiest to specify the option value in hexadecimal too. For example, if0007 is the smallest entry inpg_xact,-u 0x700000 will work (five trailing zeroes provide the proper multiplier).

-xxid

Manually set the next transaction ID.

A safe value can be determined by looking for the numerically largest file name in the directorypg_xact under the data directory, adding one, and then multiplying by 1048576 (0x100000). Note that the file names are in hexadecimal. It is usually easiest to specify the option value in hexadecimal too. For example, if0011 is the largest entry inpg_xact,-x 0x1200000 will work (five trailing zeroes provide the proper multiplier).