@@ -7772,6 +7772,18 @@ psql "dbname=postgres replication=database" -c "IDENTIFY_SYSTEM;"
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<sect1 id="protocol-changes">
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<title>Summary of Changes since Protocol 2.0</title>
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+ <para>
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+ This section provides a quick checklist of changes, for the benefit of
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+ developers trying to update existing client libraries to protocol 3.2.
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+ </para>
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+
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+ <para>
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+ The secret key used in query cancellation was enlarged from 4 bytes to a
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+ variable length field. The BackendKeyData message was changed to accommodate
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+ that, and the CancelRequest message was redefined to have a variable length
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+ payload.
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+ </para>
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+
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<para>
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This section provides a quick checklist of changes, for the benefit of
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developers trying to update existing client libraries to protocol 3.0.
@@ -7871,5 +7883,15 @@ psql "dbname=postgres replication=database" -c "IDENTIFY_SYSTEM;"
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The EmptyQueryResponse ('<literal>I</literal>') message used to include an empty
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string parameter; this has been removed.
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</para>
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+
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+ <para>
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+ In version 17 SSL negotiation was modified.
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+ Before version 17 To initiate an SSL-encrypted connection, the frontend initially
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+ sends an SSLRequest message rather than a StartupMessage. The server then responds
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+ with a single byte containing S or N, indicating that it is willing or unwilling
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+ to perform SSL, respectively. After which the frontend begins SSL negotiation
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+ Starting in version 17 the server will recognize connections which immediately
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+ begin SSL negotiation without any previous SSLRequest packets
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+ </para>
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</sect1>
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</chapter>
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