1. A method for a database system comprising a first instantiation of a columnar table in a volatile memory and a second instantiation of the columnar table in a persisted memory, the method comprising: receiving a transaction to change the columnar table; recording the transaction within a delta structure in the volatile memory; recording the transaction within a log of the persisted memory; receiving an instruction to merge the delta structure in the volatile memory with the first instantiation of the columnar table in the volatile memory; and in response to the instruction, merging the delta structure in the volatile memory with the first instantiation of the columnar table in the volatile memory to create a merged columnar table in the volatile memory, and not storing the merged columnar table in the persisted memory.