# Verifying Backend Data

**URL:** https://forum.duplicati.com/t/verifying-backend-data/348
**Category:** Support
**Created:** [August 31, 2017, 1:32am UTC](https://forum.duplicati.com/t/verifying-backend-data/348 "2017-08-31T01:32:23Z")
**Posts on this page:** 1
**Showing post:** 65

<div class="post-metadata">

### Author: ![natocccp](https://forum.duplicati.com/letter_avatar_proxy/v4/letter/n/a87d85/32.png) [@natocccp](https://forum.duplicati.com/u/natocccp)
#### Post date: [April 18, 2019, 8:17pm UTC](https://forum.duplicati.com/t/verifying-backend-data/348/65 "2019-04-18T20:17:41Z")

</div>

Dear Duplicati authors,

analysis of user RGupta is correct and issue of “Verifying Backend Data” is not resolved in 2.0.4.17 build.

What is recommended to be changed is:  
a)  
create index i1 on BlocklistHash(Hash);

b) LocalDatabase(1301) issue commands:  
PRAGMA optimize;  
ANALYZE sqlite\_master;  
ANALYZE Block;  
ANALYZE BlocklistHash;  
ANALYZE BlocksetEntry;

c) in LocalDatabase.cs(1304):  
var sql = string.Format(@“SELECT ““A””.”“Hash”", ““C””."“Hash”" FROM " +  
@"(SELECT bb1."“BlocksetID”", bb2."“Hash”", \* FROM ““BlocklistHash”” bb1,"“Block”" bb2 WHERE bb1."“Hash”" = bb2."“Hash”" AND bb2."“VolumeID”" = ?) A, " +  
@" ““BlocksetEntry”” B, ““Block”” C WHERE ““B””."“BlocksetID”" = ““A””."“BlocksetID”" AND " +  
@" ““B””."“Index”" \>= ("“A”"."“Index”" \* {0}) AND ““B””."“Index”" \< (("“A”"."“Index”" + 1) \* {0}) AND ““C””."“ID”" = ““B””."“BlockID”" " +  
@" ORDER BY ““A””."“BlocksetID”", ““B””."“Index”"",  
blocksize / hashsize

My development laptop has over 10 million local files.  
Even in 2.0.4.17 “Verifying Backend Data” takes over 24 hours before I kill service.  
With changes it takes fraction of a second.

Thanks

---

_[View the full topic](https://forum.duplicati.com/t/verifying-backend-data/348)._