[Devel] Postgres reconnect patch

Klaus Darilion klaus.mailinglists at pernau.at
Fri Aug 5 16:04:08 CEST 2005

Michael Ulitskiy wrote:
> Hi Klaus,
> I've seen the problem described by Klaus too, but first of all I was 
> concerned that postgres module cannot reconnect to db after connection 
> failure. It crashed openser.

I tried CVS version and stoped postgres during operation. Then, openser 
failed to update the location table (of course) but did not crashed. 
Maybe it depends on the module which tries to access the database. 
Nevertheless, reconnect failed after postgres returned.

Then I applied your patch. Now, reconnect works.
Although, the debug message looks a little bit strange when the postgres 
module tries to reconnect when the db ist still down:

   7(32748) PG[142] connect_db could not connect to server: ÿÿÿÿ



> I've done some research on the module source code and I  believe
> I've found a logical mistake in it.
> The issue is that parse_sql_url() function is supplied with the only copy
> of sql url and it corrupts it. So if the connection fails and module
> tries to reparse url it fails as CON_SQLURL(_h) is corrupted by first
> parsing. 
> I've created a simple patch that corrects the problem. What it does it
> it introduce a temporary buffer with sql url string for parse_sql_url to work
> on. Also it makes so that original sql url is not deleted from connection structure
> until db_close() is called.
> Patch is attached.
> Also if in dbase.c in db_init() function you comment out the following:
> /*
>         if (connect_db(res) < 0)
>         {
>                 PLOG("db_init", "Error while trying to open database, FATAL\n")
>                 aug_free(res);
>                 return((db_con_t *) 0);
>         }
> */
> you'll get a "delay connect until used" feature that can be usefull due to lack
> of connection pool for postgres.
> Could please some of developers review this patch?
> Michael
> On Thursday 04 August 2005 11:39 am, Klaus Darilion wrote:
>>I had several situations in which openser crashed if the DB lookup 
>>fails, e.g:
>>table does not exist (acc module)
>>wrong SQL query (lcr module)
>>Whereas is some cases (wrong table permissions, avpops module) openser 
>>keeps running.
>>I do not know if these problems also occurs with mysql. If not, the 
>>postgresql module would really need some review.

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