Re: Autovacuum launcher

I've fixed all other problems according to suggestions, including adding
a SignalSomeChildren(int signal, bool only_autovac) function to
postmaster so that it can shut autovac workers down in case of smart
shutdown.

Tom Lane wrote:

> Making InitPostgres's call API vary depending on
> IsAutoVacuumWorkerProcess seems really ugly, and unnecessary.
> Why not just test for dbname == NULL or some other convention
> expressed by the arguments themselves?

Hmm, yeah. Modified version below. In BootstrapMain, it surprises me
that the dbname is getting computed, and seems to be a required
parameter, when it doesn't seem to be used at all. That code needs a
serious refactoring ...

/* --------------------------------
* InitPostgres
* Initialize POSTGRES.
*
* The database can be specified by name, using the in_dbname parameter, or by
* OID, using the dboid parameter. In the latter case, the computed database
* name is passed out to the caller as a palloc'ed string in out_dbname.
*
* In bootstrap mode no parameters are used.
*
* The return value indicates whether the userID is a superuser. (That
* can only be tested inside a transaction, so we want to do it during
* the startup transaction rather than doing a separate one in postgres.c.)
*
* As of PostgreSQL 8.2, we expect InitProcess() was already called, so we
* already have a PGPROC struct ... but it's not filled in yet.
*
* Note:
* Be very careful with the order of calls in the InitPostgres function.
* --------------------------------
*/
bool
InitPostgres(const char *in_dbname, Oid dboid, const char *username,
char **out_dbname)
{
bool bootstrap = IsBootstrapProcessingMode();
bool autovacuum = IsAutoVacuumWorkerProcess();
bool am_superuser;
char *fullpath;
char dbname[NAMEDATALEN];

/*
* Set up the global variables holding database id and path. But note we
* won't actually try to touch the database just yet.
*
* We take a shortcut in the bootstrap case, otherwise we have to look up
* the db name in pg_database.
*/
if (bootstrap)
{
MyDatabaseId = TemplateDbOid;
MyDatabaseTableSpace = DEFAULTTABLESPACE_OID;
}
else
{
/*
* Find tablespace of the database we're about to open. Since we're not
* yet up and running we have to use one of the hackish FindMyDatabase
* variants, which look in the flat-file copy of pg_database.
*
* If the in_dbname param is NULL, lookup database by OID.
*/
if (in_dbname == NULL)
{
if (!FindMyDatabaseByOid(dboid, dbname, &MyDatabaseTableSpace))
ereport(FATAL,
(errcode(ERRCODE_UNDEFINED_DATABASE),
errmsg("database %u does not exist", dboid)));
MyDatabaseId = dboid;
/* pass the database name to the caller */
*out_dbname = pstrdup(dbname);
}
else
{
if (!FindMyDatabase(in_dbname, &MyDatabaseId, &MyDatabaseTableSpace))
ereport(FATAL,
(errcode(ERRCODE_UNDEFINED_DATABASE),
errmsg("database \"%s\" does not exist",
in_dbname)));
/* our database name is gotten from the caller */
strlcpy(dbname, in_dbname, NAMEDATALEN);
}
}

--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support