{"Entry":{"collection":"type","key":"table_am_handler","name":"table_am_handler","aliases":[],"metadata":{"aliases":[],"category":"Pseudo-types","content_hash":"919b554fa4e949f19f26f5a64e42dd411b317a6d6d7e8c8d4832c75d65a13bcf","derived_content_hash":"7e417082336d318aac63c1f66767541a365031e35b88c9681969e95c8340e02a","imported_at":"2026-09-30T00:40:36.679202+08:00","name":"table_am_handler","name_zh":"","slug":"table_am_handler","summary":"A table access method handler is declared to return table_am_handler ."}},"Definition":{"Collection":"type","Key":"table_am_handler","SourceDatabase":"center","Version":"18","SourceTable":"data_type","SourceKey":"table_am_handler","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","Facts":{"aliases":[],"casts":[],"catalog":{"array_type_name":"","array_type_oid":"0","descr":"pseudo-type for the result of a table AM handler function","oid":"269","typacl":"_null_","typalign":"i","typanalyze":"-","typarray":"0","typbasetype":"0","typbyval":"t","typcategory":"P","typcollation":"0","typdefault":"_null_","typdefaultbin":"_null_","typdelim":"','","typelem":"0","typinput":"table_am_handler_in","typisdefined":"t","typispreferred":"f","typlen":"4","typmodin":"-","typmodout":"-","typname":"table_am_handler","typnamespace":"pg_catalog","typndims":"0","typnotnull":"f","typoutput":"table_am_handler_out","typowner":"POSTGRES","typreceive":"-","typrelid":"0","typsend":"-","typstorage":"p","typsubscript":"-","typtype":"p","typtypmod":"-1"},"comparison_data":{"aliases":[],"casts":[],"catalog":{"array_type_name":"","typacl":"_null_","typalign":"i","typanalyze":"-","typarray":"","typbasetype":"0","typbyval":"t","typcategory":"P","typcollation":"0","typdefault":"_null_","typdefaultbin":"_null_","typdelim":",","typelem":"0","typinput":"table_am_handler_in","typisdefined":"t","typispreferred":"f","typlen":"4","typmodin":"-","typmodout":"-","typname":"table_am_handler","typndims":"0","typnotnull":"f","typoutput":"table_am_handler_out","typreceive":"-","typrelid":"0","typsend":"-","typstorage":"p","typsubscript":"-","typtype":"p","typtypmod":"-1"},"facts":[{"label":"Catalog name","value":"pg_catalog.table_am_handler"},{"label":"Declared length","value":"4 bytes"},{"label":"Documented declaration","value":"table_am_handler"},{"label":"Input function","value":"table_am_handler_in"},{"label":"Output function","value":"table_am_handler_out"},{"label":"Storage strategy","value":"plain"},{"label":"Type OID","value":"269"},{"label":"Type kind","value":"Pseudo-type"}],"operator_classes":[],"operators":[],"ranges":[]},"comparison_hash":"4bcae3064ba320553ce8dbbcfc92158ec8c41910b421c18f2f5d2ff83d2c207c","coverage":"source inventory; exact declared input types for operator classes","description":["A table access method handler is declared to return table_am_handler ."],"description_zh":"表示表访问方法处理器被声明为返回 table_am_handler 。","description_zh_html":"\u003cp\u003e表示表访问方法处理器被声明为返回 table_am_handler 。\u003c/p\u003e\u003ch3\u003e同版本中文手册定义\u003c/h3\u003e\u003ctable\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd\u003e\u003ccode class=\"type\"\u003etable_am_handler\u003c/code\u003e\u003c/td\u003e\u003ctd\u003e表示表访问方法处理器被声明为返回 \u003ccode class=\"type\"\u003etable_am_handler\u003c/code\u003e。\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003cp\u003e\u003ca href=\"/zh/docs/18/datatype-pseudo.html\"\u003e查看完整中文手册与上下文\u003c/a\u003e。\u003c/p\u003e","facts":[{"label":"Catalog name","value":"pg_catalog.table_am_handler"},{"label":"Type OID","value":"269"},{"label":"Type kind","value":"Pseudo-type"},{"label":"Declared length","value":"4 bytes"},{"label":"Storage strategy","value":"plain"},{"label":"Input function","value":"table_am_handler_in"},{"label":"Output function","value":"table_am_handler_out"},{"label":"Documented declaration","value":"table_am_handler"},{"label":"Manual description","value":"A table access method handler is declared to return table_am_handler ."}],"facts_zh":[{"label":"目录名称","value":"pg_catalog.table_am_handler"},{"label":"类型 OID","value":"269"},{"label":"类型种类","value":"Pseudo-type"},{"label":"声明长度","value":"4 字节"},{"label":"存储策略","value":"plain"},{"label":"输入函数","value":"table_am_handler_in"},{"label":"输出函数","value":"table_am_handler_out"},{"label":"手册中的声明","value":"table_am_handler"},{"label":"手册说明","value":"表示表访问方法处理器被声明为返回 table_am_handler 。"}],"manual_documentation":"dedicated family chapter","manual_html":"\u003cdiv class=\"sect1\" id=\"DATATYPE-PSEUDO\"\u003e\n\u003cdiv class=\"titlepage\"\u003e\n\u003cdiv\u003e\n\u003cdiv\u003e\n\u003ch2 class=\"title\"\u003e8.21. Pseudo-Types \u003c/h2\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eThe \u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e type system contains a number of special-purpose entries that are collectively called \u003cem class=\"firstterm\"\u003epseudo-types\u003c/em\u003e. A pseudo-type cannot be used as a column data type, but it can be used to declare a function's argument or result type. Each of the available pseudo-types is useful in situations where a function's behavior does not correspond to simply taking or returning a value of a specific SQL data type. \u003ca class=\"xref\" href=\"/docs/18/datatype-pseudo.html#DATATYPE-PSEUDOTYPES-TABLE\" title=\"Table 8.27. Pseudo-Types\"\u003eTable 8.27\u003c/a\u003e lists the existing pseudo-types.\u003c/p\u003e\n\u003cdiv class=\"table\" id=\"DATATYPE-PSEUDOTYPES-TABLE\"\u003e\n\u003cp class=\"title\"\u003e\u003cstrong\u003eTable 8.27. Pseudo-Types\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv class=\"table-contents\"\u003e\n\u003ctable class=\"table\"\u003e\n\n\n\n\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eName\u003c/th\u003e\n\u003cth\u003eDescription\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eany\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any input data type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyelement\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any array data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanynonarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any non-array data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyenum\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any enum data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/datatype-enum.html\" title=\"8.7. Enumerated Types\"\u003eSection 8.7\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyrange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any range data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanymultirange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any multirange data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatible\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblearray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any array data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblenonarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any non-array data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblerange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any range data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblemultirange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any multirange data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003ecstring\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts or returns a null-terminated C string.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003einternal\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts or returns a server-internal data type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003elanguage_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA procedural language call handler is declared to return \u003ccode class=\"type\"\u003elanguage_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003efdw_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA foreign-data wrapper handler is declared to return \u003ccode class=\"type\"\u003efdw_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003etable_am_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA table access method handler is declared to return \u003ccode class=\"type\"\u003etable_am_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eindex_am_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eAn index access method handler is declared to return \u003ccode class=\"type\"\u003eindex_am_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003etsm_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA tablesample method handler is declared to return \u003ccode class=\"type\"\u003etsm_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003erecord\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a function taking or returning an unspecified row type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003etrigger\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA trigger function is declared to return \u003ccode class=\"type\"\u003etrigger.\u003c/code\u003e\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eevent_trigger\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eAn event trigger function is declared to return \u003ccode class=\"type\"\u003eevent_trigger.\u003c/code\u003e\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003epg_ddl_command\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a representation of DDL commands that is available to event triggers.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003evoid\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function returns no value.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eunknown\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a not-yet-resolved type, e.g., of an undecorated string literal.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\u003cbr class=\"table-break\"\u003e\n\u003cp\u003eFunctions coded in C (whether built-in or dynamically loaded) can be declared to accept or return any of these pseudo-types. It is up to the function author to ensure that the function will behave safely when a pseudo-type is used as an argument type.\u003c/p\u003e\n\u003cp\u003eFunctions coded in procedural languages can use pseudo-types only as allowed by their implementation languages. At present most procedural languages forbid use of a pseudo-type as an argument type, and allow only \u003ccode class=\"type\"\u003evoid\u003c/code\u003e and \u003ccode class=\"type\"\u003erecord\u003c/code\u003e as a result type (plus \u003ccode class=\"type\"\u003etrigger\u003c/code\u003e or \u003ccode class=\"type\"\u003eevent_trigger\u003c/code\u003e when the function is used as a trigger or event trigger). Some also support polymorphic functions using the polymorphic pseudo-types, which are shown above and discussed in detail in \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eThe \u003ccode class=\"type\"\u003einternal\u003c/code\u003e pseudo-type is used to declare functions that are meant only to be called internally by the database system, and not by direct invocation in an SQL query. If a function has at least one \u003ccode class=\"type\"\u003einternal\u003c/code\u003e-type argument then it cannot be called from SQL. 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A pseudo-type cannot be used as a column data type, but it can be used to declare a function\u0026#39;s argument or result type. Each of the available pseudo-types is useful in situations where a function\u0026#39;s behavior does not correspond to simply taking or returning a value of a specific SQL data type. \u003ca href=\"/docs/18/datatype-pseudo.html#DATATYPE-PSEUDOTYPES-TABLE\" rel=\"nofollow\"\u003eTable 8.27\u003c/a\u003e lists the existing pseudo-types.\u003c/p\u003e\n\u003cdiv id=\"DATATYPE-PSEUDOTYPES-TABLE\"\u003e\n\u003cp\u003e\u003cstrong\u003eTable 8.27. Pseudo-Types\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv\u003e\n\u003ctable\u003e\n\n\n\n\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eName\u003c/th\u003e\n\u003cth\u003eDescription\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eany\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any input data type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanyelement\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanyarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any array data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanynonarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any non-array data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanyenum\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any enum data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca href=\"/docs/18/datatype-enum.html\" rel=\"nofollow\"\u003eSection 8.7\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanyrange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any range data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca href=\"/docs/18/rangetypes.html\" rel=\"nofollow\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanymultirange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any multirange data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca href=\"/docs/18/rangetypes.html\" rel=\"nofollow\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanycompatible\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any data type, with automatic promotion of multiple arguments to a common data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanycompatiblearray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any array data type, with automatic promotion of multiple arguments to a common data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanycompatiblenonarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any non-array data type, with automatic promotion of multiple arguments to a common data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanycompatiblerange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any range data type, with automatic promotion of multiple arguments to a common data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca href=\"/docs/18/rangetypes.html\" rel=\"nofollow\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eanycompatiblemultirange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any multirange data type, with automatic promotion of multiple arguments to a common data type (see \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca href=\"/docs/18/rangetypes.html\" rel=\"nofollow\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003ecstring\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts or returns a null-terminated C string.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003einternal\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts or returns a server-internal data type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003elanguage_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA procedural language call handler is declared to return \u003ccode\u003elanguage_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003efdw_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA foreign-data wrapper handler is declared to return \u003ccode\u003efdw_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003etable_am_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA table access method handler is declared to return \u003ccode\u003etable_am_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eindex_am_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eAn index access method handler is declared to return \u003ccode\u003eindex_am_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003etsm_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA tablesample method handler is declared to return \u003ccode\u003etsm_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003erecord\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a function taking or returning an unspecified row type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003etrigger\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA trigger function is declared to return \u003ccode\u003etrigger.\u003c/code\u003e\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eevent_trigger\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eAn event trigger function is declared to return \u003ccode\u003eevent_trigger.\u003c/code\u003e\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003epg_ddl_command\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a representation of DDL commands that is available to event triggers.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003evoid\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function returns no value.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eunknown\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a not-yet-resolved type, e.g., of an undecorated string literal.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\u003cbr\u003e\n\u003cp\u003eFunctions coded in C (whether built-in or dynamically loaded) can be declared to accept or return any of these pseudo-types. It is up to the function author to ensure that the function will behave safely when a pseudo-type is used as an argument type.\u003c/p\u003e\n\u003cp\u003eFunctions coded in procedural languages can use pseudo-types only as allowed by their implementation languages. At present most procedural languages forbid use of a pseudo-type as an argument type, and allow only \u003ccode\u003evoid\u003c/code\u003e and \u003ccode\u003erecord\u003c/code\u003e as a result type (plus \u003ccode\u003etrigger\u003c/code\u003e or \u003ccode\u003eevent_trigger\u003c/code\u003e when the function is used as a trigger or event trigger). Some also support polymorphic functions using the polymorphic pseudo-types, which are shown above and discussed in detail in \u003ca href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" rel=\"nofollow\"\u003eSection 36.2.5\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eThe \u003ccode\u003einternal\u003c/code\u003e pseudo-type is used to declare functions that are meant only to be called internally by the database system, and not by direct invocation in an SQL query. If a function has at least one \u003ccode\u003einternal\u003c/code\u003e-type argument then it cannot be called from SQL. To preserve the type safety of this restriction it is important to follow this coding rule: do not create any function that is declared to return \u003ccode\u003einternal\u003c/code\u003e unless it has at least one \u003ccode\u003einternal\u003c/code\u003e argument.\u003c/p\u003e\n\u003c/div\u003e","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","ContentHash":"17ef3697eea12f5dabc6dcc94a761be91c61b6e5cd97b8c7e44a98a5c8a15879","Payload":{"description":["A table access method handler is declared to return table_am_handler ."],"manual_html":"\u003cdiv class=\"sect1\" id=\"DATATYPE-PSEUDO\"\u003e\n\u003cdiv class=\"titlepage\"\u003e\n\u003cdiv\u003e\n\u003cdiv\u003e\n\u003ch2 class=\"title\"\u003e8.21. Pseudo-Types \u003c/h2\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eThe \u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e type system contains a number of special-purpose entries that are collectively called \u003cem class=\"firstterm\"\u003epseudo-types\u003c/em\u003e. A pseudo-type cannot be used as a column data type, but it can be used to declare a function's argument or result type. Each of the available pseudo-types is useful in situations where a function's behavior does not correspond to simply taking or returning a value of a specific SQL data type. \u003ca class=\"xref\" href=\"/docs/18/datatype-pseudo.html#DATATYPE-PSEUDOTYPES-TABLE\" title=\"Table 8.27. Pseudo-Types\"\u003eTable 8.27\u003c/a\u003e lists the existing pseudo-types.\u003c/p\u003e\n\u003cdiv class=\"table\" id=\"DATATYPE-PSEUDOTYPES-TABLE\"\u003e\n\u003cp class=\"title\"\u003e\u003cstrong\u003eTable 8.27. Pseudo-Types\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv class=\"table-contents\"\u003e\n\u003ctable class=\"table\"\u003e\n\n\n\n\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eName\u003c/th\u003e\n\u003cth\u003eDescription\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eany\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any input data type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyelement\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any array data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanynonarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any non-array data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyenum\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any enum data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/datatype-enum.html\" title=\"8.7. Enumerated Types\"\u003eSection 8.7\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanyrange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any range data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanymultirange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any multirange data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatible\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblearray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any array data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblenonarray\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any non-array data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblerange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any range data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eanycompatiblemultirange\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts any multirange data type, with automatic promotion of multiple arguments to a common data type (see \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e and \u003ca class=\"xref\" href=\"/docs/18/rangetypes.html\" title=\"8.17. Range Types\"\u003eSection 8.17\u003c/a\u003e).\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003ecstring\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts or returns a null-terminated C string.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003einternal\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function accepts or returns a server-internal data type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003elanguage_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA procedural language call handler is declared to return \u003ccode class=\"type\"\u003elanguage_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003efdw_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA foreign-data wrapper handler is declared to return \u003ccode class=\"type\"\u003efdw_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003etable_am_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA table access method handler is declared to return \u003ccode class=\"type\"\u003etable_am_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eindex_am_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eAn index access method handler is declared to return \u003ccode class=\"type\"\u003eindex_am_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003etsm_handler\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA tablesample method handler is declared to return \u003ccode class=\"type\"\u003etsm_handler\u003c/code\u003e.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003erecord\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a function taking or returning an unspecified row type.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003etrigger\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA trigger function is declared to return \u003ccode class=\"type\"\u003etrigger.\u003c/code\u003e\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eevent_trigger\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eAn event trigger function is declared to return \u003ccode class=\"type\"\u003eevent_trigger.\u003c/code\u003e\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003epg_ddl_command\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a representation of DDL commands that is available to event triggers.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003evoid\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIndicates that a function returns no value.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode class=\"type\"\u003eunknown\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIdentifies a not-yet-resolved type, e.g., of an undecorated string literal.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\u003cbr class=\"table-break\"\u003e\n\u003cp\u003eFunctions coded in C (whether built-in or dynamically loaded) can be declared to accept or return any of these pseudo-types. It is up to the function author to ensure that the function will behave safely when a pseudo-type is used as an argument type.\u003c/p\u003e\n\u003cp\u003eFunctions coded in procedural languages can use pseudo-types only as allowed by their implementation languages. At present most procedural languages forbid use of a pseudo-type as an argument type, and allow only \u003ccode class=\"type\"\u003evoid\u003c/code\u003e and \u003ccode class=\"type\"\u003erecord\u003c/code\u003e as a result type (plus \u003ccode class=\"type\"\u003etrigger\u003c/code\u003e or \u003ccode class=\"type\"\u003eevent_trigger\u003c/code\u003e when the function is used as a trigger or event trigger). Some also support polymorphic functions using the polymorphic pseudo-types, which are shown above and discussed in detail in \u003ca class=\"xref\" href=\"/docs/18/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC\" title=\"36.2.5. Polymorphic Types\"\u003eSection 36.2.5\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eThe \u003ccode class=\"type\"\u003einternal\u003c/code\u003e pseudo-type is used to declare functions that are meant only to be called internally by the database system, and not by direct invocation in an SQL query. If a function has at least one \u003ccode class=\"type\"\u003einternal\u003c/code\u003e-type argument then it cannot be called from SQL. To preserve the type safety of this restriction it is important to follow this coding rule: do not create any function that is declared to return \u003ccode class=\"type\"\u003einternal\u003c/code\u003e unless it has at least one \u003ccode class=\"type\"\u003einternal\u003c/code\u003e argument.\u003c/p\u003e\n\u003c/div\u003e","related":[{"label":"pg_type catalog","url":"/wiki/catalog/pg_type/?v=18"},{"label":"pg_cast catalog","url":"/wiki/catalog/pg_cast/?v=18"},{"label":"pg_operator catalog","url":"/wiki/catalog/pg_operator/?v=18"},{"label":"pg_opclass catalog","url":"/wiki/catalog/pg_opclass/?v=18"},{"label":"Arrays","url":"/wiki/type/arrays/?v=18"}],"sections":[]}},"RequestedLocale":"en","Fallback":false,"Versions":["12","13","14","15","16","17","18","19","20"],"Locales":["en","zh-Hans"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}