取回索引信息的PostgreSQL 8.4

Question

我需要获取对特定表有关指数的以下信息：

• 索引名被索引
• 独特或不
• 列？

如何在PostgreSQL 8.4中做到这一点？

注意：我必须能够用PHP调用这个东西。只是说...

编辑：我第一次有这样的查询，但它仅适用起始PostgreSQL的9.0：

SELECT t.relname AS table_name, 
relname AS index_name, 
a.attname AS column_name, 
ix.indisunique 
FROM pg_class t, 
pg_class i, 
pg_index ix, 
pg_attribute a, 
pg_constraint c 
WHERE t.oid = ix.indrelid 
    AND i.oid = ix.indexrelid 
    AND a.attrelid = t.oid 
    AND i.oid = c.conindid 
    AND a.attnum = ANY(ix.indkey) 
    AND c.contype != 'p' 
    AND t.relkind = 'r' 
    AND t.relname = 'tablename' 
ORDER BY t.relname, i.relname 

Answer 1

你可以简单地使用pg_indexes，其中将包括完整的CREATE TABLE语句（和因此有关列和唯一性的信息）。

或者，下面应该工作：

select t.relname as table_name, 
     ix.relname as index_name, 
     array_to_string(array_agg(col.attname), ',') as index_columns, 
     i.indisunique 
from pg_index i 
    join pg_class ix on ix.oid = i.indexrelid 
    join pg_class t on t.oid = i.indrelid 
    join (select ic.indexrelid, 
       unnest(ic.indkey) as colnum 
     from pg_index ic) icols on icols.indexrelid = i.indexrelid 
    join pg_attribute col on col.attrelid = t.oid and col.attnum = icols.colnum 
where t.relname = 'tablename' 
group by t.relname, ix.relname, i.indisunique 
order by t.relname, 
     ix.relname 

它不以正确的顺序返回列虽然。但我没有时间深入研究。