Databases
StackOverflow2013
Postsdbo
POPostgresql Query very slow with ::date, ::time, and interval
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POPostgresql Query very slow with ::date, ::time, and interval
    primarykey
    data
    text
    <p>I have a sql query that is very slow:</p> <pre><code> select number1 from mytable where symbol = 25 and timeframe = 1 and date::date = '2008-02-05' and date::time='10:40:00' + INTERVAL '30 minutes' </code></pre> <p>The goal is to return one value, and postgresql takes 1.7 seconds to return the desired value(always a single value). I need to execute hundreds of those queries for one task, so this gets extremely slow. Executing the same query, but pointing to the time directly without using interval and ::date, ::time takes only 17ms:</p> <pre><code> select number1 from mytable where symbol = 25 and timeframe = 1 and date = '2008-02-05 11:10:00' </code></pre> <p>I thought it would be faster if I would not use ::date and ::time, but when I execute a query like:</p> <pre><code> select number1 from mytable where symbol = 25 and timeframe = 1 and date = '2008-02-05 10:40:00' + interval '30 minutes' </code></pre> <p>I get a sql error (22007). I've experimented with different variations but I couldn't get interval to work without using ::date and ::time. Date/Time Functions on postgresql.org didn't help me out.</p> <p>The table got a multi column index on symbol, timeframe, date.</p> <p>Is there a fast way to execute the query with adding time, or a working syntax with interval where I do not have to use ::date and ::time? Or do I need to have a special index when using queries like these? </p> <p>Postgresql version is 9.2.</p> <p>Edit: The format of the table is: date = timestamp with time zone, symbol, timeframe = numeric.</p> <p>Edit 2: Using</p> <pre><code>select open from ohlc_dukascopy_bid where symbol = 25 and timeframe = 1 and date = timestamp '2008-02-05 10:40:00' + interval '30' minute </code></pre> <p>Explain shows:</p> <pre> "Index Scan using mcbidindex on mytable (cost=0.00..116.03 rows=1 width=7)" " Index Cond: ((symbol = 25) AND (timeframe = 1) AND (date = '2008-02-05 11:10:00'::timestamp without time zone))" </pre> <p>Time is now considerably faster: 86ms on first run.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USa_horse_with_no_name
    1. USharbun
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COAnd please post the full error message, not only the error number.
      singulars
      1. POPostgresql Query very slow with ::date, ::time, and interval
      1. USa_horse_with_no_name
    2. COI only have an multi column index on symbol, timeframe, date. would an extra index exclusively for date make sense? I thought the multi column index would be enough. Edit: I see I should run a explain to see if my index is being used.
      singulars
      1. POPostgresql Query very slow with ::date, ::time, and interval
      1. USharbun
    3. COdepends on how the index is defined. Which column is first in the index? Please post the full table definition including indexes and the execution plan
      singulars
      1. POPostgresql Query very slow with ::date, ::time, and interval
      1. USa_horse_with_no_name
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload