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Added notes about using execute_batch with prepared statements

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Daniele Varrazzo 2017-02-02 02:40:03 +00:00
parent 9bac37baf7
commit 27652ed3b0
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doc/src/extras.rst
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@ -993,6 +993,38 @@ parameters. By reducing the number of server roundtrips the performance can be
.. versionadded:: 2.7
.. note::
`!execute_batch()` can be also used in conjunction with PostgreSQL
prepared statements using |PREPARE|_, |EXECUTE|_, |DEALLOCATE|_.
Instead of executing::
execute_batch(cur,
"big and complex SQL with %s %s params",
params_list)
it is possible to execute something like::
cur.execute("PREPARE stmt AS big and complex SQL with $1 $2 params")
execute_batch(cur, "EXECUTE stmt (%s, %s)", params_list)
cur.execute("DEALLOCATE stmt")
which may bring further performance benefits: if the operation to perform
is complex, every single execution will be faster as the query plan is
already cached; furthermore the amount of data to send on the server will
be lesser (one |EXECUTE| per param set instead of the whole, likely
longer, statement).
.. |PREPARE| replace:: :sql:`PREPARE`
.. _PREPARE: https://www.postgresql.org/docs/current/static/sql-prepare.html
.. |EXECUTE| replace:: :sql:`EXECUTE`
.. _EXECUTE: https://www.postgresql.org/docs/current/static/sql-execute.html
.. |DEALLOCATE| replace:: :sql:`DEALLOCATE`
.. _DEALLOCATE: https://www.postgresql.org/docs/current/static/sql-deallocate.html
.. autofunction:: execute_values
.. versionadded:: 2.7