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SYSTEM CATALOG · 系统目录

pg_am

PostgreSQL 官方文档 ↗源码定义 ↗

The catalog pg_am stores information about relation access methods. There is one row for each access method supported by the system. Currently, only tables and indexes have access methods. The requirements for table and index access methods are discussed in detail in Chapter 62 and Chapter 63 respectively.

首次收录 PG 9.0最近收录 PG 19当前字段 4
9.09.19.29.39.49.59.610111213141516171819β3

已与 PostgreSQL 18.6 实例逐字段核对 · 原始实测记录 ↗

字段结构 PostgreSQL 18

pg_am
字段 / COLUMN类型 / TYPE说明 / DESCRIPTION
oid oidNOT NULL Row identifier
amname nameNOT NULL Name of the access method
amhandler regprocNOT NULL OID of a handler function that is responsible for supplying information about the access method引用：pg_proc.oid
amtype "char"NOT NULL文档原写法：char t = table (including materialized views), i = index.

标记“隐式列”的字段不包含在 SELECT * 中；部分早期统计视图由同版本源码补全，额外来源会显示在字段说明中。

通用系统列 6

PostgreSQL 提供的系统属性，通常不在 SELECT * 中展开。单独保留，不与普通字段混算。

字段类型attnum
tableoidoid-6
cmaxcid-5
xmaxxid-4
cmincid-3
xminxid-2
ctidtid-1

字段演化矩阵

悬停查看字段类型
存在新增 / 类型或属性变化移除
字段 / COLUMN9.09.19.29.39.49.59.610111213141516171819
oid
amname
amstrategies − – – – – – – – – – –
amsupport − – – – – – – – – – –
amcanorder − – – – – – – – – – –
amcanbackward − – – – – – – – – – –
amcanunique − – – – – – – – – – –
amcanmulticol − – – – – – – – – – –
amoptionalkey − – – – – – – – – – –
amindexnulls − – – – – – – – – – – – – – – –
amsearchnulls − – – – – – – – – – –
amstorage − – – – – – – – – – –
amclusterable − – – – – – – – – – –
amkeytype − – – – – – – – – – –
aminsert − – – – – – – – – – –
ambeginscan − – – – – – – – – – –
amgettuple − – – – – – – – – – –
amgetbitmap − – – – – – – – – – –
amrescan − – – – – – – – – – –
amendscan − – – – – – – – – – –
ammarkpos − – – – – – – – – – –
amrestrpos − – – – – – – – – – –
ambuild − – – – – – – – – – –
ambulkdelete − – – – – – – – – – –
amvacuumcleanup − – – – – – – – – – –
amcostestimate − – – – – – – – – – –
amoptions − – – – – – – – – – –
amcanorderbyop – − – – – – – – – – – –
ampredlocks – − – – – – – – – – – –
ambuildempty – − – – – – – – – – – –
amsearcharray – – − – – – – – – – – – –
amcanreturn – – − – – – – – – – – – –
amhandler – – – – – –
amtype – – – – – –

9.0 是收录基线；基线中已存在的字段不标记为新增。矩阵按字段名称对齐，重命名显示为旧字段移除与新字段新增。

演化时间线

相邻大版本的变化

PostgreSQL 18 ← 17

目录说明更新

PostgreSQL 17 ← 16

目录说明更新

PostgreSQL 15 ← 14

目录说明更新

PostgreSQL 14 ← 13

目录说明更新

PostgreSQL 12 ← 11

~ oid: 隐式列 → 常规列2 处字段说明更新目录说明更新

PostgreSQL 11 ← 10

目录说明更新

PostgreSQL 10 ← 9.6

目录说明更新

PostgreSQL 9.6 ← 9.5

+ amhandler+ amtype− amstrategies− amsupport− amcanorder− amcanorderbyop− amcanbackward− amcanunique− amcanmulticol− amoptionalkey− amsearcharray− amsearchnulls− amstorage− amclusterable− ampredlocks− amkeytype− aminsert− ambeginscan− amgettuple− amgetbitmap− amrescan− amendscan− ammarkpos− amrestrpos− ambuild− ambuildempty− ambulkdelete− amvacuumcleanup− amcanreturn− amcostestimate− amoptions目录说明更新

PostgreSQL 9.5 ← 9.4

1 处字段说明更新目录说明更新

PostgreSQL 9.4 ← 9.3

目录说明更新

PostgreSQL 9.3 ← 9.2

1 处字段说明更新目录说明更新

PostgreSQL 9.2 ← 9.1

+ amsearcharray+ amcanreturn

PostgreSQL 9.1 ← 9.0

+ amcanorderbyop+ ampredlocks+ ambuildempty− amindexnulls4 处字段说明更新目录说明更新

比较任意两个版本

选择两个版本，查看字段的新增、移除与类型变化。交互比较需要 JavaScript；演化时间线可直接阅读。