David, * david@xxxxxxx (david@xxxxxxx) wrote: > I am working with the rsyslog developers to improve it's performance in > inserting log messages to databases. Great! > currently they have a postgres interface that works like all the other > ones, where rsyslog formats an insert statement, passes that the the > interface module, that sends it to postgres (yes, each log as a seperate > transaction) Ouch. > the big win is going to be in changing the core of rsyslog so that it can > process multiple messages at a time (bundling them into a single > transaction) Yup. > 1. begin; insert; insert;...;end Doing the insert in a transaction should definitely improve your performance. Doing them as prepared statements would be good too, and using binary mode would very likely help. > 2. insert into table values (),(),(),() Using this structure would be more database agnostic, but won't perform as well as the COPY options I don't believe. It might be interesting to do a large "insert into table values (),(),()" as a prepared statement, but then you'd have to have different sizes for each different number of items you want inserted. > 3. copy from stdin > (how do you tell it how many records to read from stdin, or that you > have given it everything without disconnecting) Assuming you're using libpq, you just call PQputCopyEnd(). Then you call PQgetResult() to check that everything worked ok. > 4. copy from stdin in binary mode Binary mode, in general, should be faster. You should consider what format the data is inside your application though (it's less useful to use binary copy if you're having to convert from text to binary in your application). > and each of the options above can be done with prepared statements, > stored procedures, or functions. > > I know that using procedures or functions can let you do fancy things > like inserting the row(s) into the appropriate section of a partitioned > table We would normally recommend having the database handle the partitioning by using a trigger on the base table to call a stored procedure. The application really doesn't need to know about this. > other than this sort of capability, what sort of differences should be > expected between the various approaches (including prepared statements vs > unprepared) > > since the changes that rsyslog is making will affect all the other > database interfaces as well, any comments about big wins or things to > avoid for other databases would be appriciated. Hope this helps. Thanks, Stephen
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