David Roussel wrote:
COPY invokes all the same logic as INSERT on the server side
(rowexclusive locking, transaction log, updating indexes, rules).
The difference is that all the rows are inserted as a single
transaction. This reduces the number of fsync's on the xlog,
which may be a limiting factor for you. You'll want to crank
WAL_BUFFERS and CHECKPOINT_SEGMENTS to match, though.
One of my streams has 6K records; I run with WB=1000, CS=128.


So what's the difference between a COPY and a batch of INSERT
statements.  Also, surely, fsyncs only occur at the end of a
transaction, no need to fsync before a commit has been issued, right?

I think COPY also has the advantage that for index updates it only grabs the lock once, rather than grabbing and releasing for each row. But I believe you are right that fsync only happens on COMMIT.


David

John =:->

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