PG数据库如何通过函数查看表和索引的DDL定义

一 通过自定义函数查看表的ddl定义

新建函数tabledef

CREATE OR REPLACE FUNCTION tabledef(oid) RETURNS text

LANGUAGE sql STRICT AS $$

WITH attrdef AS (

    SELECT

        n.nspname,

        c.relname,

        pg_catalog.array_to_string(c.reloptions || array(select 'toast.' || x from pg_catalog.unnest(tc.reloptions) x), ', ') as relopts,

        c.relpersistence,

        a.attnum,

        a.attname,

        pg_catalog.format_type(a.atttypid, a.atttypmod) as atttype,

        (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid, true) for 128) FROM pg_catalog.pg_attrdef d

            WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef) as attdefault,

        a.attnotnull,

        (SELECT c.collname FROM pg_catalog.pg_collation c, pg_catalog.pg_type t

            WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) as attcollation,

        a.attidentity,

        a.attgenerated

    FROM pg_catalog.pg_attribute a

    JOIN pg_catalog.pg_class c ON a.attrelid = c.oid

    JOIN pg_catalog.pg_namespace n ON c.relnamespace = n.oid

    LEFT JOIN pg_catalog.pg_class tc ON (c.reltoastrelid = tc.oid)

    WHERE a.attrelid = $1

        AND a.attnum > 0

        AND NOT a.attisdropped

    ORDER BY a.attnum

),

coldef AS (

    SELECT

        attrdef.nspname,

        attrdef.relname,

        attrdef.relopts,

        attrdef.relpersistence,

        pg_catalog.format(

            '%I %s%s%s%s%s',

            attrdef.attname,

            attrdef.atttype,

            case when attrdef.attcollation is null then '' else pg_catalog.format(' COLLATE %I', attrdef.attcollation) end,

            case when attrdef.attnotnull then ' NOT NULL' else '' end,

            case when attrdef.attdefault is null then ''

                else case when attrdef.attgenerated = 's' then pg_catalog.format(' GENERATED ALWAYS AS (%s) STORED', attrdef.attdefault)

                    when attrdef.attgenerated <> '' then ' GENERATED AS NOT_IMPLEMENTED'

                    else pg_catalog.format(' DEFAULT %s', attrdef.attdefault)

                end

            end,

            case when attrdef.attidentity<>'' then pg_catalog.format(' GENERATED %s AS IDENTITY',

                    case attrdef.attidentity when 'd' then 'BY DEF