Log every SQL query to database in Rails - sql

Question

I want to save to a log file some SQL query rails performs, (namely the CREATE, UPDATE and DELETE ones)
therefore I need to intercept all queries and then filter them maybe with some regexp and log them as needed.
Where would I put such a thing in the rails code?

Answer 1

Here a simplified version of what c0r0ner linked to, to better show it:
connection = ActiveRecord::Base.connection
class << connection
alias :original_exec :execute
def execute(sql, *name)
# try to log sql command but ignore any errors that occur in this block
# we log before executing, in case the execution raises an error
begin
File.open(Rails.root.join("/log/sql.txt"),'a'){|f| f.puts Time.now.to_s+": "+sql}
rescue Exception => e
;
end
# execute original statement
original_exec(sql, *name)
end
end

Answer 2

SQL logging in rails -
In brief - you need to override ActiveRecord execute method. There you can add any logic for logging.

Answer 3

As a note for followers, you can "log all queries" like Rails - See generated SQL queries in Log files and then grep the files for the ones you want, if desired.

Answer 4

If you are using mysql I would look into mysqlbinlog . It is going to track everything that potentially updates data. you can grep out whatever you need from that log easily.
http://dev.mysql.com/doc/refman/5.0/en/mysqlbinlog.html
http://dev.mysql.com/doc/refman/5.0/en/binary-log.html

Answer 5

SQL Server? If so...
Actually, I'd do this at the SQL end. You could set up a trace, and collect every query that comes through a connection with a particular Application Name. If you save it to a table, you can easily query that table later.

Answer 6

Slightly updated version of #luca's answer for at least Rails 4 (and probably Rails 5)
Place this in config/initializers/sql_logger.rb:
connection = ActiveRecord::Base.connection
class << connection
alias :original_exec :execute
def execute(sql, *name)
# try to log sql command but ignore any errors that occur in this block
# we log before executing, in case the execution raises an error
begin
File.open(Rails.root.join("log/sql.log"), 'a') do |file|
file.puts Time.now.to_s + ": " + sql
end
rescue Exception => e
"Error logging SQL: #{e}"
end
# execute original statement
original_exec(sql, *name)
end
end