Re: [GENERAL] Special index for "like"-based query

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От Charles Clavadetscher
Тема Re: [GENERAL] Special index for "like"-based query
Дата
Msg-id 000801d2628f$e95569a0$bc003ce0$@swisspug.org
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Ответ на R: [GENERAL] Special index for "like"-based query  (Job <Job@colliniconsulting.it>)
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Hello

> -----Original Message-----
> From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Job
> Sent: Freitag, 30. Dezember 2016 11:42
> To: Francisco Olarte <folarte@peoplecall.com>
> Cc: David G. Johnston <david.g.johnston@gmail.com>; pgsql-general@postgresql.org
> Subject: R: [GENERAL] Special index for "like"-based query
>
> >>And, basically, if you need help with some queries you could try
> >>posting them whole, even redacted, along the table defs, this way
> >>perople can see the problem and not invent one based on a partial
> >>description
>
> Thank you very much, very kind from you.
>
> The index applied on the timestamp field is a btree("timestamp")
>
> The query is:
>
> select domain, sum(accessi) as c_count from TABLE where action='1' AND profile IN ('PROFILE_CODE') AND
> timestamp::date  BETWEEN '2016-12-27' AND '2016-12-30' AND timestamp::time BETWEEN '00:00:00' AND '23:59:59' GROUP
> BY domain ORDER BY c_count DESC  LIMIT 101
>
> The table format is:
>   Column   |           Type           |                                   Modifiers
> -----------+--------------------------+-----------------------------------------------------------------------------
> ---
>  id        | numeric(1000,1)          | not null default
> function_get_next_sequence('webtraffic_archive_id_seq'::text)
>  timestamp | timestamp with time zone |
>  domain    | character varying(255)   |
>  action    | character varying(5)     |
>  profile   | character varying        |
>  accessi   | bigint                   |
>  url       | text                     |
>
> Indexes:
>     "webtraffic_archive_day_2016_04_15_action_wbidx" btree (action)
>     "webtraffic_archive_day_2016_04_15_domain_wbidx" btree (domain)
>     "webtraffic_archive_day_2016_04_15_profile_wbidx" btree (profile) CLUSTER
>     "webtraffic_archive_day_2016_04_15_timestamp_wbidx" btree ("timestamp")

Is the index on timestamp used at all? The index on timestamp is built on timestamp, but you query using
timestamp::date.
You can check this using EXPLAIN.

Bye
Charles

>
> Last question: the table is partitioned. I need to manually create index for every sub-tables or there is a way to
> create on every sub-tables once?
>
> THANK YOU!
> /F
>
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