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+<!-- doc/src/sgml/test-decoding.sgml -->
+
+<sect1 id="test-decoding" xreflabel="test_decoding">
+ <title>test_decoding</title>
+
+ <indexterm zone="test-decoding">
+  <primary>test_decoding</primary>
+ </indexterm>
+
+ <para>
+  <filename>test_decoding</filename> is an example of a logical decoding
+  output plugin. It doesn't do anything especially useful, but can serve as
+  a starting point for developing your own output plugin.
+ </para>
+
+ <para>
+  <filename>test_decoding</filename> receives WAL through the logical decoding
+  mechanism and decodes it into text representations of the operations
+  performed.
+ </para>
+
+ <para>
+  Typical output from this plugin, used over the SQL logical decoding
+  interface, might be:
+
+<programlisting>
+postgres=# SELECT * FROM pg_logical_slot_get_changes('test_slot', NULL, NULL, 'include-xids', '0');
+   lsn     | xid |                       data
+-----------+-----+--------------------------------------------------
+ 0/16D30F8 | 691 | BEGIN
+ 0/16D32A0 | 691 | table public.data: INSERT: id[int4]:2 data[text]:'arg'
+ 0/16D32A0 | 691 | table public.data: INSERT: id[int4]:3 data[text]:'demo'
+ 0/16D32A0 | 691 | COMMIT
+ 0/16D32D8 | 692 | BEGIN
+ 0/16D3398 | 692 | table public.data: DELETE: id[int4]:2
+ 0/16D3398 | 692 | table public.data: DELETE: id[int4]:3
+ 0/16D3398 | 692 | COMMIT
+(8 rows)
+</programlisting>
+ </para>
+
+<para>
+  We can also get the changes of the in-progress transaction, and the typical
+  output might be:
+
+<programlisting>
+postgres[33712]=#* SELECT * FROM pg_logical_slot_get_changes('test_slot', NULL, NULL, 'stream-changes', '1');
+    lsn    | xid |                       data
+-----------+-----+--------------------------------------------------
+ 0/16B21F8 | 503 | opening a streamed block for transaction TXN 503
+ 0/16B21F8 | 503 | streaming change for TXN 503
+ 0/16B2300 | 503 | streaming change for TXN 503
+ 0/16B2408 | 503 | streaming change for TXN 503
+ 0/16BEBA0 | 503 | closing a streamed block for transaction TXN 503
+ 0/16B21F8 | 503 | opening a streamed block for transaction TXN 503
+ 0/16BECA8 | 503 | streaming change for TXN 503
+ 0/16BEDB0 | 503 | streaming change for TXN 503
+ 0/16BEEB8 | 503 | streaming change for TXN 503
+ 0/16BEBA0 | 503 | closing a streamed block for transaction TXN 503
+(10 rows)
+</programlisting>
+ </para>
+
+</sect1>