Quoting Christopher Kings-Lynne <[EMAIL PROTECTED]>: > > Another trick you can use with large data sets like this when you > want > > results > > back in seconds is to have regularly updated tables that aggregate > the data > > along each column normally aggregated against the main data set. > > > Maybe some bright person will prove me wrong by posting some > working > > information about how to get these apparently absent features > working. > > Most people just use simple triggers to maintain aggregate summary > tables...
Don't know if this is more appropriate to bizgres, but: What the first poster is talking about is what OLAP cubes do. For big aggregating systems (OLAP), triggers perform poorly, compared to messy hand-rolled code. You may have dozens of aggregates at various levels. Consider the effect of having each detail row cascade into twenty updates. It's particularly silly-looking when data is coming in as batches of thousands of rows in a single insert, e.g. COPY temp_table FROM STDIN; UPDATE fact_table ... FROM ... temp_table INSERT INTO fact_table ...FROM...temp_table (the above pair of operations is so common, Oracle added its "MERGE" operator for it). Hence my recent post (request) for using RULES to aggregate --- given no luck with triggers "FOR EACH STATEMENT". ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend