Oracle Apps Technical Question: Download Questions PDF
What is count(*) from po_vendors(any table)? What does it do and
What is count(1) from po_vendors(any table)?
What is count(0) from po_vendors(any table)
the out put is same what is the difference?
Answer:
Result if count(*), count(1), count(0) will be same.
Howevenr,
When we use count(*) then
first oracle query executer gets all the rows in buffure
cache, including all column and then counts all the rows.
this will impact with less performance.
select count(1) or count(0)
This reduces unwanted I/O by selecting just '1' against all
the rows.
Best practice to getting rowcount of table is
select count(rowid) from table_name;
Howevenr,
When we use count(*) then
first oracle query executer gets all the rows in buffure
cache, including all column and then counts all the rows.
this will impact with less performance.
select count(1) or count(0)
This reduces unwanted I/O by selecting just '1' against all
the rows.
Best practice to getting rowcount of table is
select count(rowid) from table_name;
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