Patent ID: 9679012
Date: 2017-06-13
CPC Classifications: G06F

Claim:
1. A computer-implemented method comprising: representing, by a first distributed system, as an external table, data stored in a second distributed system; receiving, by a first master node of a first distributed system, a query that requests rows of data of the external table representing data stored in the second distributed system, obtaining, by the first master node, statistics of the data stored in the second distributed system represented by the external table; evaluating, by the first master node, a plurality of query plans using one or more cost criteria, including computing a cost associated with each of the query plans, wherein the cost criteria includes (i) a scanning cost of reading all the data stored in the second distributed system based on the statistics for broadcast to the segment nodes of the first distributed system, and (ii) a scanning cost of reading, from data nodes of the second distributed system in parallel, portions of the external table requested by segment nodes of the first distributed system; selecting, by the first master node, a query plan from the plurality of query plans based at least in part on the cost associated with each of the query plans; and computing, by the first master node, a result for the received query according to the selected query plan.