如何使用psql客户端执行查询结果？

Question

Using the psql client version 8.4.20, I created this select command that generates a bunch of other select commands:

mydatabase=# select concat('select count(*) from ', table_schema, '.', table_name, ';') from information_schema.tables where table_name like '%stockindex_alias%';

select count(*) from de_de.merged_stockindex_alias_de_de;
select count(*) from en_us.merged_stockindex_alias_en_us;
select count(*) from es_la.merged_stockindex_alias_es_la;
select count(*) from fr_fr.merged_stockindex_alias_fr_fr;
select count(*) from nl_nl.merged_stockindex_alias_nl_nl;
select count(*) from pt_br.merged_stockindex_alias_pt_br;
select count(*) from zh_hk.merged_stockindex_alias_zh_hk;

I know I can use \\g to store those seven statements into a file, then execute the file with \\i.

How can I execute the result of the query (those seven statements) in a single command without the intermediate file? I've tried \\set, EXECUTE, searched the web, but can't get it right.

EDIT: The previous select statements erroneously had the word "table" in them, which I have fixed.

Answer 1

I don't know if it works in 8.4; it works in 9.2.

DO $$
DECLARE
    x text;
BEGIN
    FOR x IN (select concat('select count(*) from ', table_schema, '.', table_name, ';') from information_schema.tables where table_name like '%stockindex_alias%' LOOP
        EXECUTE x;
    END LOOP;
END;
$$;

Basically you create an anonymous function block and execute it. Function blocks (or whatever the correct name is) allow for variable declaration and dynamic execution.

Answer 2

If you can get by with an approximate count, you can use the system catalogs:

SELECT s.nspname AS locale, c.reltuples AS count
FROM pg_class c
JOIN pg_namespace s ON s.oid = c.relnamespace
WHERE c.relname LIKE '%stockindex_alias%';

This will be most accurate immediately after a VACUUM ANALYZE (assuming you are a superuser or own all the affected tables) and gradually reducing in accuracy as the affected tables are modified.