How are tables deleted but database size does not change?
20GB Tables are deleted in my database but database size does not change and disk size showing same size. When you create a database and assign it gigabytes of space based on a capacity planning that space is kind of a reserved space.
Why does SQL Server database size never decrease?
In an ideal world – you’d create your DB with plenty of free space to grow into. I call this “Right Sizing” your database. You would allow this free space to be there and not strive to give it back and keep your total size right at your used size.. Why? Because your database will eventually grow again.. Then you’ll shrink again..
How to reduce the size of ibdata1 in MySQL?
MySQL doesn’t reduce the size of ibdata1. Ever. Even if you use optimize table to free the space used from deleted records, it will reuse it later. An alternative is to configure the server to use innodb_file_per_table, but this will require a backup, drop database and restore.
How does deleting rows in a database decrease file size?
Deleting rows in a database will not decrease the actual database file size. You need to compact the database after row deletion. After running this, you’ll want to rebuild indexes. Shrinking typically causes index fragmentation, and that could be a significant performance cost.
When do you gain space by deleting data from a table?
When I deducted (subtracted) the difference in the Reserved (KB) (Difference before and after data deletion) field from the Total of space gained from the data deletion is equal to the Unused (KB) gained field value. I am not a SQL expert and not questioning but trying to understand whether we really gain space by deleting data from the tables.
How to delete all rows in table based on another table?
There is no solution in ANSI SQL to use joins in deletes, AFAIK. Other solution (sometimes performing faster): PostgreSQL implementation would be: This will delete all rows in Table1 that match the criteria: Oftentimes, one wants to delete some records from a table based on criteria in another table.
What happens when you delete data in Oracle?
When you deleted the data, space was freed up in the blocks. That space is now available for subsequent inserts (or updates) in the table you deleted data from. That’s normally sufficient because the table will normally grow again in the future.
How does the size of a database change?
When you create a database and assign it gigabytes of space based on a capacity planning that space is kind of a reserved space. The database should grow internally when records are inserted and you will find that internal free space is reduced as records are inserted, but the database keeps the same reserved space.
What happens when you delete data from a database?
When you delete records, then you see that internal free space increased, but the same reserved space. If you want to shrink the reserved space of the database when you delete data and then the reserved space needs to be increased later as data is inserted again then this procedure may create physical disk fragmentation and affect performance.