> On Jun 1, 2020, at 7:03 AM, Julien Rouhaud <rjuju123@xxxxxxxxx> wrote: > > On Mon, Jun 1, 2020 at 12:48 PM Achilleas Mantzios > <achill@xxxxxxxxxxxxxxxxxxxxx> wrote: >> >> On 1/6/20 1:36 μ.μ., Julien Rouhaud wrote: >>> On Mon, Jun 1, 2020 at 12:02 PM Achilleas Mantzios >>> <achill@xxxxxxxxxxxxxxxxxxxxx> wrote: >>> Because read only transaction usually don't consume an xid. So yes >>> pg_stat_database gives a more reasonable approximation of the real >>> number of transactions happening on the server. >> Thank you, so what would be the official way to monitor txid consumption (from a MVCC / Freezing admin POV)? > > I'm not sure what you're really looking for. If it's the txid > consumption rate, you can use txid_current() at regular interval to > compute it (note that this function will consume a txid). For object > freeeze, you can use age(datfrozenxid) from pg_database, or > age(relfrozenxid) from pg_class. > > I also record the stats tables every minute by either inserting into a table hist_ table or exporting the data out to be inserted into another table. When exporting the pg_stat_database table I added the following to record the information without the need to call txid_current(): coalesce(txid_current_if_assigned(), txid_snapshot_xmax(txid_current_snapshot())) as xact_txid, …
