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 the surname Rooney, there are 12,112 B rcds dating from abt 1742, and 6,332 M rcds dating from 1734. For the B rcds, the frequency distribution is as follows: Antrim647 Armagh552 Cavan_192 Cork__67 Down__ 1,989 Fermanagh465 Galway___669 Kildare__844 Kilkenny__74 Leitrim2,827 Limerick__49 Longford_155 Louth____790 Mayo_____396 Meath____569 Roscommon163 Sligo____461 Tipperary_62 Tyrone___276 Westmeath458 Wicklow__253
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.