Re: JOINS and non use of indexes - Mailing list pgsql-sql

From Christopher Kings-Lynne
Subject Re: JOINS and non use of indexes
Date
Msg-id 003401c1df0a$523bead0$0200a8c0@SOL
Whole thread Raw
In response to JOINS and non use of indexes  ("Ian Cass" <ian.cass@mblox.com>)
List pgsql-sql
I haven't had a good look, but just remember that indexes on a table in
postgres are NOT inherited by its children.  You cannot define a unique
index over a column that is inherited - it will be unique for the table you
define it on only.  Hence, you may not actually have indexes on those
inherited tables, and therefore they cannot be used...

Chris

> Explain plan....
> Limit (cost=0.00..35.06 rows=5 width=620)
> -> Nested Loop (cost=0.00..30986063.51 rows=4418898 width=620)
> -> Append (cost=0.00..441.93 rows=111 width=496)
> -> Seq Scan on messages (cost=0.00..0.00 rows=1 width=496)
> -> Index Scan using messages_200203_ix2 on messages_200203 messages
> (cost=0.00..272.61 rows=68 width=383)
> -> Index Scan using messages_200204_ix2 on messages_200204 messages
> (cost=0.00..169.32 rows=42 width=384)
> -> Append (cost=0.00..180413.11 rows=7996912 width=124)
> -> Seq Scan on statusinds (cost=0.00..0.00 rows=1 width=124)
> -> Seq Scan on statusinds_200203 statusinds (cost=0.00..142835.73
> rows=6292073 width=71)
> -> Seq Scan on statusinds_200204 statusinds (cost=0.00..37577.38
> rows=1704838 width=65)
>
> (tables_YYYYMM are inherited)
>
> --
> Ian Cass
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
>



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