Hi Bernhard,

I tried out several ways for connecting to a database from inside FreeSWITCH myself before writing the freeswitch.Dbh (which is rather simple actually - it only exposes already existing FreeSWITCH functionality in mod_lua).

My findings were that caching the connection as is provided by FreeSWITCH gives a huge speed increase compared to re-connecting all the time as must be done with LuaSQL. Perhaps there are ways to have a connection pool in ODBC but I didn't investigate that.


Here's a test with LuaSQL with ODBC driver:
require "luasql.odbc";
 
local env = assert(luasql.odbc())
local con = assert(env:connect("dsn","user","pass"))
local cur = assert(con:execute ("select 1 as foo, 2 as bar"))
 
local row = {}
while (cur:fetch(row, "a")) do
  for key, val in pairs(row) do
    stream:write(string.format("%25s : %s\n", key, val))
  end
  stream:write("\n")
end
 
cur:close()
con:close()
env:close()

freeswitch@fs-dev> hammer 1000 lua test_luasql_odbc.lua
+OK Finished in 38952 ms (min 29 ms, max 107 ms)


The same test with freeswitch.Dbh:

local dbh = assert(freeswitch.Dbh("dsn","user","pass"))
 
assert(dbh:query("select 1 as foo, 2 as bar", function(row) 
  for key, val in pairs(row) do
    stream:write(string.format("%25s : %s\n", key, val))
  end
  stream:write("\n")
end))
 
assert(dbh:release())

freeswitch@fs-dev> hammer 1000 lua test_lua_dbh.lua
+OK Finished in 2723 ms (min 1 ms, max 25 ms)

As you can see, with these tests the freeswitch.Dbh is about 14 times as fast as luasql.odbc. Of course this test is single threaded (the scripts are executed serially), so you'd get different results in real-world, and if you have 'long' running scripts with many queries on the same handle, the results would even out a bit.

(btw mod_hammer is a simple app in contrib/ledr/c that executes another app n times and shows how long it took)

I just tried compiling LuaSQL with Postgres driver to do the same tests, but that borked. Maybe you can give results of that ? I am curious how it behaves.

About having a native driver or odbc: odbc is just an abstraction layer which uses the native drivers itself, so I'd reckon it should be almost as fast - correct me if I'm wrong ?

I wrote some more about these tests on my blog at http://www.toyos.nl

Kind regards,

Leon


On Sep 16, 2010, at 8:52 PM, Bernhard Suttner wrote:

Hi,

from performance point of view, what should be used to connect to many different databases, luasql or freeswitch.dbh which does use ODBC?

The problem is, that is not only one database but 3-5 databases which are on 2-3 different hosts. Lua will be used to fetch the directory and dialplan directly from the db. Also live-data will be stored on the different databases. The advantage of freeswitch.dbh would be, that the db connections will be re-used. LUAsql would use the native e.g. postgres or mysql driver.

Thanks for any hint.

Best Regards,
Bernhard

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