I vaguely recall that before he sat to meditate under the bodhi tree and was enlightened, he learned all the different techniques of meditation. Where does it say this?
In the Maha-Saccaka Sutta it describes his learning some meditation types/techniques, from teachers, before he sat and was enlightened:
Alara Kalama ... the dimension of nothingness.
Uddaka Ramaputta ... the dimension of neither perception nor non-perception.
Whatever brahmans or contemplatives in the past have felt painful, racking, piercing feelings due to their striving, this is the utmost. None have been greater than this. Whatever brahmans or contemplatives in the future will feel painful, racking, piercing feelings due to their striving, this is the utmost. None will be greater than this. Whatever brahmans or contemplatives in the present are feeling painful, racking, piercing feelings due to their striving, this is the utmost. None is greater than this. But with this racking practice of austerities I haven't attained any superior human state, any distinction in knowledge or vision worthy of the noble ones.
For sure what you have heard of is this incident. After the night of his Awakening, the Buddha spent 49 days experiencing the bliss of release. The knowledge of all that one will ever know in all of the three worlds was known to the Buddha within those 49 days. A mention of the vastness of this knowledge in him was mentioned when he was in the forest of simsapa trees. The Simsapa tree has very small leaves.
Taking a handful of the Simsapa leaves Buddha asked the monks, “Which is more, the leaves in my hand or the leaves in the forest?” The monks replied, “Of course, the leaves in the forest are many more than the leaves in your hand.”
Buddha said, “In the same way, what I learned in the course of my Awakening is like the leaves in the forest. What I have brought out to teach is like the leaves in my hand.”