On Tue, Nov 19, 2019 at 11:55:44PM +0100, Laurenz Albe wrote: > On Tue, 2019-11-19 at 18:55 +0000, PG Doc comments form wrote: > > I experimented with Bulk load and COPY. > > Loading in COPY was very fast. > > However, after COPYing data from a CSV file to PostgreSQL Table. The query > > execution took lot of time for 1 of the first 4 queries. > > Only this slow query was taking so much time, that even if I had used normal > > bulk load, it would have been faster in total. > > Then all other Query executions took equal time as it took while querying a > > table after the Bulk data load method. > > > > So, I want to know the exact reason what's the issue with COPY. > > How exactly they differ? The only thing from the document I could identify > > was row security. > > But it did not mention anything about indexing. Like, in Bulk load, do > > indices(or constraint checks) are created with data loading? > > & in COPY it's done after? so when indices are being created that query > > slows down?? > > > > Please reply soon with more details or send a link where I can read it in > > depth. > > That cannot be answered without knowing the exact statements and the > table definitions.
I wonder if it is the overhead of rewriting all the rows to set the per-row HEAP_XMIN_COMMITTED bit. Unfortunately, I don't know a way to test this hypothesis. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
