greenplum通过函数获取指定用户下的所有建表语句

函数实现

--获取数据库大小
CREATE OR REPLACE FUNCTION get_dbsize(dbname varchar)
RETURNS  VARCHAR AS
$FUNCTION$
DECLARE
	isExists 			varchar;
	dbsize 				varchar;
	databasename 		varchar;
BEGIN
	select datname into databasename from pg_database where lower(datname) = dbname;
	if databasename != '' THEN
		select pg_size_pretty(pg_database_size(lower(dbname))) into dbsize;
		return dbsize;
	else
		raise notice 'The database: % does not exists ! ',lower(dbname);
	end if;
END;
$FUNCTION$
LANGUAGE PLPGSQL;


--创建 get_table_structure 函数
CREATE PROCEDURAL LANGUAGE plpythonu;
create or replace function get_table_structure(tablename text)
    returns text
as $$
    try:
        table_name = tablename.lower().split('.')[1]
        talbe_schema=tablename.lower().split('.')[0]
    except (IndexError):
        return 'Please in put "tableschema.table_name"'
    get_table_oid="select oid,reloptions,relkind from pg_class where oid='%s'::regclass"%(tablename)
    try:
        rv_oid=plpy.execute(get_table_oid,5)
        if not rv_oid:
            return 'Did not find any relation named"'+tablename +'".'
    except (NameError):
        return 'Did not find any relation named"'+tablename +'".'
    table_oid=rv_oid[0]['oid']
    rv_reloptions=rv_oid[0]['reloptions']
    rv_relkind=rv_oid[0]['relkind']
    create_sql="";
    table_kind='table';
    if rv_relkind !='r' and rv_relkind !='v':
        plpy.error('%s is not table or view'%(tablename));
    elif rv_relkind=='v':
        get_view_def="select pg_get_viewdef(%s,'t') as viewdef;" % (table_oid)
        rv_viewdef=plpy.execute(get_view_def);
        create_sql='create view %s as \n' % (tablename)
        create_sql += rv_viewdef[0]['viewdef']+'\n';
        table_kind='view'
    else:
        get_columns="select a.attname,pg_catalog.format_type(a.atttypid,a.atttypmod),\
       (select substring(pg_catalog.pg_get_expr(d.adbin,d.adrelid) for 128) \
        from pg_catalog.pg_attrdef d where d.adrelid=a.attrelid and d.adnum=a.attnum and a.atthasdef) \
        as default,a.attnotnull as isnull from pg_catalog.pg_attribute \
        a where a.attrelid= %s and a.attnum >0 and not a.attisdropped order by a.attnum;" % (table_oid);
        rv_columns=plpy.execute(get_columns)
        
    
        get_table_distribution1="select attrnums from pg_catalog.gp_distribution_policy t where localoid = '" + table_oid + "' "
        rv_distribution1=plpy.execute(get_table_distribution1,500)
        rv_distribution2=''
        if rv_distribution1 and rv_distribution1[0]['attrnums']:
            get_table_distribution2="select attname from pg_attribute where attrelid='"+table_oid+"' and attnum in (" + str(rv_distribution1[0]['attrnums']).strip('{').strip('}').strip('[').strip(']')+")"
            rv_distribution2=plpy.execute(get_table_distribution2,500)
    
        create_sql='create table %s (\n' % (tablename)
        get_index="select pg_get_indexdef(indexrelid) as indexdef from pg_index where indrelid=%s" % (table_oid);
        rv_index=plpy.execute(get_index);

        
        get_parinfo1="select attname as columnname from pg_attribute where attnum =(select paratts[0] from pg_partition where parrelid=%s) and attrelid=%s;"%(table_oid,table_oid);
        get_parinfo2=""" select pp.parrelid,prl.parchildrelid,case when pp.parkind='h'::"char" then 'hash'::text when pp.parkind='r'::"char" then 'range'::text when pp.parkind='l'::"char" then 'list'::text else null::text end as partitiontype,pg_get_partition_rule_def(prl.oid,true) as partitionboundary from pg_partition pp,pg_partition_rule prl where pp.paristemplate=false and pp.parrelid = %s and prl.paroid = pp.oid order by prl.parname; """ % (table_oid)
        v_par_parent=plpy.execute(get_parinfo1);
        v_par_info=plpy.execute(get_parinfo2);
        max_column_len=10
        max_type_len=4
        max_modifiers_len=4
        max_default_len=4
        for i in rv_columns:
            if i['attname']:
                if max_column_len < i['attname'].__len__():
                    max_column_len=i['attname'].__len__()
            if i['format_type']:
                if max_type_len < i['format_type'].__len__():
                    max_type_len=i['format_type'].__len__()
            if i['default']:
                if max_type_len < i['default'].__len__():
                    max_default_len=i['default'].__len__()
        first=True
        for i in rv_columns:
            if first==True:
                split_char=' ';
                first=False
            else:
                split_char=',';
            if i['attname']:
                create_sql += " " + split_char + i['attname'].ljust(max_column_len+6)+''
            else:
                create_sql += "" + split_char + ' '.ljust(max_column_len+6)
            if i['format_type']:
                create_sql += ' ' + i['format_type'].ljust(max_type_len +2)
            else:
                create_sql += ' ' + ' '.ljust(max_type_len+2)
            if i['isnull'] and i['isnull']:
                create_sql += ' ' + ' not null '.ljust(8)
            if i['default']:
                create_sql += ' default ' + i['default'].ljust(max_default_len+6)
            create_sql += "\n"
        create_sql += ")"
 
        if rv_reloptions:
            create_sql +=" with ("+str(rv_reloptions).strip('{').strip('}').strip('[').strip(']') +")\n"
            create_sql = create_sql.replace("'",'')
        if rv_distribution2:
            create_sql += 'Distributed by ('
            for i in rv_distribution2:
                create_sql += i['attname'] + ','
            create_sql =create_sql.strip(',')+')'
        elif rv_distribution1:
            create_sql += 'Distributed randomly\n'
        if v_par_parent:
            partitiontype=v_par_info[0]['partitiontype'];
            create_sql +='\nPARTITION BY '+ partitiontype + "("+v_par_parent[0]['columnname']+")\n(\n";
            for i in v_par_info:
                create_sql +=" " +i['partitionboundary']+',\n';
            create_sql=create_sql.strip(',\n');
            create_sql+="\n)"
        create_sql+=";\n\n"
        for i in rv_index:
            create_sql += i['indexdef']+';\n'

        
        get_table_comment="select 'comment on %s %s is '''|| COALESCE (description,'')|| '''' as comment from pg_description where objoid=%s and objsubid=0;" % (table_kind,tablename,table_oid)
        get_column_comment="select 'comment on column %s.'||b.attname ||' is ''' || COALESCE(a.description,'')|| ''' ' as comment from pg_catalog.pg_description a,pg_catalog.pg_attribute b where objoid=%s and a.objoid=b.attrelid and a.objsubid=b.attnum;" % (tablename,table_oid)
        rv_table_comment=plpy.execute(get_table_comment);
        rv_column_comment=plpy.execute(get_column_comment);


        for i in rv_table_comment:
            create_sql += i['comment']+';\n'
        for i in rv_column_comment:
            create_sql +=i['comment']+';\n'
        return create_sql;

$$ LANGUAGE plpythonu;

--获取数据库中所有表的建表语句
创建存放建表语句的表
create table tab_structure(context text) distributed by context;
CREATE OR REPLACE FUNCTION get_cts(username varchar)
RETURNS void AS
$FUNCTION$
DECLARE 
s_tab 					varchar;
schema_name 			varchar;
tabname 				varchar;
vsql					text;
table_name cursor for select tablename from pg_tables where lower(tableowner) = username;
BEGIN
	truncate table tab_structure;
	select schemaname into schema_name from pg_tables where lower(tableowner) = username;
	open table_name;
	loop
		fetch table_name into tabname;
		if not found then
			exit;
		end if;
		s_tab = schema_name ||'.' || tabname;
		vsql = 'insert into tab_structure select get_table_structure('''||s_tab||''')';
		execute vsql;
		raise notice '%  ',s_tab ;
	end loop;
END;
$FUNCTION$
LANGUAGE PLPGSQL;

测试：

执行获取整个用户名对象下的建表语句函数

testdb=# select get_cts('test'); --此处的test为用户名
NOTICE:  public.t
NOTICE:  public.t1
NOTICE:  public.tab_structure
 get_cts 
---------
 
(1 row)

查看存放建表语句的表 tab_structure;

testdb=# select * from tab_structure ;
                context                 
----------------------------------------
 create table public.t (                
   id               integer             
 )Distributed by (id);                  
                                        
 
 create table public.t1 (               
   id               integer             
  ,name             character varying   
 )Distributed by (id);                  
                                        
 
 create table public.tab_structure (    
   context          text                
 )Distributed by (context); 

因为get_table_structure(schema.tablename)这个函数，一次只能获取一张表的表结构。
因此如果不使用pg_dump，仅仅是为了获取所有表的原始建表语句，可以使用get_cts(username) 这个函数

将原始建表语句存放于文件中执行以下命令：

[gpadmin@mpp01 ~]$ psql -U test -d testdb -At -c "select get_cts('test')"
NOTICE:  public.t
NOTICE:  public.t1
NOTICE:  public.tab_structure

[gpadmin@mpp01 ~]$ psql -U test -d testdb -At -c "select * from tab_structure" >cts.sql

查看文件cts.sql

[gpadmin@mpp01 ~]$ cat cts.sql 
create table public.t (
  id               integer  
)Distributed by (id);


create table public.t1 (
  id               integer            
 ,name             character varying  
)Distributed by (id);


create table public.tab_structure (
  context          text  
)Distributed by (context);

很方便，供参考。