Question

您好我正在尝试检索现有表的架构。我是mysql开发人员，我正在尝试使用amazon redshift。如何导出现有表的架构。在mysql中我们可以使用show create table命令。

SHOW CREATE TABLE tblName;

Answer 1

此查询将以create语句的形式为您提供完整的模式定义，包括Redshift特定属性分发类型/键，排序键，主键和列编码，以及提供设置所有者的alter table语句给当前的老板。它唯一不能告诉你的是外键。我正在研究后者，但RS中存在一个当前特权问题，导致我们无法查询正确的表格。这个查询可以使用一些调整，但我没有时间或需要进一步工作。

select pk.pkey, tm.schemaname||'.'||tm.tablename, 'create table '||tm.schemaname||'.'||tm.tablename
||' ('
||cp.coldef
-- primary key
||decode(pk.pkey,null,'',pk.pkey)
-- diststyle and dist key
||decode(d.distkey,null,') diststyle '||dist_style||' ',d.distkey)
--sort key 
|| (select decode(skey,null,'',skey) from  (select 
' sortkey(' ||substr(array_to_string(
                 array( select ','||cast(column_name as varchar(100))  as str from
                       (select column_name from information_schema.columns col where  col.table_schema= tm.schemaname and col.table_name=tm.tablename) c2
                        join 
                        (-- gives sort cols
                          select attrelid as tableid, attname as colname, attsortkeyord as sort_col_order from pg_attribute pa where 
                          pa.attnum > 0  AND NOT pa.attisdropped AND pa.attsortkeyord > 0
                        ) st on tm.tableid=st.tableid and c2.column_name=st.colname   order by sort_col_order
                      )
                ,'')
              ,2,10000) || ')' as skey
))
||';'
-- additional alter table queries here to set owner
|| 'alter table '||tm.schemaname||'.'||tm.tablename||' owner to "'||tm.owner||'";'   
from 
-- t  master table list
(
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid ,use2.usename as owner, decode(c.reldiststyle,0,'EVEN',1,'KEY',8,'ALL') as dist_style
FROM pg_namespace n, pg_class c,  pg_user use2 
WHERE n.oid = c.relnamespace 
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
AND c.relname <> 'temp_staging_tables_1'
and c.relowner = use2.usesysid
) tm 
-- cp  creates the col params for the create string
join
(select 
substr(str,(charindex('QQQ',str)+3),(charindex('ZZZ',str))-(charindex('QQQ',str)+3)) as tableid
,substr(replace(replace(str,'ZZZ',''),'QQQ'||substr(str,(charindex('QQQ',str)+3),(charindex('ZZZ',str))-(charindex('QQQ',str)+3)),''),2,10000) as coldef
from
( select array_to_string(array(
SELECT  'QQQ'||cast(t.tableid as varchar(10))||'ZZZ'|| ','||column_name||' '|| decode(udt_name,'bpchar','char',udt_name) || decode(character_maximum_length,null,'', '('||cast(character_maximum_length as varchar(9))||')'   )
-- default
|| decode(substr(column_default,2,8),'identity','',null,'',' default '||column_default||' ')
-- nullable
|| decode(is_nullable,'YES',' NULL ','NO',' NOT NULL ') 
-- identity 
|| decode(substr(column_default,2,8),'identity',' identity('||substr(column_default,(charindex('''',column_default)+1), (length(column_default)-charindex('''',reverse(column_default))-charindex('''',column_default)   ) )  ||') ', '')
-- encoding
|| decode(enc,'none','',' encode '||enc)
 as str 
from  
-- ci  all the col info
(
select cast(t.tableid as int), cast(table_schema as varchar(100)), cast(table_name as varchar(100)), cast(column_name as varchar(100)), 
cast(ordinal_position as int), cast(column_default as varchar(100)), cast(is_nullable as varchar(20)) , cast(udt_name as varchar(50))  ,cast(character_maximum_length as int),
 sort_col_order  , decode(d.colname,null,0,1) dist_key , e.enc
from 
(select * from information_schema.columns c where  c.table_schema= t.schemaname and c.table_name=t.tablename) c
left join 
(-- gives sort cols
select attrelid as tableid, attname as colname, attsortkeyord as sort_col_order from pg_attribute a where 
 a.attnum > 0  AND NOT a.attisdropped AND a.attsortkeyord > 0
) s on t.tableid=s.tableid and c.column_name=s.colname
left join 
(-- gives encoding
select attrelid as tableid, attname as colname, format_encoding(a.attencodingtype::integer) AS enc from pg_attribute a where 
 a.attnum > 0  AND NOT a.attisdropped 
) e on t.tableid=e.tableid and c.column_name=e.colname
left join 
-- gives dist col
(select attrelid as tableid, attname as colname from pg_attribute a where
 a.attnum > 0 AND NOT a.attisdropped  AND a.attisdistkey = 't'
) d on t.tableid=d.tableid and c.column_name=d.colname
order by ordinal_position
) ci 
-- for the working array funct
), '') as str
from 
(-- need tableid
 SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid 
 FROM pg_namespace n, pg_class c
 WHERE n.oid = c.relnamespace 
 AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
 ) t 
)) cp on tm.tableid=cp.tableid
-- primary key query here
left join 
(select c.oid as tableid, ', primary key '|| substring(pg_get_indexdef(indexrelid),charindex('(',pg_get_indexdef(indexrelid))-1 ,60) as pkey
 from pg_index i , pg_namespace n, pg_class c 
 where i.indisprimary=true 
 and i.indrelid =c.oid
 and n.oid = c.relnamespace
)  pk on tm.tableid=pk.tableid
-- dist key
left join
(  select 
-- close off the col defs after the primary key 
')' ||
' distkey('|| cast(column_name as varchar(100)) ||')'  as distkey, t.tableid
from information_schema.columns c
join 
(-- need tableid
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid 
FROM pg_namespace n, pg_class c
WHERE n.oid = c.relnamespace 
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
) t on c.table_schema= t.schemaname and c.table_name=t.tablename
join 
-- gives dist col
(select attrelid as tableid, attname as colname from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped  AND a.attisdistkey = 't'
) d on t.tableid=d.tableid and c.column_name=d.colname

) d on tm.tableid=d.tableid 
where tm.schemaname||'.'||tm.tablename='myschema.mytable'

Answer 2

最近我写了一个python脚本来克隆redshift集群之间的表模式。如果您只想要表的列和列类型，可以通过以下方式完成：

select column_name,
  case
    when data_type = 'integer' then 'integer'
    when data_type = 'bigint' then 'bigint'
    when data_type = 'smallint' then 'smallint'
    when data_type = 'text' then 'text'
    when data_type = 'date' then 'date'
    when data_type = 'real' then 'real'
    when data_type = 'boolean' then 'boolean'
    when data_type = 'double precision' then 'float8'
    when data_type = 'timestamp without time zone' then 'timestamp'
    when data_type = 'character' then 'char('||character_maximum_length||')'
    when data_type = 'character varying' then 'varchar('||character_maximum_length||')'
    when data_type = 'numeric' then 'numeric('||numeric_precision||','||numeric_scale||')'
    else 'unknown'
  end as data_type,
  is_nullable,
  column_default
 from information_schema.columns
 where table_schema = 'xxx' and table_name = 'xxx' order by ordinal_position
;

但是如果你需要压缩类型和distkey / sortkeys，你需要查询另一个表：

select * from pg_table_def where tablename = 'xxx' and schemaname='xxx';

Answer 3

如果要使用create语句，约束和触发器获取表结构，可以使用pg_dump实用程序

pg_dump -U user_name -s -t table_name -d db_name
Note: -s used for schema only dump
if you want to take the data only dump , you can use -a switch.

这将输出包含所有约束的create语法。希望这会对你有所帮助。

Answer 4

我没有找到任何完整的解决方案。并编写了一个python脚本：

https://github.com/cxmcc/redshift_show_create_table

它将像pg_dump一样工作，加上处理基本的红移功能，SORTKEY / DISTKEY / DISTSTYLES等。

Answer 5

在Postgres中，您将查询目录。

从psql开始，使用短语到各种命令，使用\?获取其列表（寻求帮助）。因此，无论是：

\d yourtable
\d+ yourtable

要在应用中使用，您需要了解相关的相关查询。运行psql -E（对于echo隐藏查询）而不是普通psql，这是相对简单的。

如果您需要精确的create table语句，请参阅@Anant answer。

Answer 6

显示表在Redshift上不起作用：

window.location

我们可以使用pg_table_def表获取模式：

const animals = [
{name: 'Fluffy', species: 'cat'},
{name: 'Crinkle', species: 'rabbit'},
{name: 'Wally', species: 'dog'},
{name: 'Roo', species: 'dog'},
{name: 'Felix', species: 'cat'},
]

var result = animals.filter(val=>val.species=="dog").map(({name})=>name);

console.log(result);

注意：如果架构不在搜索路径上，请使用以下方式将其添加到搜索路径：

show table <YOUR_TABLE>;
ERROR: syntax error at or near "<YOUR_TABLE>"

Answer 7

您是需要以编程方式还是从psql提示符检索它？

在psql中使用：\ d + tablename

以编程方式，您可以查询此处记录的ANSI标准INFORMATION_SCHEMA视图：

http://www.postgresql.org/docs/9.1/static/information-schema.html

INFORMATION_SCHEMA.TABLES和INFORMATION_SCHEMA.COLUMNS视图应该具备您所需的信息。

Answer 8

一种简单的方法是使用AWS提供的实用程序。您需要做的就是在数据库中创建视图，然后查询该视图以获取任何表ddl。使用此视图的好处是，它还将为您提供原始create table命令中使用的sortkey和distkey。

https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql

创建视图后，即可获取任何表的ddl。您需要这样查询-

select ddl from table where tablename='table_name' and schemaname='schemaname';

注意：群集中可能尚不存在管理架构。因此，您可以在公共架构中创建此视图。

Answer 9

您可以使用AWS Redshift提供的管理视图-https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql

一旦创建了视图，就可以通过运行以下命令获取架构创建脚本：

select * from <db_schema>.v_generate_tbl_ddl where tablename = '<table_name>'

Answer 10

要获取特定表的列数据和架构：

从information_schema.columns中选择*，其中tablename ='<<< em> table_name >>'

要获取表元数据的信息，请触发以下查询

从information_schema.tables中选择*，其中schema ='<<< em> schema_name >>'

Answer 11

以下查询将为您生成表的DDL：

SELECT ddl
FROM admin.v_generate_tbl_ddl
WHERE schemaname = '<schemaname>'
AND tablename in (
'<tablename>');

Answer 12

以下命令将起作用：

mysql > show create table test.users_info;

Redshift/postgress >pg_dump -U root-w --no-password -h 62.36.11.547 -p 5439  -s -t test.users_info ;

在Redshift中获取表模式

12 个答案: