The moment after LOAD has been exchanged with Q2 there will be no synopsis on Q2; it won’t have been created yet.
Incremental statistics requires synopses to update the global-level statistics for SALES efficiently so a synopsis for Q2 will be created automatically when statistics on SALES are gathered.
No login sex chat rightnow Male sex chat jobs
It’s common to see it used in decision support systems and large operational data stores.
Make sure you’ve taken a look at Part 1, or you are at least familiar with the concept of incremental statistics so that you know what a synopsis is in the context of a partitioned table.
This happens even if you don't choose to seed column usage.
Oracle Database 12c includes an enhancement that allows you to create a synopsis on LOAD prior to the exchange.
This is how to prepare the LOAD table before the exchange: Q2 will have fresh statistics and a synopsis as soon as the exchange completes. Statistics on Q2 will be gathered again after the exchange (when statistics are gathered on SALES) unless you have created appropriate histograms and extended statistics on LOAD before the exchange.
The list_script in Git Hub displays extended statistics and histograms for a particular table if you want to take a look at what you have.
For example, new data can be inserted into LOAD before any indexes have been created on this table.
If the volume of data is large, creating indexes at the end of the load is very efficient and avoids the need to bear the higher cost of index maintenance during the load.
There is nevertheless a scenario where you might want to gather statistics on LOAD prior to the exchange.
For example, if it’s likely that Q2 will be queried before statistics have been gathered on SALES then you might want to be sure that statistics are available on Q2 as soon as the exchange completes.
The performance benefit is especially impessive if data is loaded at very high rates in parallel.