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
您可以使用此查询生成所有表名及其计数
select ' select '''|| tablename ||''', count(*) from ' || tablename ||'
union' from pg_tables where schemaname='public';
上述查询的结果将是
select 'dim_date', count(*) from dim_date union
select 'dim_store', count(*) from dim_store union
select 'dim_product', count(*) from dim_product union
select 'dim_employee', count(*) from dim_employee union
您需要删除最后一个联合符,并在末尾添加分号!!
select 'dim_date', count(*) from dim_date union
select 'dim_store', count(*) from dim_store union
select 'dim_product', count(*) from dim_product union
select 'dim_employee', count(*) from dim_employee **;**
跑! !
其他回答
如果您在psql shell中,使用\gexec允许您执行syed的答案和Aur的答案中描述的语法,而无需在外部文本编辑器中手动编辑。
with x (y) as (
select
'select count(*), '''||
tablename||
''' as "tablename" from '||
tablename||' '
from pg_tables
where schemaname='public'
)
select
string_agg(y,' union all '||chr(10)) || ' order by tablename'
from x \gexec
注意,string_agg()既用于分隔所有语句之间的联合,也用于将分隔的数据箭头粉碎为一个单元,以便传递到缓冲区。
\ gexec 将当前查询缓冲区发送到服务器,然后将查询输出的每一行的每一列(如果有的话)视为要执行的SQL语句。
我想从所有表的总数+表的列表与他们的计数。有点像绩效表,显示大部分时间都花在了哪里
WITH results AS (
SELECT nspname AS schemaname,relname,reltuples
FROM pg_class C
LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE
nspname NOT IN ('pg_catalog', 'information_schema') AND
relkind='r'
GROUP BY schemaname, relname, reltuples
)
SELECT * FROM results
UNION
SELECT 'all' AS schemaname, 'all' AS relname, SUM(reltuples) AS "reltuples" FROM results
ORDER BY reltuples DESC
当然,你也可以在这个版本的结果上加上一个LIMIT条款,这样你就可以得到最大的n个违例者以及总数。
需要注意的一点是,在大量进口后,您需要让它静置一段时间。我通过跨几个表向数据库中添加5000行(使用实际导入数据)来测试这一点。它显示了大约一分钟的1800条记录(可能是一个可配置的窗口)
这是基于https://stackoverflow.com/a/2611745/1548557的工作,所以感谢并认可在CTE中使用的查询
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
摘自我在GregSmith的回答中的评论,使其更具可读性:
with tbl as (
SELECT table_schema,table_name
FROM information_schema.tables
WHERE table_name not like 'pg_%' AND table_schema IN ('public')
)
SELECT
table_schema,
table_name,
(xpath('/row/c/text()',
query_to_xml(format('select count(*) AS c from %I.%I', table_schema, table_name),
false,
true,
'')))[1]::text::int AS rows_n
FROM tbl ORDER BY 3 DESC;
感谢@ a_horis_with_no_name
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.