diff options
Diffstat (limited to 'doc/src/sgml/html/logical-replication-restrictions.html')
| -rw-r--r-- | doc/src/sgml/html/logical-replication-restrictions.html | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/doc/src/sgml/html/logical-replication-restrictions.html b/doc/src/sgml/html/logical-replication-restrictions.html new file mode 100644 index 0000000..d922b80 --- /dev/null +++ b/doc/src/sgml/html/logical-replication-restrictions.html @@ -0,0 +1,57 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>31.6. Restrictions</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="logical-replication-conflicts.html" title="31.5. Conflicts" /><link rel="next" href="logical-replication-architecture.html" title="31.7. Architecture" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">31.6. Restrictions</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="logical-replication-conflicts.html" title="31.5. Conflicts">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="logical-replication.html" title="Chapter 31. Logical Replication">Up</a></td><th width="60%" align="center">Chapter 31. Logical Replication</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="logical-replication-architecture.html" title="31.7. Architecture">Next</a></td></tr></table><hr /></div><div class="sect1" id="LOGICAL-REPLICATION-RESTRICTIONS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">31.6. Restrictions</h2></div></div></div><p> + Logical replication currently has the following restrictions or missing + functionality. These might be addressed in future releases. + </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p> + The database schema and DDL commands are not replicated. The initial + schema can be copied by hand using <code class="literal">pg_dump + --schema-only</code>. Subsequent schema changes would need to be kept + in sync manually. (Note, however, that there is no need for the schemas + to be absolutely the same on both sides.) Logical replication is robust + when schema definitions change in a live database: When the schema is + changed on the publisher and replicated data starts arriving at the + subscriber but does not fit into the table schema, replication will error + until the schema is updated. In many cases, intermittent errors can be + avoided by applying additive schema changes to the subscriber first. + </p></li><li class="listitem"><p> + Sequence data is not replicated. The data in serial or identity columns + backed by sequences will of course be replicated as part of the table, + but the sequence itself would still show the start value on the + subscriber. If the subscriber is used as a read-only database, then this + should typically not be a problem. If, however, some kind of switchover + or failover to the subscriber database is intended, then the sequences + would need to be updated to the latest values, either by copying the + current data from the publisher (perhaps + using <code class="command">pg_dump</code>) or by determining a sufficiently high + value from the tables themselves. + </p></li><li class="listitem"><p> + Replication of <code class="command">TRUNCATE</code> commands is supported, but + some care must be taken when truncating groups of tables connected by + foreign keys. When replicating a truncate action, the subscriber will + truncate the same group of tables that was truncated on the publisher, + either explicitly specified or implicitly collected via + <code class="literal">CASCADE</code>, minus tables that are not part of the + subscription. This will work correctly if all affected tables are part + of the same subscription. But if some tables to be truncated on the + subscriber have foreign-key links to tables that are not part of the same + (or any) subscription, then the application of the truncate action on the + subscriber will fail. + </p></li><li class="listitem"><p> + Large objects (see <a class="xref" href="largeobjects.html" title="Chapter 35. Large Objects">Chapter 35</a>) are not replicated. + There is no workaround for that, other than storing data in normal + tables. + </p></li><li class="listitem"><p> + Replication is only supported by tables, including partitioned tables. + Attempts to replicate other types of relations, such as views, materialized + views, or foreign tables, will result in an error. + </p></li><li class="listitem"><p> + When replicating between partitioned tables, the actual replication + originates, by default, from the leaf partitions on the publisher, so + partitions on the publisher must also exist on the subscriber as valid + target tables. (They could either be leaf partitions themselves, or they + could be further subpartitioned, or they could even be independent + tables.) Publications can also specify that changes are to be replicated + using the identity and schema of the partitioned root table instead of + that of the individual leaf partitions in which the changes actually + originate (see <a class="link" href="sql-createpublication.html" title="CREATE PUBLICATION"><code class="command">CREATE PUBLICATION</code></a>). + </p></li></ul></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="logical-replication-conflicts.html" title="31.5. Conflicts">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="logical-replication.html" title="Chapter 31. Logical Replication">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="logical-replication-architecture.html" title="31.7. Architecture">Next</a></td></tr><tr><td width="40%" align="left" valign="top">31.5. Conflicts </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 31.7. Architecture</td></tr></table></div></body></html>
\ No newline at end of file |