create or replace function get_table_structure(tablename text)    # 表名格式为 tableschema.table_namereturns 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)      #plpy.execute(query [, max-rows])if not rv_oid:return 'Did not find any relation named"'+tablename +'".'except (Error):return 'Did not find any relation named"'+tablename +'".'table_oid=rv_oid[0]['oid']rv_reloptions=rv_oid[0]['reloptions'] # 访问方法特定的选项，使用"keyword=value"格式的字符串
rv_relkind=rv_oid[0]['relkind']create_sql="";table_kind='table';if rv_relkind !='r' and rv_relkind !='v':  # r:普通表， v:视图， c:复合类型， t:表， o:内部 AO 节点文件， 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:
#获取行
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)#获取分布键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)
#获取索引
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=10max_type_len=4max_modifiers_len=4max_default_len=4for 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=Truefor i in rv_columns:if first==True:split_char=' ';first=Falseelse: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;