Problem With Query Execution Time - No_merge Hints. Slow Parse of Complex Statement in 12.2 (Doc ID 2489090.1)

Last updated on DECEMBER 28, 2020

Applies to:

Symptoms

Scripts:

1. Prepare_tables.sql
a. Create source table
b. Create target table
c. Insert with example row to source table
2. SQL_1.sql:
a. Create table as select
3. SQL_2.sql:
a. Insert as select

When we run SQL_1.sql then the parsing time (hard_parse) is about 10 sec.
When we run SQL_2.sql then the parsing time (hard_parse) is about 10 min.

The queries are created by the code generator - hence the large size.

Since the SQL parsing time is about 10 seconds, why insert as select takes 10 minutes. Is not it a bug?

Cause

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