I've run into an interesting issue. A very long running transaction doing data loads is getting quite slow. I really don't want to break up the transactions (and for now it's ok), but it makes me wonder what exactly analyze counts.
Since dead, or yet to be visible tuples affect the plan that should be taken (until vacuum anyway) are these numbers reflected in the stats anywhere? Took an empty table, with a transaction I inserted a number of records and before comitting I ran analyze. Analyze obviously saw the table as empty, as the pg_statistic row for that relation doesn't exist. Commit, then analyze again and the values were taken into account. Certainly for large dataloads doing an analyze on the table after a substantial (non-comitted) change has taken place would be worth while for all elements involved. An index scan on the visible records may be faster, but on the actual tuples in the table a sequential scan might be best. Of course, for small transactions no-effect will be seen. But this may help with the huge dataloads, especially where triggers or constraints are in effect. -- Rod ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
