> -----Original Message----- > From: Tom Lane [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, January 22, 2003 4:04 PM > To: Dann Corbit > Cc: Steve Crawford; [EMAIL PROTECTED]; > [EMAIL PROTECTED] > Subject: Re: [HACKERS] Terrible performance on wide selects > > > "Dann Corbit" <[EMAIL PROTECTED]> writes: > > Maybe I don't really understand the problem, but it seems simple > > enough to do it once for the whole query. > > We already do cache column offsets when they are fixed. The > code that's the problem executes when there's a > variable-width column in the table > --- which means that all columns to its right are not at > fixed offsets, and have to be scanned for separately in each > tuple, AFAICS.
Why not waste a bit of memory and make the row buffer the maximum possible length? E.g. for varchar(2000) allocate 2000 characters + size element and point to the start of that thing. If we have 64K rows, even at that it is a pittance. If someone designs 10,000 row tables, then it will allocate an annoyingly large block of memory, but bad designs are always going to cause a fuss. ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
