On 30-12-2017 12:41, eliflavio@... [firebird-support] wrote:

> My software is running on a client and sometimes something happens and a
> SELECT command in a table (only in this table) freezes. Then I just do a
> backup (only a backup, without restore) and the command runs correct again.
>
> What could it be?

As a starting point, answer the following questions

What is the output of gstat -h on the database after (or during) the freeze?
What is the output of gfix -l on the database during the freeze?
What is the output of fb_lock_print -d <path-to-your-database> during
the freeze?
What is the transaction configuration of the transaction doing the select?
Do you have concurrent transactions modifying the table, if so, what is
their transaction configuration
What is in firebird.log of the server around the time of the freeze?
What is your Firebird version (full version please)?
Classic, SuperServer, or SuperClassic?
What client do you use (name + full version)?

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Mark Rotteveel