一、数据库集群信息
1、gp_segment_configration
2、pg_filespace_entry
这两个表是在pg_global表空间下面的，是全局表。
用来查看集群segment信息，比如segment个数。
二、常用数据字典表
1、pg_class
保存了所有表、视图、序列、索引元数据信息，每个DDL/DML操作都必须跟这个表发生关系。
2、pg_attribute
记录字段的内容
3、gp_distribution_policy
记录表的分布键
4、pg_statistic 和 pg_stats
数据库中表的统计信息保存在pg_statistic中
pg_stats可以方便帮我们查看pg_statistic的内容
5、pg_partition
记录分区表的信息
6、pg_partition_rule
分区表的分区规则
7、pg_partitions
三、字典表的应用
1、查看表的信息
1）从catalog中查询
2）从information_schema查询
select * from information_schema.tables where table_name ='';
1、获取字段信息
1）从catalog中查询
SELECT a.attname,pg_catalog.format_type(a.atttypid,( pg_catalog.pg_attribute a, a.atttypmod) AS data_type
FROM pg_catalog.pg_attribute a,
(SELECT c. oid
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n
ON n.oid = c.relnamespace
WHERE c.relname = 'pg_class'
AND n.nspname = 'pg_catalog'
) b
WHERE a.attrelid = b.oid
AND a.attnum > 0
AND NOT a.attisdropped ORDER BY a.attnum;
FROM pg_catalog.pg_attribute a,
(SELECT c. oid
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n
ON n.oid = c.relnamespace
WHERE c.relname = 'pg_class'
AND n.nspname = 'pg_catalog'
) b
WHERE a.attrelid = b.oid
AND a.attnum > 0
AND NOT a.attisdropped ORDER BY a.attnum;
使用regclass就会简化很多：
SELECT a.attname,pg_catalog.format_type(a.atttypid, a.atttypmod) AS data_type
FROM pg_catalog.pg_attribute a
WHERE a.attrelid ='pg_catalog.pg_class'::regclass
AND a.attnum > 0
AND NOT a.attisdropped ORDER BY a.attnum;
SELECT a.attname,pg_catalog.format_type(a.atttypid, a.atttypmod) AS data_type
FROM pg_catalog.pg_attribute a
WHERE a.attrelid ='pg_catalog.pg_class'::regclass
AND a.attnum > 0
AND NOT a.attisdropped ORDER BY a.attnum;
2）从information_schema查询
select * from information_schema.columns where table_name = '';
2、获取表的分布键
select a.attrnums[i.i],b.attname,a.localoid::regclass
from gp_distribution_policy a,
(select generate_series(1,10))i (i),
pg_attribute b
where a.attrnums[i.i) is not null
and a.localoid=b.attrelid
and a.attrnums[i.i]=b.attnum
and a.localoid='public.cxfa2 '::regclass
order by i.i;
3、获取一个视图定义
testDB=# create table cxfa( a int) distributed by (a);
CREATE TABLE
testDB=# create view v_cxfa as select * from cxfa;
CREATE VIEW
testDB=# select pg_get_viewdef('v_cxfa', true);
SELECT cxfa.a FROM cxfa;
(1 row)
4、查询备注信息
1）获取表的备注
select COALESCE(description, * *) as comment from pg_description where objoid=‘cxfa*::regclass and objsubid=0;
2）获取字段的备注
select b.attname as columnname, COALESCE(a.description,'') as comment
from pg_catalog.pg_description a,pg_catalog.pg_attribute b
where objoid='cxfa'::regclass
and a.objoid=b.attrelid
and a.objsubid=b.attnum;
5、获取数据据库建表语句
1）调用plpythonu
CREATE PROCEDURAL LANGUAGE plpythonu;
2）创建存储过程
create or replace function get_table_structure(tablename text) # 表名格式为 tableschema.table_name
returns text
as $$
try:
table_name = tablename.lower().split('.')[1]
returns text
as $$
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) #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
' % (tablename)
create_sql += rv_viewdef[0]['viewdef']+'
';
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 (
' % (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=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 += "
"
create_sql += ")"
if rv_reloptions:
create_sql +=" with ("+str(rv_reloptions).strip('{').strip('}').strip('[').strip(']') +")
"
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
'
if v_par_parent:
partitiontype=v_par_info[0]['partitiontype'];
create_sql +='
PARTITION BY '+ partitiontype + "("+v_par_parent[0]['columnname']+")
(
";
for i in v_par_info:
create_sql +=" " +i['partitionboundary']+',
';
create_sql=create_sql.strip(',
');
create_sql+="
)"
create_sql+=";
"
for i in rv_index:
create_sql += i['indexdef']+';
'
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']+';
'
for i in rv_column_comment:
create_sql +=i['comment']+';
'
return create_sql;
$$ LANGUAGE plpythonu;
3）使用例子
testdb=# SELECT get_table_structure('public.tb1_partition_range_yyyymmdd');
get_table_structure
-------------------------------------------------------------------------------------------------------------------
create table public.tb1_partition_range_yyyymmdd (
id numeric，
yyyymmdd date
) with (appendonly=true, compresslevel=5)
Distributed by (id)
PARTITION BY range(yyyymmdd)
(
PARTITION p20120811 START ('2012-08-11'::date) END ('2012-08-12'::date) WITH (appendonly=true, compresslevel=5),
PARTITION p20120812 START ('2012-08-12'::date) END ('2012-08-13'::date) WITH (appendonly=true, compresslevel=5)
);
CREATE INDEX idx_yyyymmdd ON tb1_partition_range_yyyymmdd USING btree (yyyymmdd);
5、查看表的依赖关系
pg_depend