In agreeing this week to pay US$1 billion for MySQL, Sun Microsystems said it hopes to make MySQL's open-source database more attractive to enterprise users. But Sun has a lot of work to do, according to some MySQL users.

And it isn't just technical fixes that are needed, they said. Although Sun described MySQL as "an open-source icon," it also will have to mend fences with users who are unhappy about the database vendor's sales tactics and complain that it has ignored their development suggestions.

For instance, within hours of the proposed acquisition's announcement on Wednesday, Don MacAskill, CEO and "chief geek" at SmugMug, said in a blog posting that he is "seriously considering" not renewing the online photo-sharing service's platinum-level MySQL Enterprise support contract. "I probably wouldn't pay for MySQL as it stands today," he wrote.

In an interview, MacAskill said MySQL has performance and concurrency issues when it's paired with InnoDB, the most widely used storage engine for the database. In particular, the problems affect systems with multicore processors. "That's turning out to be a pretty major scalability roadblock for a lot of us," he said.

Google Inc. and other MySQL users have created patches designed to fix the performance problems. But MacAskill said that the open-source vendor has yet to add the patches to the database, despite requests that it do so from him and other users.

"I often wonder why they haven't been accepted and just pushed into the MySQL release," he said, adding that it will be "in [Sun's] best interest to see MySQL get really good at concurrency really fast."

MySQL officials said the patch question is now Sun's to answer - even though the acquisition isn't expected to be completed until late this quarter or early in the second quarter. Sun couldn't immediately be reached for comment on the issue.

There are plenty of other things that also need fixing in MySQL, according to a blog posting by Jeremy Cole, a former user of the database at Yahoo Inc. who now is a MySQL consultant at Proven Scaling.

"There are a lot of areas where MySQL has been lacking for a long time, and the power users have been either crying in their beer or doing the work themselves," Cole wrote. For instance, he cited problems with the database's replication, logging and internal memory allocation features.

In addition, Cole criticized MySQL's sales and marketing team and said that the company's development model for MySQL Enterprise is "broken."

Jonathan Schwartz, Sun's CEO and president, said during a teleconference Wednesday that the biggest impediment to MySQL's growth has been its inability "to give peace of mind to a global company that wants to put MySQL into mission-critical deployments." Schwartz added that the open-source database will benefit from Sun's broader enterprise reach.

Sun already distributes the PostgreSQL open-source database on its Solaris-based servers; on the company's Web site, it touts PostgreSQL for Solaris 10 as "the open-source enterprise database platform of choice." But Schwartz described the purchase of MySQL as "the most important acquisition" ever made by Sun -- indicating that MySQL's software likely will eclipse PostgreSQL on Sun's priority list.

In addition to the internal issues that Sun faces at MySQL, the deal could complicate its relationship with Oracle Corp., which is Sun's largest database partner. MySQL competes directly with Oracle and other database vendors. Also, Oracle owns InnoDB after buying the storage engine's developer, Innobase Oy, in late 2005.

"Now that [MySQL] is going to be supported by a major vendor, there's lots of companies that are going to give it a serious look," said Robert Lepanto, Oracle applications manager at AppCentric Solutions LLC in Stamford, Conn. "I would think that's a serious long-term threat to Oracle."

Lepanto, who also is president of the New York City Metro Oracle Applications Users Group, added that he's surprised that Oracle "didn't buy [MySQL] first to squash the competition."

Daniel Grim, executive director of networks and systems at the University of Delaware in Newark, has an enterprisewide license for Oracle databases but also sees value in the open-source alternatives.

"We've often found Oracle is more complex and more cumbersome than things like PostgreSQL and MySQL are," Grim said. "So we use those for small applications, although some of [the] applications are quite large, such as monitoring networking traffic."

In addition to Google, Yahoo and SmugMug, MySQL's wide-ranging customer list includes some of the darlings of the Web 2.0 era, such as Facebook Inc. and YouTube Inc., as well as more traditional businesses like Toyota Motor and Southwest Airlines.

The buyout deal ends widespread speculation about the future of MySQL. Before agreeing to sell to Sun, the company had been on track for an initial public offering, said Kevin Harvey, a partner at venture firm Benchmark Capital and chairman of MySQL's board of directors. Benchmark has a 26% stake in MySQL, and it uses the open-source database to help power its Web site.

One of the questions that Sun continually faces is how it can improve its bottom line while offering key technologies such as Solaris and Java on an open-source basis. But Harvey said that from his perspective, open source "very clearly" can be "turned into a fantastic business model."

Brian Fonseca and Eric Lai contributed to this story.