我正在寻找一种方法,为我在Postgres中所有的表找到行数。我知道我可以一次做一张表:
SELECT count(*) FROM table_name;
但我想看看所有表的行数,然后按它排序,以了解所有表的大小。
我正在寻找一种方法,为我在Postgres中所有的表找到行数。我知道我可以一次做一张表:
SELECT count(*) FROM table_name;
但我想看看所有表的行数,然后按它排序,以了解所有表的大小。
当前回答
不确定bash中的答案对您来说是否可以接受,但FWIW…
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='public'
\""
TABLENAMES=$(export PGPASSWORD=test; eval "$PGCOMMAND")
for TABLENAME in $TABLENAMES; do
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT '$TABLENAME',
count(*)
FROM $TABLENAME
\""
eval "$PGCOMMAND"
done
其他回答
如果您不介意可能过时的数据,您可以访问查询优化器使用的相同统计信息。
喜欢的东西:
SELECT relname, n_tup_ins - n_tup_del as rowcount FROM pg_stat_all_tables;
要获得估计,请参阅格雷格·史密斯的答案。
为了得到确切的数字,到目前为止,其他答案都受到一些问题的困扰,其中一些问题很严重(见下文)。这里有一个版本,希望更好:
CREATE FUNCTION rowcount_all(schema_name text default 'public')
RETURNS table(table_name text, cnt bigint) as
$$
declare
table_name text;
begin
for table_name in SELECT c.relname FROM pg_class c
JOIN pg_namespace s ON (c.relnamespace=s.oid)
WHERE c.relkind = 'r' AND s.nspname=schema_name
LOOP
RETURN QUERY EXECUTE format('select cast(%L as text),count(*) from %I.%I',
table_name, schema_name, table_name);
END LOOP;
end
$$ language plpgsql;
它接受模式名作为参数,如果没有给出参数,则接受public。
要使用特定的模式列表或来自查询的列表而不修改函数,可以从查询中调用它,如下所示:
WITH rc(schema_name,tbl) AS (
select s.n,rowcount_all(s.n) from (values ('schema1'),('schema2')) as s(n)
)
SELECT schema_name,(tbl).* FROM rc;
这将生成一个包含模式、表和行计数的3列输出。
下面是这个函数避免的其他答案中的一些问题:
Table and schema names shouldn't be injected into executable SQL without being quoted, either with quote_ident or with the more modern format() function with its %I format string. Otherwise some malicious person may name their table tablename;DROP TABLE other_table which is perfectly valid as a table name. Even without the SQL injection and funny characters problems, table name may exist in variants differing by case. If a table is named ABCD and another one abcd, the SELECT count(*) FROM... must use a quoted name otherwise it will skip ABCD and count abcd twice. The %I of format does this automatically. information_schema.tables lists custom composite types in addition to tables, even when table_type is 'BASE TABLE' (!). As a consequence, we can't iterate oninformation_schema.tables, otherwise we risk having select count(*) from name_of_composite_type and that would fail. OTOH pg_class where relkind='r' should always work fine. The type of COUNT() is bigint, not int. Tables with more than 2.15 billion rows may exist (running a count(*) on them is a bad idea, though). A permanent type need not to be created for a function to return a resultset with several columns. RETURNS TABLE(definition...) is a better alternative.
对于那些试图评估他们需要哪一个Heroku计划,又不能等待Heroku的慢行计数器刷新的人来说,一个简单实用的答案是:
基本上你想在psql中运行\dt,将结果复制到你最喜欢的文本编辑器中(它看起来像这样:
public | auth_group | table | axrsosvelhutvw
public | auth_group_permissions | table | axrsosvelhutvw
public | auth_permission | table | axrsosvelhutvw
public | auth_user | table | axrsosvelhutvw
public | auth_user_groups | table | axrsosvelhutvw
public | auth_user_user_permissions | table | axrsosvelhutvw
public | background_task | table | axrsosvelhutvw
public | django_admin_log | table | axrsosvelhutvw
public | django_content_type | table | axrsosvelhutvw
public | django_migrations | table | axrsosvelhutvw
public | django_session | table | axrsosvelhutvw
public | exercises_assignment | table | axrsosvelhutvw
),然后运行regex搜索并替换,如下所示:
^[^|]*\|\s+([^|]*?)\s+\| table \|.*$
to:
select '\1', count(*) from \1 union/g
这将会给你一个非常类似的结果:
select 'auth_group', count(*) from auth_group union
select 'auth_group_permissions', count(*) from auth_group_permissions union
select 'auth_permission', count(*) from auth_permission union
select 'auth_user', count(*) from auth_user union
select 'auth_user_groups', count(*) from auth_user_groups union
select 'auth_user_user_permissions', count(*) from auth_user_user_permissions union
select 'background_task', count(*) from background_task union
select 'django_admin_log', count(*) from django_admin_log union
select 'django_content_type', count(*) from django_content_type union
select 'django_migrations', count(*) from django_migrations union
select 'django_session', count(*) from django_session
;
(您需要删除最后一个联合,并手动在末尾添加分号)
在psql中运行它,就完成了。
?column? | count
--------------------------------+-------
auth_group_permissions | 0
auth_user_user_permissions | 0
django_session | 1306
django_content_type | 17
auth_user_groups | 162
django_admin_log | 9106
django_migrations | 19
[..]
不确定bash中的答案对您来说是否可以接受,但FWIW…
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='public'
\""
TABLENAMES=$(export PGPASSWORD=test; eval "$PGCOMMAND")
for TABLENAME in $TABLENAMES; do
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT '$TABLENAME',
count(*)
FROM $TABLENAME
\""
eval "$PGCOMMAND"
done
我做了一个小的变化,包括所有的表,也是非公共的表。
CREATE TYPE table_count AS (table_schema TEXT,table_name TEXT, num_rows INTEGER);
CREATE OR REPLACE FUNCTION count_em_all () RETURNS SETOF table_count AS '
DECLARE
the_count RECORD;
t_name RECORD;
r table_count%ROWTYPE;
BEGIN
FOR t_name IN
SELECT table_schema,table_name
FROM information_schema.tables
where table_schema !=''pg_catalog''
and table_schema !=''information_schema''
ORDER BY 1,2
LOOP
FOR the_count IN EXECUTE ''SELECT COUNT(*) AS "count" FROM '' || t_name.table_schema||''.''||t_name.table_name
LOOP
END LOOP;
r.table_schema := t_name.table_schema;
r.table_name := t_name.table_name;
r.num_rows := the_count.count;
RETURN NEXT r;
END LOOP;
RETURN;
END;
' LANGUAGE plpgsql;
使用select count_em_all();叫它。
希望这对你有用。 保罗