I research the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For Marg(aret) McCloskey B 1831 +/- 4 yrs somewhere in Ireland with the father's forename unknown, I found 10 rcds: 1827 Antrim, 1828 Limerick, 1829 Meath, 1832 Antrim, 1833 Tyrone, 1834 Tyrone, 1834 Louth, 2-1835 Meath, and 1835 Tyrone.
Best bet is to contact the diocese of San Francisco for its early marriage rcds. These usually listed the parents' names for the bride and groom and sometimes placenames. You need some of this info to really search Irish records.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.