Bug #93942 Massive deletion of records that were inserted several during the same day
Submitted: 15 Jan 19:25 Modified: 16 Jan 10:34
Reporter: Amador Rodriguez Email Updates:
Status: Can't repeat Impact on me:
None 
Category:MySQL Server: DML Severity:S2 (Serious)
Version:5.7.17 OS:Microsoft Windows (Dedicated server)
Assigned to: CPU Architecture:x86 (Win 64)

[15 Jan 19:25] Amador Rodriguez
Description:
As we got into our office at 8am, many records were inserted at different tables of our databases. From that time onwards, until about 1pm, those records were read successfully several times, hundreds of times without any problem.

At one point between 1pm and 2pm all those records disappeared, like they had never existed before. Even the auto increment values for those tables returned to the values they had yesterday.

The database returned to a state similar to that of last night at 12am. I cannot guarantee that, because some other records, like user's profiles could have been updated, but for 100% I can tell that all records inserted today were deleted from all tables.

How to repeat:
I hope it will never repeat but there must be a cause to this problem. It's very important to know what happened.
[15 Jan 23:10] Miguel Solorzano
Thank you for the bug report. We need repeatable test case to process this bug report. Thanks.
[16 Jan 10:34] Amador Rodriguez
Hi, as I have been able to access the server logs, I have found reports like InnoDB: Database was not shutdown normally!, InnoDB: Starting crash recovery, InnoDB: Doing recovery: scanned up to log sequence number 101077153 and so on

I have found out that apparently this was not a problem related to MySQL but the the whole Windows Server. Something happened that caused the server to restart unexpectedly and it seems as they applied a full backup, so MySql took the data from the previous day.

Our hosting provider for the dedicated server are looking into the issue right now.