Thread: Support for bulk reads/writes ?
I have looked around quite a bit and could not find any information on whether or not Postgres supports Oracle-style array usage for bulk reading/writing of the database, e.g. bulk insert statements ? I have a web application --- I'm acquiring/calculating various data throughout a user's session that needs to be written to the database. I could either just insert/update the data in Postgres as it is computed throughout the session, or, I could keep the data in memory (using servlets, storing the data at session scope) and then write it all to Postgres when the session ends, if there were any advantage to doing so, i.e., if there were a way that I could insert the data in bulk to save a bunch of trips back and forth to the database. Otherwise, there would seem to be no performance difference in whether the web app is executing a bunch of SQL statements over the course of the session vs. executing all the same statements at the end of the session. The web application could experience high loads, in terms of the number of simultaneous user sessions, which is why I'm concerned about performance. thanks, charlie
I'm not entirely sure if I'm understanding you, but if I am then it seems like transactions would do what you're asking, but batch them at the backend point rather than the client point: BEGIN; INSERT... INSERT... INSERT... COMMIT; will wait until the COMMIT line to actually change the backend db. ---------------------------------------------------------------------- Andrew J Perrin - andrew_perrin@unc.edu - http://www.unc.edu/~aperrinAssistant Professor of Sociology, U of North Carolina,Chapel Hill 269 Hamilton Hall, CB#3210, Chapel Hill, NC 27599-3210 USA On Mon, 11 Feb 2002, charlie wrote: > I have looked around quite a bit and could not find any information on > whether or not Postgres supports Oracle-style array usage for bulk > reading/writing of the database, e.g. bulk insert statements ? > > I have a web application --- I'm acquiring/calculating various data > throughout a user's session that needs to be written to the database. I > could either just insert/update the data in Postgres as it is computed > throughout the session, or, I could keep the data in memory (using servlets, > storing the data at session scope) and then write it all to Postgres when > the session ends, if there were any advantage to doing so, i.e., if there > were a way that I could insert the data in bulk to save a bunch of trips > back and forth to the database. Otherwise, there would seem to be no > performance difference in whether the web app is executing a bunch of SQL > statements over the course of the session vs. executing all the same > statements at the end of the session. > > The web application could experience high loads, in terms of the > number of simultaneous user sessions, which is why I'm concerned about > performance. > > thanks, > charlie > > > ---------------------------(end of broadcast)--------------------------- > TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) >
You may find these code snippets handy
CREATE FUNCTION editpresentationparam(int,text[][])
RETURNS int
AS 'DECLARE prid ALIAS FOR $1; pairs ALIAS FOR $2; result int; rc int; i int;
BEGIN result := 0; i := 1; DELETE FROM tblPresentationParam WHERE ppprID = prid; WHILE
pairs[i][1]!= '''' LOOP INSERT INTO tblPresentationParam (ppprID,pppnID,ppValue) SELECT prid,
pnID,pairs[i][2] FROM
tblPresentationParamName WHERE pnName = pairs[i][1]; GET DIAGNOSTICS rc = ROW_COUNT; result :=
result+ rc; i := i + 1; END LOOP; RETURN result; END;'
LANGUAGE 'plpgsql';
<?php
//Turns a pair of values into a postgres array literal
//EG: "name","Bloggs, Bill 'owdy" ->
// '{"name","Bloggs, Bill ''owdy"}'
function makepair($p1,$p2) { $pat = array ("/\\\\/","/\"/","/'/"); $rep = array ( '\\\\' , '\"' ,"''"); return
'{"'.preg_replace($pat,$rep,$p1). '","'. preg_replace($pat,$rep,$p2).'"}';
}
function updatepresentationparam($formvars) { if(isset($formvars['ref'])&&preg_match('/^\d+$/',($formvars['ref']))) {
$q="SELECT editpresentationparam(".$formvars['ref'].",'{"; reset($formvars); while (list($pnname,$ppvalue) =
each($formvars)){ if($pnname != "ref" && $pnname != "func" && $ppvalue != "") {
$q.=makepair($pnname,$ppvalue).","; } } $q.="{,}}')"; if(! ($res=psql_query_wrap($q))) { return -1;
} else { $row = pg_fetch_array($res,0); return $row[0]; } } else return -1;
}
?>
==============================
David Stanaway
Personal: david@stanaway.net
Work: david@netventures.com.au