取消记录数据库中的所有表

Question

我想通过使所有表UNLOGGED来减少本地测试执行时间。我想编写sql脚本，它将在所有转换后运行并使它们UNLOGGED。但是我发现了问题 - 表与FK相互关联，因此postgresql禁止使表UNLOGGED(通过ALTER(，如果它与尚未UNLOGGED的其他表相关。

有没有更好的方法，然后按正确的顺序列出所有ALTER - 我有超过 150 张桌子？例如，在数据库级别应用它。

Answer 1

恐怕你必须按照正确的顺序改变它们。您可以先选择 https://www.postgresql.org/docs/current/static/catalog-pg-constraint.html 和循环来引用表，然后再更改其余部分：

begin;
do
$$
declare
 _r record;
 _t text;
begin
 for _r in (
    select relname,conrelid
    from pg_constraint
    join pg_class c on c.oid = conrelid
    where confkey is not null
    order by conrelid desc
    -- Order by oid with logic that you should start from latest added objects to earliest - of course it does not garantee anything
 ) loop
    _t := format('alter table %I set unlogged',_r.relname);
    raise info '%',_t;
    execute _t;
 end loop;
  for _r in (select tablename from pg_tables where tablename like 's%' and schemaname = 'public') loop
    _t := format('alter table %I set unlogged',_r.tablename);
    raise info '%',_t;
    execute _t;
 end loop;
end;
$$
;
rollback;

无论如何，

如果您有递归 FK，它将失败：

t=# create table s134(i int primary key, e int);
CREATE TABLE
t=# create table s135(i int references s134(i), e int primary key);
CREATE TABLE
t=# alter table s134 add constraint c1 foreign key (e) references s135(e);
ALTER TABLE
t=# alter table s134 set unlogged;
ERROR:  could not change table "s134" to unlogged because it references logged table "s135"
t=# alter table s135 set unlogged;
ERROR:  could not change table "s135" to unlogged because it references logged table "s134"

但我相信你无论如何都不会做到这一点。

另外不要忘记，在不干净关机或失败后，未记录的表将被截断。

最后，您说"毕竟转换后" - 如果您创建，转换等，也许您应该创建未记录的它们?..

Answer 2

我会删除并重新创建所有外键。您可以自动执行此操作。

以下查询将为所有外键生成必要的 DDL 语句。您需要将其输出保存到一个文件中，稍后可以使用该文件还原所有外键。

select format('alter table %I.%I add constraint %I ',  ns.nspname, tb.relname, conname)|| 
       pg_get_constraintdef(c.oid, true)||';' as ddl
from pg_constraint c
  join pg_class tb on tb.oid = c.conrelid
  join pg_namespace ns on ns.oid = tb.relnamespace
where ns.nspname not in ('pg_catalog', 'information_schema')
  and ns.nspname not like 'pg_temp%'
  and c.contype in ('f')

然后生成一个脚本来删除所有约束：

select format('alter table %I.%I drop constraint %I cascade;', ns.nspname, tb.relname, c.conname) as ddl
from pg_constraint c
  join pg_class tb on tb.oid = c.conrelid
  join pg_namespace ns on ns.oid = tb.relnamespace
where ns.nspname not in ('pg_catalog', 'information_schema')
  and ns.nspname not like 'pg_temp%'
  and c.contype in ('f');

当然，在删除 FK 之前，您必须运行查询以生成 FK ;)

Answer 3

我对接受的答案有困难，因为它依赖于启发式(可能不适用(来正确排序。我使用(有点冗长的(递归查询重新设计了建议的答案，该查询允许人们获得所需的确切顺序。我没有用递归 FK 测试过它，我怀疑递归查询不会终止。请注意，我已将查询限制为应用于public架构中的表，并根据您自己的需要进行修改。

取消记录所有表：

do
$$
    declare
        _r record;
        _t text;
    begin
        for _r in (
            WITH RECURSIVE constraints AS (
                SELECT
                    tc.table_schema
                     , tc.table_name
                     , kcu.column_name
                     , ccu.table_name AS foreign_table_name
                FROM
                    information_schema.table_constraints AS tc
                        LEFT OUTER JOIN information_schema.key_column_usage AS kcu
                                        ON tc.constraint_name = kcu.constraint_name
                                            AND tc.table_schema = kcu.table_schema
                        LEFT OUTER JOIN information_schema.constraint_column_usage AS ccu
                                        ON ccu.constraint_name = tc.constraint_name
                                            AND ccu.table_schema = tc.table_schema
                WHERE (tc.constraint_type IS NULL OR tc.constraint_type = 'FOREIGN KEY'))
               , tables_and_constraints AS (
                SELECT
                    t.table_schema
                     , t.table_name
                     , c.foreign_table_name
                FROM information_schema.tables AS t
                         LEFT JOIN constraints AS c USING (table_name)
                WHERE t.table_type <> 'VIEW')
               , dependent_table_constraints AS (
                SELECT tc.table_schema
                     , tc.table_name
                     , tc.foreign_table_name
                     , 0 AS depth
                FROM tables_and_constraints AS tc
                WHERE foreign_table_name IS NULL
                UNION
                SELECT tc.table_schema
                     , tc.table_name
                     , tc.foreign_table_name
                     , dtc.depth + 1
                FROM tables_and_constraints AS tc
                         INNER JOIN dependent_table_constraints AS dtc ON tc.foreign_table_name = dtc.table_name
            ) SELECT table_name, max(depth) as depth FROM dependent_table_constraints
            WHERE table_schema = 'public'
            GROUP BY table_name
            ORDER BY depth DESC
        ) loop
                _t := format('ALTER TABLE %I SET UNLOGGED',_r.table_name);
                raise info '%',_t;
                execute _t;
            end loop;
    end;
$$
;

重新记录所有表：

do
$$
    declare
        _r record;
        _t text;
    begin
        for _r in (
            WITH RECURSIVE constraints AS (
                SELECT
                    tc.table_schema
                     , tc.table_name
                     , kcu.column_name
                     , ccu.table_name AS foreign_table_name
                FROM
                    information_schema.table_constraints AS tc
                        LEFT OUTER JOIN information_schema.key_column_usage AS kcu
                                        ON tc.constraint_name = kcu.constraint_name
                                            AND tc.table_schema = kcu.table_schema
                        LEFT OUTER JOIN information_schema.constraint_column_usage AS ccu
                                        ON ccu.constraint_name = tc.constraint_name
                                            AND ccu.table_schema = tc.table_schema
                WHERE (tc.constraint_type IS NULL OR tc.constraint_type = 'FOREIGN KEY'))
               , tables_and_constraints AS (
                SELECT
                    t.table_schema
                     , t.table_name
                     , c.foreign_table_name
                FROM information_schema.tables AS t
                         LEFT JOIN constraints AS c USING (table_name)
                WHERE t.table_type <> 'VIEW')
               , dependent_table_constraints AS (
                SELECT tc.table_schema
                     , tc.table_name
                     , tc.foreign_table_name
                     , 0 AS depth
                FROM tables_and_constraints AS tc
                WHERE foreign_table_name IS NULL
                UNION
                SELECT tc.table_schema
                     , tc.table_name
                     , tc.foreign_table_name
                     , dtc.depth + 1
                FROM tables_and_constraints AS tc
                         INNER JOIN dependent_table_constraints AS dtc ON tc.foreign_table_name = dtc.table_name
            ) SELECT table_name, max(depth) as depth FROM dependent_table_constraints
            WHERE table_schema = 'public'
            GROUP BY table_name
            ORDER BY depth ASC
        ) loop
                _t := format('ALTER TABLE %I SET LOGGED',_r.table_name);
                raise info '%',_t;
                execute _t;
            end loop;
    end;
$$
;