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add note about LOB & LONG cols

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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@290726 c90b9560-bf6c-de11-be94-00142212c4b1
This commit is contained in:
Christopher Jones 2009-11-13 23:57:53 +00:00
parent 4781f3425d
commit e7a86f9adf
1 changed files with 15 additions and 12 deletions
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27
reference/oci8/functions/oci-set-prefetch.xml
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@ -34,17 +34,17 @@
re-executed statements or by other connections.
</para>
<para>
Call <function>oci_set_prefetch</function> before
calling <function>oci_execute</function>.
Call <function>oci_set_prefetch</function> before
calling <function>oci_execute</function>.
</para>
<para>
A tuning goal is to set the prefetch value to a reasonable size
for the network and database to handle. For queries returning a
very large number of rows, overall system efficiency might be
better if rows are retrieved from the database in several chunks
(i.e set the prefetch value smaller than the number of rows).
This allows the database to handle other users' statements while
your script is processing the current set of rows.
A tuning goal is to set the prefetch value to a reasonable size for
the network and database to handle. For queries returning a very
large number of rows, overall system efficiency might be better if
rows are retrieved from the database in several chunks (i.e set the
prefetch value smaller than the number of rows). This allows the
database to handle other users' statements while your script is
processing the current set of rows.
</para>
<para>
Query prefetching was introduced in Oracle 8i. REF CURSOR
@ -52,9 +52,12 @@
linked with Oracle 11gR2 Client libraries and connected to 11gR2 or
previous versions of the database. Nested cursor prefetching was
introduced in Oracle 11gR2 and requires both the Oracle Client
libraries and the database to be version 11gR2. The prefetch value
is ignored and single-row fetches will be used when prefetching is
not supported.
libraries and the database to be version 11gR2.
</para>
<para>
Prefetching is not supported when queries contain LONG or LOB
columns. The prefetch value is ignored and single-row fetches will
be used in all the situations when prefetching is not supported.
</para>
</refsect1>