How long does it take to delete table fields in oracle database
The time to delete table fields depends on table size, structure, column type and database server performance. For small tables, deletion usually takes a few seconds; for medium-sized tables, it takes several minutes to tens of minutes; for large tables, it may take hours or even days. Methods to optimize performance include creating temporary tables, using TRUNCATE TABLE, dropping indexes and foreign keys, and using parallelism.
Oracle The time required to delete a table field
The time required to delete a table field depends on the following factors :
- Table size: The larger the table, the longer it takes to delete fields.
- Structure of the table: If the table has indexes or foreign key constraints, deleting fields may take longer.
- Column Types: Deleting large object type columns such as CLOB or BLOB may take longer.
- Database server performance: Hardware and software configuration will affect the speed of delete operations.
The following are some general guidelines that affect when to delete table fields:
- For small tables (Usually it takes a few seconds to delete a field.
- For medium-sized tables (1GB-10GB): It may take a few minutes to tens of minutes.
- For large tables (>10GB): It may take hours, or even days.
Optimize the performance of deleting table fields
In order to optimize the performance of deleting table fields, you can take the following measures:
- Create temporary table: Create a new temporary table that does not contain the fields to be deleted. Insert data from the original table into the new table, then delete the original table.
- Use TRUNCATE TABLE: TRUNCATE TABLE is faster than the DELETE statement because it does not record changes in the log. However, TRUNCATE TABLE deletes all data, so use it with caution.
- Delete indexes and foreign keys: Before deleting table fields, delete the relevant indexes and foreign keys, and then re-create them.
- Using parallelism: If the database server supports parallelism, you can use parallel DML statements to perform delete operations in parallel.
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