-
由 Ashwin Agrawal 提交于
This is partial cherry-pick from commit b3f300b9. In the QD, the distributed transactions become visible at the same time as the corresponding local ones, so we can rely on the local XIDs. This is true because the modification of local procarray and globalXactArray are protected by lock and hence a atomic operation during transaction commit. We have seen many situations where catalog queries run very slow on QD and potential reason is checking distributed logs. Process local distributed log cache fall short for this usecase as most of XIDs are unique and hence get frequent cache misses. Shared memory cache falls short as only caches 8 pages and many times need many more pages to be cached to be effective. Co-authored-by: NHubert Zhang <hzhang@pivotal.io> Co-authored-by: NGang Xiong <gangx@vmware.com>
48b13271