14.4.2. Use COPY

Use COPY to load all

the rows in one command, instead of using a series of

INSERT commands. The COPY command is optimized for loading large

numbers of rows; it is less flexible than INSERT, but incurs significantly less overhead

for large data loads. Since COPY is a

single command, there is no need to disable autocommit if you

use this method to populate a table.

If you cannot use COPY, it might

help to use PREPARE

to create a prepared INSERT statement,

and then use EXECUTE as many times as

required. This avoids some of the overhead of repeatedly

parsing and planning INSERT. Different

interfaces provide this facility in different ways; look for

"prepared statements"

in the

interface documentation.

Note that loading a large number of rows using COPY is almost always faster than using

INSERT, even if PREPARE is used and multiple insertions are

batched into a single transaction.

COPY is fastest when used within

the same transaction as an earlier CREATE

TABLE or TRUNCATE command. In

such cases no WAL needs to be written, because in case of an

error, the files containing the newly loaded data will be

removed anyway. However, this consideration does not apply when

archive_mode is

set, as all commands must write WAL in that case.

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