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Hi folks; I am trying to continue profiling which in turn feeds query and index tuning changes for the AKCS-WWW forum software, and appear to have no good way to do what I need to do -- or I've missed something obvious. The application uses the libpq interface from "C" to talk to Postgres which contains all the back end data. Since this is a forum application it is very read-heavy (other than accounting and of course user posting functionality), and is template-driven. All of the table lookup functions that come from the display templates are compartmentalized in one function in the base code. What I want to be able to do is to determine the resource usage by Postgres for each of these calls. I can do this by adding a call into the function just before the "real" call to PQexec() that prepends "explain analyze" to the call, makes a preamble call to PQexec() then grabs the last tuple returned which is the total execution time (with some text), parse that and there is the total time anyway. But I see no way to get stats on I/O (e.g. Postgres buffer hits and misses, calls to the I/O operating system level APIs, etc.) But while I can get the numbers this way it comes at the expense of doubling the Postgres processing. There does not appear, however, to be any exposition of the processing time requirements for actual (as opposed to "modeled" via explain analyze) execution of queries -- at least not via the libpq interface. Am I missing something here -- is there a way to get resource consumption from actual queries as they're run? What I'm doing right now is the above, with a configuration switch that has a minimum reportable execution time and then logging the returns that exceed that time, logging the queries that have the above-threshold runtimes for analysis and attempted optimization. This works but obviously is something one only does for profiling as it doubles database load and is undesirable in ordinary operation. What I'd like to be able to do is have the code track performance all the time and raise alerts when it sees "outliers" giving me a continually-improving set of targets for reduction of resource consumption (up until I reach the point where I don't seem to be able to make it any faster of course :-)) Thanks in advance! |
