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pg_lsn

PostgreSQL Log Sequence Number

Reading PostgreSQL 18.6.

PG10–20 core source inventory. Casts and operator classes show explicitly declared relationships; absent rows do not rule out coercions or indexing through other mechanisms.

Definition

PostgreSQL Log Sequence Number

pg_lsn

Catalog name: pg_catalog.pg_lsn
Type OID: 3220
Type kind: Base type
Declared length: 8 bytes
Storage strategy: plain
Input function: pg_lsn_in
Output function: pg_lsn_out

English manual

Read the complete manual section

Read the source definition

8.20. `pg_lsn` Type

The pg_lsn data type can be used to store LSN (Log Sequence Number) data which is a pointer to a location in the WAL. This type is a representation of XLogRecPtr and an internal system type of PostgreSQL.

Internally, an LSN is a 64-bit integer, representing a byte position in the write-ahead log stream. It is printed as two hexadecimal numbers of up to 8 digits each, separated by a slash; for example, 16/B374D848. The pg_lsn type supports the standard comparison operators, like = and >. Two LSNs can be subtracted using the - operator; the result is the number of bytes separating those write-ahead log locations. Also the number of bytes can be added into and subtracted from LSN using the +(pg_lsn,numeric) and -(pg_lsn,numeric) operators, respectively. Note that the calculated LSN should be in the range of pg_lsn type, i.e., between 0/0 and FFFFFFFF/FFFFFFFF.

Catalog attributes

Source bootstrap values for this build. See pg_type for field meanings. Header defaults are included; build-dependent constants remain symbolic. This is not a live-server measurement.

oid: 3220
descr: PostgreSQL LSN
typacl: _null_
typlen: 8
typelem: 0
typname: pg_lsn
typsend: pg_lsn_send
typtype: b
typalign: d
typarray: 0
typbyval: FLOAT8PASSBYVAL
typdelim: ','
typinput: pg_lsn_in
typmodin: -
typndims: 0
typowner: POSTGRES
typrelid: 0
typmodout: -
typoutput: pg_lsn_out
typtypmod: -1
typanalyze: -
typdefault: _null_
typnotnull: f
typreceive: pg_lsn_recv
typstorage: p
typbasetype: 0
typcategory: U
typcollation: 0
typisdefined: t
typnamespace: pg_catalog
typsubscript: -
typdefaultbin: _null_
array_type_oid: 3221
typispreferred: f
array_type_name: _pg_lsn

Operator overloads 10

Each operand signature is a separate overload. Catalog implementation functions and result types belong to the same source build.

Operator	Left operand	Right operand	Result	Meaning	Implementation
`=`	`pg_lsn`	`pg_lsn`	`bool`	`equal`	`pg_lsn_eq`
`<>`	`pg_lsn`	`pg_lsn`	`bool`	`not equal`	`pg_lsn_ne`
`<`	`pg_lsn`	`pg_lsn`	`bool`	`less than`	`pg_lsn_lt`
`>`	`pg_lsn`	`pg_lsn`	`bool`	`greater than`	`pg_lsn_gt`
`<=`	`pg_lsn`	`pg_lsn`	`bool`	`less than or equal`	`pg_lsn_le`
`>=`	`pg_lsn`	`pg_lsn`	`bool`	`greater than or equal`	`pg_lsn_ge`
`-`	`pg_lsn`	`pg_lsn`	`numeric`	`minus`	`pg_lsn_mi`
`+`	`pg_lsn`	`numeric`	`pg_lsn`	`add`	`pg_lsn_pli`
`+`	`numeric`	`pg_lsn`	`pg_lsn`	`add`	`numeric_pl_pg_lsn`
`-`	`pg_lsn`	`numeric`	`pg_lsn`	`subtract`	`pg_lsn_mii`

Operator classes 5

Operator classes whose declared input type matches this type. Polymorphic classes, casts and expression indexes can provide additional index paths; this list is not an exhaustive yes/no index-support test.

Class	Index method	Input type	Family	Default	Storage type
`pg_lsn_ops`	`btree`	`pg_lsn`	`btree/pg_lsn_ops`	`Yes`	`Same as input`
`pg_lsn_ops`	`hash`	`pg_lsn`	`hash/pg_lsn_ops`	`Yes`	`Same as input`
`pg_lsn_minmax_ops`	`brin`	`pg_lsn`	`brin/pg_lsn_minmax_ops`	`Yes`	`pg_lsn`
`pg_lsn_minmax_multi_ops`	`brin`	`pg_lsn`	`brin/pg_lsn_minmax_multi_ops`	`No`	`pg_lsn`
`pg_lsn_bloom_ops`	`brin`	`pg_lsn`	`brin/pg_lsn_bloom_ops`	`No`	`pg_lsn`

Version comparison

PostgreSQL 17.11 → 18.6. Source build identifiers and prose are excluded from attribute changes.

No catalog or structured attribute changes between these samples.

Documentation and source

Build: 18.6 · https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
Fingerprint: 555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f

Related entries

All Data Types · Download this version as JSON · The first recorded sample does not establish when a type was introduced.