Gartner said RDBMS software revenue totaled $13.8 billion in 2005, an 8.3 percent spike from 2004 revenue.
IDC, which uses different metrics to arrive at its sales totals, said RDBMS sales grew 9.4 percent to $14.6 billion last year from 2004.
Relational databases (define) are organized in tables and accessed based on the relationships between different data objects. Such databases often include a Structured Query Language (SQL) (define) application programming interface.
For example, IDC analyst Carl Olofson said in his report that businesses have been upgrading their database systems to include master data management software to better meet compliance rules for information governance and record retention.
Buying new or upgrading old database systems has driven spending in the sector and padded the pockets of market leaders Oracle, IBM and Microsoft.
Gartner said Oracle's database share grew 7.8 percent to 48.6 percent from 2004 to 2005, with IBM coming in at a distant second at 22 percent on 6.3 percent year-over-year growth.
Microsoft tallied 15 percent of the market in 2005, but boasted a 16.6 growth rate thanks to pent-up demand for SQL Server 2005.
Gartner said Teradata and Sybase took 3.2 percent and 2.9 percent, respectively. The remaining 8.2 percent went to smaller vendors and open source database providers.
While MySQL, Ingres and Berkeley DB may have only small percentages of the total RDBMS market, open source database vendors showed the strongest growth, according to Gartner analyst Colleen Graham.