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PostgreSQL修改表结构提示有试图依赖的处理方法

秦瑟读书 2022-06-23 阅读 99

修改表结构提示有试图依赖的处理方法

1.适用范围

PG、Vastbase G100

2.报错信息

PostgreSQL修改表结构提示有试图依赖的处理方法_PostgreSQL

3.只修改字段长度 修改 pg_attribute

通过修改 pg_attribute 基表的方式来绕开这个限制 

PostgreSQL修改表结构提示有试图依赖的处理方法_数据库_02

#通过表名查出attrelid
SELECT relname, attname,attnum,attrelid,attname FROM pg_class c,pg_attribute attr WHERE relname = '表名' AND c.oid = attr.attrelid;

#修改字段长度 注意 varchar类型额外加4
update pg_attribute set atttypmod =34 WHERE attrelid ='a'::regclass AND attname = '字段名';

#查询修改后长度
SELECT atttypmod FROM pg_attribute WHERE attrelid = '3648177'::regclass AND attname = '字段名';
  • 操作步骤
select viewname,definition from pg_views where definition like '%ldcode%';
  • 查询该表上的所有视图

4.修改字段类型

修改字段类型这种情况 就需要把删除视图、修改字段、创建视图放到一个事务下执行,但是如果嵌套的视图比较多就很麻烦。以下方法可以解决

  • PG12之前版本

https://gist.github.com/mateuszwenus/11187288(PG12之前版本) 1)先执行deps_save_and_drop_dependencies函数将嵌套的视图找出删除 2)修改字段类型 3)执行deps_restore_dependencies 恢复嵌套视图 例:

BEGIN;

select deps_save_and_drop_dependencies('public', 'a');

alter table a alter name type varchar(30);

select deps_restore_dependencies('public', 'a');

COMMIT
create table deps_saved_ddl
(
deps_id serial primary key,
deps_view_schema varchar(255),
deps_view_name varchar(255),
deps_ddl_to_run text
);

create or replace function deps_save_and_drop_dependencies(p_view_schema varchar, p_view_name varchar) returns void as
$$
declare
v_curr record;
begin
for v_curr in
(
select obj_schema, obj_name, obj_type from
(
with recursive recursive_deps(obj_schema, obj_name, obj_type, depth) as
(
select p_view_schema, p_view_name, null::varchar, 0
union
select dep_schema::varchar, dep_name::varchar, dep_type::varchar, recursive_deps.depth + 1 from
(
select ref_nsp.nspname ref_schema, ref_cl.relname ref_name,
rwr_cl.relkind dep_type,
rwr_nsp.nspname dep_schema,
rwr_cl.relname dep_name
from pg_depend dep
join pg_class ref_cl on dep.refobjid = ref_cl.oid
join pg_namespace ref_nsp on ref_cl.relnamespace = ref_nsp.oid
join pg_rewrite rwr on dep.objid = rwr.oid
join pg_class rwr_cl on rwr.ev_class = rwr_cl.oid
join pg_namespace rwr_nsp on rwr_cl.relnamespace = rwr_nsp.oid
where dep.deptype = 'n'
and dep.classid = 'pg_rewrite'::regclass
) deps
join recursive_deps on deps.ref_schema = recursive_deps.obj_schema and deps.ref_name = recursive_deps.obj_name
where (deps.ref_schema != deps.dep_schema or deps.ref_name != deps.dep_name)
)
select obj_schema, obj_name, obj_type, depth
from recursive_deps
where depth > 0
) t
group by obj_schema, obj_name, obj_type
order by max(depth) desc
) loop

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'COMMENT ON ' ||
case
when c.relkind = 'v' then 'VIEW'
when c.relkind = 'm' then 'MATERIALIZED VIEW'
else ''
end
|| ' ' || n.nspname || '.' || c.relname || ' IS ''' || replace(d.description, '''', '''''') || ''';'
from pg_class c
join pg_namespace n on n.oid = c.relnamespace
join pg_description d on d.objoid = c.oid and d.objsubid = 0
where n.nspname = v_curr.obj_schema and c.relname = v_curr.obj_name and d.description is not null;

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'COMMENT ON COLUMN ' || n.nspname || '.' || c.relname || '.' || a.attname || ' IS ''' || replace(d.description, '''', '''''') || ''';'
from pg_class c
join pg_attribute a on c.oid = a.attrelid
join pg_namespace n on n.oid = c.relnamespace
join pg_description d on d.objoid = c.oid and d.objsubid = a.attnum
where n.nspname = v_curr.obj_schema and c.relname = v_curr.obj_name and d.description is not null;

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'GRANT ' || privilege_type || ' ON ' || table_schema || '.' || table_name || ' TO ' || grantee
from information_schema.role_table_grants
where table_schema = v_curr.obj_schema and table_name = v_curr.obj_name;

if v_curr.obj_type = 'v' then
insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'CREATE VIEW ' || v_curr.obj_schema || '.' || v_curr.obj_name || ' AS ' || view_definition
from information_schema.views
where table_schema = v_curr.obj_schema and table_name = v_curr.obj_name;
elsif v_curr.obj_type = 'm' then
insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'CREATE MATERIALIZED VIEW ' || v_curr.obj_schema || '.' || v_curr.obj_name || ' AS ' || definition
from pg_matviews
where schemaname = v_curr.obj_schema and matviewname = v_curr.obj_name;
end if;

execute 'DROP ' ||
case
when v_curr.obj_type = 'v' then 'VIEW'
when v_curr.obj_type = 'm' then 'MATERIALIZED VIEW'
end
|| ' ' || v_curr.obj_schema || '.' || v_curr.obj_name;

end loop;
end;
$$
LANGUAGE plpgsql;

create or replace function deps_restore_dependencies(p_view_schema varchar, p_view_name varchar) returns void as
$$
declare
v_curr record;
begin
for v_curr in
(
select deps_ddl_to_run
from deps_saved_ddl
where deps_view_schema = p_view_schema and deps_view_name = p_view_name
order by deps_id desc
) loop
execute v_curr.deps_ddl_to_run;
end loop;
delete from deps_saved_ddl
where deps_view_schema = p_view_schema and deps_view_name = p_view_name;
end;
$$
LANGUAGE plpgsql;
  • 前置条件
  • PG12之后的版本

​​ https://gist.github.com/briandignan/03ef42e78434658cf27f052e2f0798e8 ​​

create table if not exists deps_saved_ddl
(
deps_id serial primary key,
deps_view_schema name,
deps_view_name name,
deps_ddl_to_run text
);

create or replace function deps_save_and_drop_dependencies(p_view_schema name, p_view_name name) returns void as
$$
declare
v_curr record;
begin
for v_curr in
(
select obj_schema, obj_name, obj_type from
(
with recursive recursive_deps(obj_schema, obj_name, obj_type, depth) as
(
select p_view_schema, p_view_name, null::char, 0
union
select dep_schema::name, dep_name::name, dep_type::char, recursive_deps.depth + 1 from
(
select ref_nsp.nspname ref_schema, ref_cl.relname ref_name,
rwr_cl.relkind dep_type,
rwr_nsp.nspname dep_schema,
rwr_cl.relname dep_name
from pg_depend dep
join pg_class ref_cl on dep.refobjid = ref_cl.oid
join pg_namespace ref_nsp on ref_cl.relnamespace = ref_nsp.oid
join pg_rewrite rwr on dep.objid = rwr.oid
join pg_class rwr_cl on rwr.ev_class = rwr_cl.oid
join pg_namespace rwr_nsp on rwr_cl.relnamespace = rwr_nsp.oid
where dep.deptype = 'n'
and dep.classid = 'pg_rewrite'::regclass
) deps
join recursive_deps on deps.ref_schema = recursive_deps.obj_schema and deps.ref_name = recursive_deps.obj_name
where (deps.ref_schema != deps.dep_schema or deps.ref_name != deps.dep_name)
)
select obj_schema, obj_name, obj_type, depth
from recursive_deps
where depth > 0
) t
group by obj_schema, obj_name, obj_type
order by max(depth) desc
) loop

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select distinct p_view_schema, p_view_name, indexdef
from pg_indexes
where schemaname = v_curr.obj_schema
and tablename = v_curr.obj_name;

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select distinct tablename, rulename, definition
from pg_rules
where schemaname = v_curr.obj_schema
and tablename = v_curr.obj_name;

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'COMMENT ON ' ||
case
when c.relkind = 'v' then 'VIEW'
when c.relkind = 'm' then 'MATERIALIZED VIEW'
else ''
end
|| ' ' || n.nspname || '.' || c.relname || ' IS ''' || replace(d.description, '''', '''''') || ''';'
from pg_class c
join pg_namespace n on n.oid = c.relnamespace
join pg_description d on d.objoid = c.oid and d.objsubid = 0
where n.nspname = v_curr.obj_schema and c.relname = v_curr.obj_name and d.description is not null;

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'COMMENT ON COLUMN ' || n.nspname || '.' || c.relname || '.' || a.attname || ' IS ''' || replace(d.description, '''', '''''') || ''';'
from pg_class c
join pg_attribute a on c.oid = a.attrelid
join pg_namespace n on n.oid = c.relnamespace
join pg_description d on d.objoid = c.oid and d.objsubid = a.attnum
where n.nspname = v_curr.obj_schema and c.relname = v_curr.obj_name and d.description is not null;

insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'GRANT ' || privilege_type || ' ON ' || table_schema || '.' || quote_ident(table_name) || ' TO ' || grantee
from information_schema.role_table_grants
where table_schema = v_curr.obj_schema and table_name = v_curr.obj_name;

if v_curr.obj_type = 'v' then
insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'CREATE VIEW ' || v_curr.obj_schema || '.' || quote_ident(v_curr.obj_name) || ' AS ' || view_definition
from information_schema.views
where table_schema = v_curr.obj_schema and table_name = v_curr.obj_name;
elsif v_curr.obj_type = 'm' then
insert into deps_saved_ddl(deps_view_schema, deps_view_name, deps_ddl_to_run)
select p_view_schema, p_view_name, 'CREATE MATERIALIZED VIEW ' || v_curr.obj_schema || '.' || quote_ident(v_curr.obj_name) || ' AS ' || definition
from pg_matviews
where schemaname = v_curr.obj_schema and matviewname = v_curr.obj_name;
end if;

execute 'DROP ' ||
case
when v_curr.obj_type = 'v' then 'VIEW'
when v_curr.obj_type = 'm' then 'MATERIALIZED VIEW'
end
|| ' ' || v_curr.obj_schema || '.' || quote_ident(v_curr.obj_name);

end loop;
end;
$$
LANGUAGE plpgsql;

create or replace function deps_restore_dependencies(p_view_schema name, p_view_name name) returns void as
$$
declare
v_curr record;
begin
for v_curr in
(
select deps_ddl_to_run
from deps_saved_ddl
where deps_view_schema = p_view_schema and deps_view_name = p_view_name
order by deps_id desc
) loop
execute v_curr.deps_ddl_to_run;
end loop;
delete from deps_saved_ddl
where deps_view_schema = p_view_schema and deps_view_name = p_view_name;
end;
$$
LANGUAGE plpgsql;

查询DB视图依赖关系

with recursive view_tree(parent_schema, parent_obj, child_schema, child_obj, ind, ord) as 
(
select vtu_parent.view_schema, vtu_parent.view_name,
vtu_parent.table_schema, vtu_parent.table_name,
'', array[row_number() over (order by view_schema, view_name)]
from information_schema.view_table_usage vtu_parent
where vtu_parent.view_schema = 'public' and vtu_parent.view_name = 'v_department_sales'
union all
select vtu_child.view_schema, vtu_child.view_name,
vtu_child.table_schema, vtu_child.table_name,
vtu_parent.ind || ' ',
vtu_parent.ord || (row_number() over (order by view_schema, view_name))
from view_tree vtu_parent, information_schema.view_table_usage vtu_child
where vtu_child.view_schema = vtu_parent.child_schema
and vtu_child.view_name = vtu_parent.child_obj
)
select tree.ind || tree.parent_schema || '.' || tree.parent_obj
|| ' depends on ' || tree.child_schema || '.' || tree.child_obj txt, tree.ord
from view_tree tree
order by ord;
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