1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
|
# frozen-string-literal: true
#
# The synchronize_sql extension checks out a connection from the pool while
# generating an SQL string. In cases where a connection is necessary
# in order to properly escape input, and multiple inputs in the query need
# escaping, this can result in fewer connection checkouts and better
# overall performance. In other cases this results in a performance decrease
# because a connection is checked out and either not used or kept checked out
# longer than necessary.
#
# The adapters where this extension may improve performance include amalgalite,
# mysql2, postgres, jdbc/postgresql, and tinytds. In these adapters, escaping
# strings requires a connection object for as proper escaping requires calling
# an escaping method on the connection object.
#
# This extension is most helpful when dealing with queries with lots of
# strings that need escaping (e.g. IN queries with long lists). By default,
# a connection will be checked out and back in for each string to be escaped,
# which under high contention can cause the query to spend longer generating
# the SQL string than the actual pool timeout (since every individual checkout
# will take less than the timeout, but the sum of all of them can be greater).
#
# This extension is unnecessary and will decrease performance if the single
# threaded connection pool is used.
#
module Sequel
class Dataset
module SynchronizeSQL
%w'insert select update delete'.each do |type|
define_method(:"#{type}_sql") do |*args|
if @opts[:sql].is_a?(String)
return super(*args)
end
db.synchronize(@opts[:server]) do
super(*args)
end
end
end
end
register_extension(:synchronize_sql, SynchronizeSQL)
end
end
|
