Data sharing within the AI ecosystem brings both social benefits and social costs. To understand the trade-off and study efficiency of the data market, I specify the economic mechanism of data sharing and explore factors that should be considered when promoting data sharing: economic characteristics of shared data, competition among firms in the AI ecosystem, and the transaction mechanism. If these conditions are met, data sharing can increase the number of innovations and productivity of the firms in the AI ecosystem, leading to economic growth. If data sharing policies are implemented without reflecting these factors, the production of data would decrease and negative externalities can occur in the AI ecosystem.