sql - PostgreSQL - Query optimization on SUM and LEFT JOIN -


i'm taking month using to_char() common in 2 tables namely table1 , table2.

but in table2 have both date , month.

also i've created index on table1. if write same query table1 results within 1000ms.

i'm taking sum of values , combining results using left join.

here's query.

 select     "month", -- table2     sum("value1"), -- table2     sum("value2") -- table1 table2 left join table1 on     table2."month" = to_char(table1.date, 'mon-yy') table2.date between '2014-01-01' , '2014-03-01' group "month"

explain of query :

 "groupaggregate  (cost=88133.61..3688425.12 rows=2 width=15)" "  ->  merge left join  (cost=88133.61..2707006.48 rows=130855816 width=15)" "        merge cond: (table2.month = (to_char((table1.date)::timestamp time zone, 'mon-yy'::text)))" "        ->  sort  (cost=8922.32..9056.34 rows=53609 width=11)" "              sort key: table2.month" "              ->  seq scan on table2(cost=0.00..3885.28 rows=53609 width=11)" "                    filter: ((date >= '2014-01-01'::date) , (date   materialize  (cost=79211.29..81652.22 rows=488186 width=8)" "              ->  sort  (cost=79211.29..80431.75 rows=488186 width=8)" "                    sort key: (to_char((table1.date)::timestamp time zone, 'mon-yy'::text))" "                    ->  seq scan on table1(cost=0.00..19735.86 rows=488186 width=8)"

currently have 500k rows in table1.

everyday update table around 3 4k records table1.

the query keeps running.

i no results.

can me i'm going wrong?

for query run 'efficiently', need 2 indexes. judging explain, table2 needs index on date column.

create index on table2 using btree(date);

table1 need computed index month name , day number e.g. "apr-14".

create index on table1 using btree(to_char(date, 'mon-yy'));

[edit, a_horse_with_no_name said not work because to_char not immutable - round writing own immutable function, simpler if stored date column!]

that said, text matching slower dates or numbers , if want order information alphabetical sort.


Comments

Post a Comment

Popular posts from this blog

apache - Remove .php and add trailing slash in url using htaccess not loading css -

i have add following code htaccess file removing .php extension , add trailing slash urls. worked fine reduced page loading speed , css code not loading @ all. pages ugly. please help rewriteengine on rewritebase / ## hide .php extension snippet # externally redirect /dir/foo.php /dir/foo rewritecond %{the_request} ^[a-z]{3,}\s([^.]+)\.php [nc] rewriterule ^ %1/ [r,l] # add trailing slash rewritecond %{request_filename} !-f rewritecond %{request_uri} !/$ rewriterule . %{request_uri}/ [l,r=301] # internally forward /dir/foo /dir/foo.php rewritecond %{request_filename} !-d rewritecond %{request_filename}.php -f rewriterule ^(.*?)/?$ $1.php [l] we can rewrite urls using .htaccess files. before writing in .htaccess files need verify kind of server using. can check server adding a <?php phpinfo(); ?> in php page. ensure mod_rewrite module enabled in apache server. can identified checking phpinfo included page. common methods used url rewriting follows ...
Read more

javascript - jQuery show full size image on click -

pretty self explanatory not workking . i want display full image when user click on image... yes know there tons of plugins but i want keep simple. any idea ? css : .full { display: none; width: 500px; height: 500px; margin-left: 100px; margin-top: -300px; position: fixed; background-color: #f00; z-index: 6; } .thumbnail { width: 50px; height: 50px; } html: <img class="thumbnail" src="http://4.bp.blogspot.com/-uhbdp2esxng/txneptvi92i/aaaaaaaaaky/upfqis7zto0/s1600/rihanna-wallpaper.jpg"> jquery: $(document).ready(function() { $('.thumbnail').on('click', function() { var img = $('<img />',{src:this.src,'class':'full'}); $('.full').html(img).show(); console.log('done!'); }); }); try looking how jquery works. $(document).ready(function() { $('.thumbnail').on('click', function(...
Read more