Resources Exceeded During Query Execution: Custom Dimensions & MAX(IF(...)) - python-2.7

Question

I'm performing what I thought was a simple events query in BigQuery with two custom dimensions. When trying to execute this query for year-to-date, I get the following error:
query: Resources exceeded during query execution. (error code:
resourcesExceeded)
Research of this error and investigation of the 'resourcesExceeded' error code indicates that this happens most frequently when using windowed functions, joins, count(distinct()) or group by each, none of which I am using here. The only thing I am doing is order by Date asc, which doesn't appear to eliminate the error when that line is removed. Since this is a shard resources issue, I think this has to be related to the two custom dimensions I'm trying to pull, since the MAX/IF function seem to be the most resource intensive portions of this query. Here's a snippet of the query I'm running:
SELECT
DATE,
userId,
fullVisitorId,
visitId,
trafficSource.source,
trafficSource.medium,
trafficSource.campaign,
trafficSource.adContent,
MAX(IF (hits.customDimensions.INDEX = 1,hits.customDimensions.value,NULL)) WITHIN RECORD AS XXXXXX,
MAX(IF (hits.customDimensions.INDEX = 2,hits.customDimensions.value,NULL)) WITHIN RECORD AS YYYYYY,
totals.visits,
totals.bounces,
totals.pageviews
FROM (
TABLE_DATE_RANGE([########.ga_sessions_],
TIMESTAMP('2016-01-01'), # start date
TIMESTAMP('2016-07-31')) # end date
)
ORDER BY DATE ASC;
I've tried this query both through the BigQuery console UI as well as from the command line. I've also set the option, 'allowLargeResults' to True.