Oracle SQL Self Join advice -

-

this first question on forum, patient... question efficient way build query on following table:

create table opentrades(     accountnumber   number,     snapshottime    date,     ticket      number,     opentime    date,     tradetype   varchar2(4),     tradesize   number,     tradeitem   char(6),     openprice   number,     tradesl     number,     tradetp     number,     tradeswap   number,     tradeprofit number   );  alter table opentrades add constraint opentrades_pk primary key (accountnumber, snapshottime, ticket) using index tablespace mynnidx;`

this table populated every 15 minutes, , timestamp of insert saved in snapshottime column. sought query should group records week number (based on snapshottime), , filter records return latest (snapshottime) within same week.

so far, i've tried following:

select myweekno(ot1.snapshottime), max(ot2.snapshottime) opentrades ot1, opentrades ot2 myweekno(ot2.snapshottime)=myweekno(ot1.snapshottime) group myweekno(ot1.snapshottime);.

( note: myweekno() modified version of to_char(,'iw'). )

however, takes way longer expected (15 minutes less 1500 rows); i'm sure there's better way write this, far, has eluded me. idea?

you don't need self-join @ all. you'll same result just:

select myweekno(ot.snapshottime), max(ot.snapshottime) opentrades ot group myweekno(ot.snapshottime);

you may find useful add virtual column holding calculated week number, won't have performance impact query, , wouldn't benefit indexing either. no filter you'd need full table scan anyway, unless calculated value , snapshottime indexed, , may not desirable.

your question suggests might want other data latest rows in each grouped week, , have multiple rows per snapshot. might explain self-join approach: you're trying find latest snapshot date in each week , plan join find rows snapshot dates? though may misinterpreting that. if trying though, can use analytic function assign ranking each row based on snapshot date , week number, , filter see ranked first:

select weekno, snapshottime, accountnumber -- , other columns (   select ot.*, myweekno(ot.snapshottime) weekno,     rank() on (partition myweekno(ot.snapshottime)       order ot.snapshottime desc) ranking   opentrades ot ) ranking = 1 order weekno, accountnumber, ticket;

sql fiddle demo.

if 'snapshot' can contain dates spanning period of, say, 10 minutes, use alternative analytic approach records in latest load:

select weekno, snapshottime, accountnumber, ticket (   select ot.*, myweekno(ot.snapshottime) weekno,     max(snapshottime) on (partition myweekno(ot.snapshottime)) latestend   opentrades ot ) snapshottime > latestend - interval '10' minute  , snapshottime <= latestend order weekno, accountnumber, ticket;

here latestend inner query last snapshottime week, , filter ignores isn't between time , ten minutes before it.

sql fiddle showing 5 records recent load selected, , preceding load skipped.


Comments

Post a Comment

Popular posts from this blog

database - VFP Grid + SQL server 2008 - grid not showing correctly -

-
i having problem, have grid called "gridbasica" , this: thisform.gridbase.recordsource = "sgviemp" sgviemp cursor made executing select sqlserver command sqlexec. when want modify registry, go form , the update there. so, when come form grid, grid isnt grid anymore, big white rectangle. reading around said: delete recordsource , asingt again. thisform.gridbase.recordsource = "" *--i sqlexe here thisform.gridbase.recordsource = "sgviemp" i , works, but, when click button modify again cursos updated modify form doesnt load fields did first time. could me out that? thanks in advance. --------------- edit ------------------ i have been doing recommended: lnselect = select(0) n = sqlexec(thisform.conexion,"select emp_ccodigo codigo, emp_cnombre 'nombre o razon social', emp_cnumrif 'r.i.f' sgviempr","sgviemp1") set echo on suspend select sgviemp zap in sgviemp *-- browse *--zaps correct
Read more

jquery - Set jPicker field to empty value -

-
im using jpicker color selector in form. have clear value set window/icon 'no color selected' state. i've tried following: $(':input[name="color"]').val(''); //access value directly. (does not affect jpicker) 2: $.jpicker.list[0].color.active.val('hex', '', this); //set color black , input value 000000, instead of empty string 3: $.jpicker.list[0].color.active.val(null, '', this); //does nothing none of 3 methods seems behave properly. in advance. this works me :) $.jpicker.list[0].color.active.val('v', null); here example: http://jsfiddle.net/3up7n/
Read more

.htaccess - htaccess convert request to clean url and add slash at the end of the url -

-
ok , searched more 4 days , more 20 posts here in stach or in websites without kind of success first here htaccess file rewriteengine on rewriterule ^([a-za-z0-9_]+)/?$ index.php?page=$1 [nc] rewriterule ^([a-za-z0-9_]+)\/([a-za-z0-9_]+)\/?$ index.php?page=$1&action=$2 [nc] i tried many codes 1 worked me can call request , works me www.example.com/pagename => www.example.com/index.php?page=pagename here questions , please provide me information "in detail" understand code well 1- how convert request automatically www.example.com/index.php?page=pagename www.example.com/pagename 2- if tried add slash @ end shows me page without images or styling mean www.example.com/pagename => works www.example.com/pagename/ => doesn't work that's :) for first part need 301 rule this: rewritecond %{the_request} /index\.php\?page=([^\s&]+) [nc] rewriterule ^ /%1? [r=301,l] for second part use absolute path in css, js, images files r
Read more