Inline Stats are statistics collected in between a script, usually before a SELECT or a JOIN.
It is mostly used to over-ride the optimiser to pick a different PLAN.
For example:
We have a table FACT_SALES with PI on CUS_ID.
But, the Sales_Dimension has to be joined on PROD_ID, a primary key in the Dimension. There is no point joining based on CUS_ID, as it will lead to a spool-join rather than amp-local join.
So, we collect an Inline Stats by using:
Collects stats on Sales_Dim column PROD_ID;
This will help the optimizer to join the 2 tables based on PROD_ID.
It is mostly used to over-ride the optimiser to pick a different PLAN.
For example:
We have a table FACT_SALES with PI on CUS_ID.
But, the Sales_Dimension has to be joined on PROD_ID, a primary key in the Dimension. There is no point joining based on CUS_ID, as it will lead to a spool-join rather than amp-local join.
So, we collect an Inline Stats by using:
Collects stats on Sales_Dim column PROD_ID;
This will help the optimizer to join the 2 tables based on PROD_ID.
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