Originally from the User Slack
@Saif_AliSaif_Ali**:** Hi everyone, I’m working with ScyllaDB and had a design/operations question:
I’m currently writing data with a TTL of 90 days at insert time. Now I have a use case where I need to extend the TTL of all existing data by another 90 days.
• Is there a way to do this in an optimized way at scale (without rewriting all rows manually)?
• Or is the best practice to simply re-write the data with a new TTL?
• The dataset size is about 500 GB, so I want to be careful about the approach.
What strategy would you recommend for updating/extending TTLs on existing data, and how should I proceed with this?
Thanks in advance for any pointer@Felipe_Cardeneti_Mendes! 
@Felipe_Cardeneti_Mendes**:** you need to rewrite the data, and add another 90d to their existing TTL.
@Saif_Ali**:** SSTable count: 2354
SSTables in each level: [6/4, 0, 195/100, 0, 2153]
Space used (live): 342.83 GiB
Space used (total): 342.83 GiB
Space used by snapshots (total): 0 bytes
Off heap memory used (total): 106.78 MiB
SSTable Compression Ratio: 0.558728
Number of partitions (estimate): 186070
Memtable cell count: 1149
Memtable data size: 68.54 MiB
Memtable off heap memory used: 91.88 MiB
Memtable switch count: 37983
Local read count: 18326724
Local read latency: 38.464 ms
Local write count: 9350587021
Local write latency: 0.010 ms
Pending flushes: 0
Percent repaired: 0.0
Bloom filter false positives: 1817
Bloom filter false ratio: 0.00571
Bloom filter space used: 434.8 KiB
Bloom filter off heap memory used: 425.6 KiB
Index summary off heap memory used: 14.49 MiB
Compression metadata off heap memory used: 0 bytes
Compacted partition minimum bytes: 51
Compacted partition maximum bytes: 268650950
Compacted partition mean bytes: 3917309
Average live cells per slice (last five minutes): 0.0
Maximum live cells per slice (last five minutes): 0
Average tombstones per slice (last five minutes): 0.0
Maximum tombstones per slice (last five minutes): 0
Dropped Mutations: 0 bytes
These are my tablestats, is there a way for me to get an estimate of how many rows are there? for me to analyse how much time will this process take?
@Guy: See here: https://forum.scylladb.com/t/get-the-approximate-number-of-rows-of-a-table/196
ScyllaDB Community NoSQL Forum: Get the approximate number of rows of a table?