未索引外键

未索引外键

管理片段

未索引外键

适用于 PostgreSQL

… – 9.2

编写语言

SQL

依赖

无

我不确定此查询的原始来源，但它可能来自 2007 年 pgsql-performance 邮件列表中的 Michael Fuhr。

它在几个方面进行了修改

• 添加了引用表和被引用表的尺寸，
• 添加索引建议，
• 仅搜索单列或复合索引，其中前导列是引用键。

在 PostgreSQL 9.2 中测试（可能适用于早期版本）。

CREATE OR REPLACE VIEW admin.unindexed_foreign_keys AS
WITH y AS (
    SELECT
        pg_catalog.format('%I.%I', n1.nspname, c1.relname)  AS referencing_tbl,
        pg_catalog.quote_ident(a1.attname) AS referencing_column,
        t.conname AS existing_fk_on_referencing_tbl,
        pg_catalog.format('%I.%I', n2.nspname, c2.relname) AS referenced_tbl,
        pg_catalog.quote_ident(a2.attname) AS referenced_column,
        pg_relation_size( pg_catalog.format('%I.%I', n1.nspname, c1.relname) ) AS referencing_tbl_bytes,
        pg_relation_size( pg_catalog.format('%I.%I', n2.nspname, c2.relname) ) AS referenced_tbl_bytes,
        pg_catalog.format($$CREATE INDEX ON %I.%I(%I);$$, n1.nspname, c1.relname, a1.attname) AS suggestion
    FROM pg_catalog.pg_constraint t
    JOIN pg_catalog.pg_attribute  a1 ON a1.attrelid = t.conrelid AND a1.attnum = t.conkey[1]
    JOIN pg_catalog.pg_class      c1 ON c1.oid = t.conrelid
    JOIN pg_catalog.pg_namespace  n1 ON n1.oid = c1.relnamespace
    JOIN pg_catalog.pg_class      c2 ON c2.oid = t.confrelid
    JOIN pg_catalog.pg_namespace  n2 ON n2.oid = c2.relnamespace
    JOIN pg_catalog.pg_attribute  a2 ON a2.attrelid = t.confrelid AND a2.attnum = t.confkey[1]
    WHERE t.contype = 'f'
    AND NOT EXISTS (
        SELECT 1
        FROM pg_catalog.pg_index i
        WHERE i.indrelid = t.conrelid
        AND i.indkey[0] = t.conkey[1]
    )
)
SELECT  referencing_tbl,
        referencing_column,
        existing_fk_on_referencing_tbl,
        referenced_tbl,
        referenced_column,
        pg_size_pretty(referencing_tbl_bytes) AS referencing_tbl_size,
        pg_size_pretty(referenced_tbl_bytes) AS referenced_tbl_size,
        suggestion
FROM y
ORDER BY
    referencing_tbl_bytes DESC,
    referenced_tbl_bytes DESC,
    referencing_tbl,
    referenced_tbl,
    referencing_column,
    referenced_column;