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

我喜欢Daniel Vérité的回答。 但是当你不能使用CREATE语句时,你可以使用bash解决方案,如果你是windows用户,可以使用powershell解决方案:

# You don't need this if you have pgpass.conf
$env:PGPASSWORD = "userpass"

# Get table list
$tables = & 'C:\Program Files\PostgreSQL\9.4\bin\psql.exe' -U user -w -d dbname -At -c "select table_name from information_schema.tables where table_type='BASE TABLE' AND table_schema='schema1'"

foreach ($table in $tables) {
    & 'C:\path_to_postresql\bin\psql.exe' -U root -w -d dbname -At -c "select '$table', count(*) from $table"
}

其他回答

我喜欢Daniel Vérité的回答。 但是当你不能使用CREATE语句时,你可以使用bash解决方案,如果你是windows用户,可以使用powershell解决方案:

# You don't need this if you have pgpass.conf
$env:PGPASSWORD = "userpass"

# Get table list
$tables = & 'C:\Program Files\PostgreSQL\9.4\bin\psql.exe' -U user -w -d dbname -At -c "select table_name from information_schema.tables where table_type='BASE TABLE' AND table_schema='schema1'"

foreach ($table in $tables) {
    & 'C:\path_to_postresql\bin\psql.exe' -U root -w -d dbname -At -c "select '$table', count(*) from $table"
}

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.

这对我很有效

SELECT schemaname,relname,n_live_tup FROM pg_stat_user_tables ORDER BY n_live_tup DESC;

我不记得我收集这个的URL了。但希望这能帮助到你:

CREATE TYPE table_count AS (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 
            c.relname
        FROM
            pg_catalog.pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
        WHERE 
            c.relkind = ''r''
            AND n.nspname = ''public'' 
        ORDER BY 1 
        LOOP
            FOR the_count IN EXECUTE ''SELECT COUNT(*) AS "count" FROM '' || t_name.relname 
            LOOP 
            END LOOP; 

            r.table_name := t_name.relname; 
            r.num_rows := the_count.count; 
            RETURN NEXT r; 
        END LOOP; 
        RETURN; 
END;
' LANGUAGE plpgsql; 

执行select count_em_all();应该得到所有表的行数。

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! !