diff --git a/doc/src/sgml/backup-manifest.sgml b/doc/src/sgml/backup-manifest.sgml new file mode 100644 index 0000000000..376aff0d6d --- /dev/null +++ b/doc/src/sgml/backup-manifest.sgml @@ -0,0 +1,212 @@ + + + + Backup Manifest Format + + + The backup manifest generated by is + primarily intended to permit the backup to be verified using + . However, it is + also possible for other tools to read the backup manifest file and use + the information contained therein for their own purposes. To that end, + this chapter describes the format of the backup manifest file. + + + + A backup manifest is a JSON document encoded as UTF-8. (Although in + general JSON documents are required to be Unicode, PostgreSQL permits + the json and jsonb data types to be used with any + supported server encoding. There is no similar exception for backup + manifests.) The JSON document is always an object; the keys that are present + in this object are described in the next section. + + + + Backup Manifest Toplevel Object + + + The backup manifest JSON document contains the following keys. + + + + + PostgreSQL-Backup-Manifest-Version + + + The associated value is always the integer 1. + + + + + + Files + + + The associated value is always a list of objects, each describing one + file that is present in the backup. No entries are present in this + list for the WAL files that are needed in order to use the backup, + or for the backup manifest itself. The structure of each object in the + list is described in . + + + + + + WAL-Ranges + + + The associated value is always a list of objects, each describing a + range of WAL records that must be readable from a particular timeline + in order to make use of the backup. The structure of these objects is + further described in . + + + + + + Manifest-Checksum + + + This key is always present on the last line of the backup manifest file. + The associated value is a SHA256 checksum of all the preceding lines. + We use a fixed checksum method here to make it possible for clients + to do incremental parsing of the manifest. While a SHA256 checksum + is significantly more expensive than a CRC32C checksum, the manifest + should normally be small enough that the extra computation won't matter + very much. + + + + + + + + Backup Manifest File Object + + + The object which describes a single file contains either a + Path key or an Encoded-Path key. + Normally, the Path key will be present. The + associated string value is the path of the file relative to the root + of the backup directory. Files located in a user-defined tablespace + will have paths whose first two components are pg_tblspc and the OID + of the tablespace. If the path is not a string that is legal in UTF-8, + or if the user requests that encoded paths be used for all files, then + the Encoded-Path key will be present instead. This + stores the same data, but it is encoded as a string of hexadecimal + digits. Each pair of hexadecimal digits in the string represents a + single octet. + + + + The following two keys are always present: + + + + + Size + + + The expected size of this file, as an integer. + + + + + + Last-Modified + + + The last modification time of the file as reported by the server at + the time of the backup. Unlike the other fields stored in the backup, + this field is not used by . + It is included only for informational purposes. + + + + + + + If the backup was taken with file checksums enabled, the following + keys will be present: + + + + + Checksum-Algorithm + + + The checksum algorithm used to compute a checksum for this file. + Currently, this will be the same for every file in the backup + manifest, but this may change in future releases. At present, the + supported checksum algorithms are CRC32C, + SHA224, + SHA256, + SHA384, and + SHA512. + + + + + + Checksum + + + The checksum computed for this file, stored as a series of + hexadecimal characters, two for each byte of the checksum. + + + + + + + + Backup Manifest WAL Range Object + + + The object which describes a WAL range always has three keys: + + + + + Timeline + + + The timeline for this range of WAL records, as an integer. + + + + + + Start-LSN + + + The LSN at which replay must begin on the indicated timeline in order to + make use of this backup. The LSN is stored in the format normally used + by PostgreSQL; that is, it is a string + consisting of two strings of hexadecimal characters, each with a length + of between 1 and 8, separated by a slash. + + + + + + End-LSN + + + The earliest LSN at which replay on the indicated timeline may end when + making use of this backup. This is stored in the same format as + Start-LSN. + + + + + + + Ordinarily, there will be only a single WAL range. However, if a backup is + taken from a standby which switches timelines during the backup due to an + upstream promotion, it is possible for multiple ranges to be present, each + with a different timeline. There will never be multiple WAL ranges present + for the same timeline. + + + diff --git a/doc/src/sgml/filelist.sgml b/doc/src/sgml/filelist.sgml index cf21ef857e..68179f71cd 100644 --- a/doc/src/sgml/filelist.sgml +++ b/doc/src/sgml/filelist.sgml @@ -102,6 +102,7 @@ + diff --git a/doc/src/sgml/postgres.sgml b/doc/src/sgml/postgres.sgml index f4a3c7e5e7..c41ce9499b 100644 --- a/doc/src/sgml/postgres.sgml +++ b/doc/src/sgml/postgres.sgml @@ -268,6 +268,7 @@ break is not needed in a wider output rendering. &storage; &bki; &planstats; + &backup-manifest;