Re: [PERFORM] Column order performance
Josh Berkus wrote: Does the order of columns of varying size have any effect on SELECT/INSERT/UPDATE/and/or/DELETE performance? Take the example where an integer primary key is listed first in the table and alternatively listed after some large varchar or text columns? No, the order of the columns in the table makes no difference. They are not physically stored in the metadata order, anyway; on the data pages, fixed-length fields (e.g. INT, BOOLEAN, etc.) are stored first and variable-length fields (CHAR, TEXT, NUMERIC) after them, AFAIK. Is this true even after a table is altered to append say, an integer column, after there are already variable-length columns in the table? -Bill ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] Column order performance
Bill, Does the order of columns of varying size have any effect on SELECT/INSERT/UPDATE/and/or/DELETE performance? Take the example where an integer primary key is listed first in the table and alternatively listed after some large varchar or text columns? No, the order of the columns in the table makes no difference. They are not physically stored in the metadata order, anyway; on the data pages, fixed-length fields (e.g. INT, BOOLEAN, etc.) are stored first and variable-length fields (CHAR, TEXT, NUMERIC) after them, AFAIK. The only thing I have seen elusive reports of is that *display* speed can be afffected by column order (e.g. when you call the query to the command line with many rows) but I've not seen this proven in a test case. -- Josh Berkus Aglio Database Solutions San Francisco ---(end of broadcast)--- TIP 7: don't forget to increase your free space map settings
