[manigandham]

MySQL for years was far easier to install, configure and run than PostgreSQL, especially features like replication which was much better than other options. Big companies use these databases as more like simple key/value systems rather than complex relational schemas so strong replication and operational simplicity was favored over the rich featureset of Postgres.

Eventually Postgres caught up in most things, and the delay was in some part because of implementing those features "correctly" and with more thought, but it's still a delay that hurt the uptake in the early days.