TAJO-2036: Prevent out of memory in the master server, if the query result is large

[combineads]

This problem will occur frequently in our production server.
Please confirm.

[jihoonson]

numOfRows = (long)((float)(resultRows) * ((float)sizeLimit / (float) resultRows)); on the 506 line looks not necessary. Would you remove it, too?

[combineads]

@jihoonson Anything else to commit this PR?

[jihoonson]

@combineads, sorry for late response.
Actually, my intention was to keep both factors, but clean some unnecessary codes.
I think we need to keep only the max number of rows rather than max byte size in the future. However, for now, it would be ok if we support both factors. How about adding the max number of rows again?

[combineads]

Hi @jihoonson .
I did to add the row limit field.
Thank you for review.

[jihoonson]

limitRow also needs to be added to returnValue.

[jihoonson]

Oh, my mistake. Never mind.

[combineads]

Hi @jihoonson .
I did to remove the max row limit.
Thank you for review.

[jihoonson]

+1 LGTM. This patch does not relate to unit tests.
I'll commit shortly.