HWM Reset and Compression
Hi Oracle Gurus,
I need some information on HWM and compression.
As per my understanding HWM reset would be primarily done for couple of reasons.
1. Reduced the table size. i.e if the actual size(actual_num_rows*avg_row_len) of the table is 10G and if the in dba_segments it says 20G; then we can save approx 10G on resetting the HWM.
2. Performance Improvement; This will make sure that the empty blocks are not read from the disks. i.e the all the blocks are completely filled with the table's details and there is no need for any FTS operation to go through the empty blocks as well.
I need some information on HWM and compression.
As per my understanding HWM reset would be primarily done for couple of reasons.
1. Reduced the table size. i.e if the actual size(actual_num_rows*avg_row_len) of the table is 10G and if the in dba_segments it says 20G; then we can save approx 10G on resetting the HWM.
2. Performance Improvement; This will make sure that the empty blocks are not read from the disks. i.e the all the blocks are completely filled with the table's details and there is no need for any FTS operation to go through the empty blocks as well.
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