sakthikumar
asked on
Optimization and Soft parse?
Dear Experts,
I am seeing different anwers for Soft parse,
If the query is already available in library cache, a new plan will be created or any previously created plan for the same sql will be used.
I am seeing different anwers for Soft parse,
If the query is already available in library cache, a new plan will be created or any previously created plan for the same sql will be used.
Gerwin Jansen
http://docs.oracle.com/cd/B16240_01/doc/doc.102/e16282/oracle_database_help/oracle_database_instance_throughput_softparse_pct.html
ASKER
This is fine, You know there are many steps in processing the sqls before result is given to client.
like semantic checks , syntactic checks, plan generation .. etc.,
which of these will be eliminated for a soft parse?
like semantic checks , syntactic checks, plan generation .. etc.,
which of these will be eliminated for a soft parse?
the steps you mention are those involved in a hard parse.
soft parse, as noted in the first post, is the act of looking of a previously hard parsed statement and using that plan (which means the semantic checks, syntax checks, plan generation, etc have already been completed) so all of them will be eliminated in a hard parse
soft parse is a lightweight operation, but still non-zero resource consumption.
soft parse, as noted in the first post, is the act of looking of a previously hard parsed statement and using that plan (which means the semantic checks, syntax checks, plan generation, etc have already been completed) so all of them will be eliminated in a hard parse
soft parse is a lightweight operation, but still non-zero resource consumption.
There is still some parsing done, e.g. to eliminate changed literals. E.g.
select * from tbl1 where a = '1';
and
select * from tbl1 where a = '2';
can still use the same plan. An exact comparison would not find a match. But that part is tried to a low level degree only, otherwise the effort needed would be near having to perform a hard parse (with cached meta data).
select * from tbl1 where a = '1';
and
select * from tbl1 where a = '2';
can still use the same plan. An exact comparison would not find a match. But that part is tried to a low level degree only, otherwise the effort needed would be near having to perform a hard parse (with cached meta data).
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