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In PQnotifies discussion, reference PQsocket as function needed to get
file descriptor number for select(). (Suggestion from Ken Wright.)
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@ -1460,13 +1460,17 @@ deprecated as a waste of processing power.
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<para>
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A better way to check for NOTIFY
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messages when you have no useful queries to make is to call
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<function>PQconsumeInput()</function>, then check <function>PQnotifies()</function>.
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<function>PQconsumeInput()</function>, then check
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<function>PQnotifies()</function>.
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You can use <function>select</function>(2) to wait for backend data to
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arrive, thereby using no <acronym>CPU</acronym> power unless there is something
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to do. Note that this will work OK whether you use <function>PQsendQuery</function>/
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<function>PQgetResult</function> or simply <function>PQexec</function> for
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queries. You should, however, remember to check <function>PQnotifies()</function>
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after each <function>PQgetResult</function> or <function>PQexec</function> to see
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to do. (See <function>PQsocket()</function> to obtain the file descriptor
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number to use with <function>select</function>.)
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Note that this will work OK whether you submit queries with
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<function>PQsendQuery</function>/<function>PQgetResult</function> or simply
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use <function>PQexec</function>. You should, however, remember to
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check <function>PQnotifies()</function> after each
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<function>PQgetResult</function> or <function>PQexec</function>, to see
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if any notifications came in during the processing of the query.
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</para>
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