On Tue, Mar 16, 2021 at 4:07 PM Dilip Kumar <dilipbal...@gmail.com> wrote: > > INSERT TIME > Head: 17418.299 ms Patch: 20956.231 ms > > CTAS TIME: > Head: 12837.872 ms Patch: 16775.739 ms
On quick analysis with perf it appeared that the performance is degrading because of deforming - 16.19% 3.54% postgres postgres [.] CompareCompressionMethodAndDecompress - 12.65% CompareCompressionMethodAndDecompress - 12.57% slot_getallattrs - 12.56% slot_getsomeattrs - 12.53% slot_getsomeattrs_int - 12.50% tts_buffer_heap_getsomeattrs slot_deform_heap_tuple So I think in the case of direct insert it needs to deform because I am calling CompareCompressionMethodAndDecompress after ExecCopySlot and that is why we have to deform every time so maybe that can be avoided by calling CompareCompressionMethodAndDecompress before ExecCopySlot. But in the case of CTAS or INSERT INTO SELECT we can not avoid deforming because we might get the formed tuple from the source table. I put a temporary hack to keep the map of the varlena attribute and use it across the tuple but it did not improve the performance in this case because the main bottleneck is slot_getallattrs. I think this should help where we don't have any varlena, but first I need to test whether we can any performance regression in those cases at all. -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com