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Handle heap rewrites even better in logical decoding

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Logical decoding should not publish anything about tables created as
part of a heap rewrite during DDL.  Those tables don't exist externally,
so consumers of logical decoding cannot do anything sensible with that
information.  In ab28feae2b, we worked
around this for built-in logical replication, but that was hack.

This is a more proper fix: We mark such transient heaps using the new
field pg_class.relwrite, linking to the original relation OID.  By
default, we ignore them in logical decoding before they get to the
output plugin.  Optionally, a plugin can register their interest in
getting such changes, if they handle DDL specially, in which case the
new field will help them get information about the actual table.

Reviewed-by: Craig Ringer <craig@2ndquadrant.com>
This commit is contained in:
Peter Eisentraut
2018-03-21 09:13:24 -04:00
parent be8a7a6866
commit 325f2ec555
20 changed files with 113 additions and 103 deletions
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12
doc/src/sgml/catalogs.sgml
View File

@ -1923,6 +1923,18 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
<entry>True if table is a partition</entry>
</row>
<row>
<entry><structfield>relrewrite</structfield></entry>
<entry><type>oid</type></entry>
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
<entry>
For new relations being written during a DDL operation that requires a
table rewrite, this contains the OID of the original relation;
otherwise 0. That state is only visible internally; this field should
never contain anything other than 0 for a user-visible relation.
</entry>
</row>
<row>
<entry><structfield>relfrozenxid</structfield></entry>
<entry><type>xid</type></entry>

5
doc/src/sgml/logicaldecoding.sgml
View File

@ -486,12 +486,17 @@ typedef void (*LogicalDecodeStartupCB) (struct LogicalDecodingContext *ctx,
typedef struct OutputPluginOptions
{
OutputPluginOutputType output_type;
bool receive_rewrites;
} OutputPluginOptions;
</programlisting>
<literal>output_type</literal> has to either be set to
<literal>OUTPUT_PLUGIN_TEXTUAL_OUTPUT</literal>
or <literal>OUTPUT_PLUGIN_BINARY_OUTPUT</literal>. See also
<xref linkend="logicaldecoding-output-mode"/>.
If <literal>receive_rewrites</literal> is true, the output plugin will
also be called for changes made by heap rewrites during certain DDL
operations. These are of interest to plugins that handle DDL
replication, but they require special handling.
</para>
<para>