Re: [GENERAL] a JOIN to a VIEW seems slow
| От | Frank Millman |
|---|---|
| Тема | Re: [GENERAL] a JOIN to a VIEW seems slow |
| Дата | |
| Msg-id | 3BBA6BBA6D3A48AEB98F1E850D2987C7@FrankLaptop обсуждение исходный текст |
| Ответ на | [GENERAL] a JOIN to a VIEW seems slow ("Frank Millman" <frank@chagford.com>) |
| Список | pgsql-general |
Frank Millman wrote:
>
> On Thu, Sep 21, 2017 at 3:54 PM, Merlin Moncure wrote:
> > Something is not adding up here. Can you EXPLAIN ANALYZE the 26 minute
> > query?
> > query?
> Here it is -
>
>
There is one thing I have not mentioned. I am pretty sure it has no effect on the outcome, but just in case, here it is.
The underlying physical tables, ‘ar_tran_inv’, ‘ar_tran_crn’, and ‘ar_tran_rec’, have this index declared -
CREATE UNIQUE INDEX _ar_tran_inv ON ar_tran_inv (tran_number) WHERE deleted_id = 0;
and similar for the other two tables.
I have not included the column ‘deleted_id’ in the VIEW ‘ar_trans’, so I cannot add ‘WHERE deleted_id = 0’ to any queries.
This could mean a slow result if sorting by ‘tran_number’ or joining on ‘tran_number’.
However, as this particular query joins on ‘tran_type’ (a literal string) and ‘tran_row_id’ (the primary key to the underlying table), I don’t think it causes a problem.
[UPDATE] I actually tried adding ‘deleted_id’ to the VIEW, and including it in the WHERE clause, but the timings did not improve.
Frank
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