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In v10 release notes, call out sequence changes as a compatibility item.

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The previous description didn't make it clear that this change
potentially breaks applications, partly because the entry wasn't even
in the compatibility-hazard section.  Move and clarify.

Discussion: https://postgr.es/m/603f3f0a-f89d-ae8b-1da9-a92fac16086d@enterprisedb.com
This commit is contained in:
Tom Lane 2017-07-20 15:28:42 -04:00
parent ed3dc224e5
commit 866f4a7c21
1 changed files with 37 additions and 29 deletions
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66
doc/src/sgml/release-10.sgml
View File

@ -151,6 +151,43 @@
<listitem>
<!--
2016-12-20 [1753b1b02] Add pg_sequence system catalog
2016-11-18 [67dc4ccbb] Add pg_sequences view
2017-05-15 [f8dc1985f] Fix ALTER SEQUENCE locking
2017-06-01 [3d79013b9] Make ALTER SEQUENCE, including RESTART, fully transactio
-->
<para>
Move sequences' metadata fields into a new <link
linkend="catalog-pg-sequence"><structname>pg_sequence</></>
system catalog (Peter Eisentraut)
</para>
<para>
A sequence relation now stores only the fields that can be modified
by <function>nextval()</>, that
is <structfield>last_value</>, <structfield>log_cnt</>,
and <structfield>is_called</>. Other sequence properties, such as
the starting value and increment, are kept in a corresponding row of
the <structname>pg_sequence</> catalog.
<command>ALTER SEQUENCE</> updates are now fully transactional,
implying that the sequence is locked until commit.
The <function>nextval()</> and <function>setval()</> functions
remain nontransactional.
</para>
<para>
The main incompatibility introduced by this change is that selecting
from a sequence relation now returns only the three fields named
above. To obtain the sequence's other properties, applications must
look into <structname>pg_sequence</>. The new system
view <link linkend="view-pg-sequences"><structname>pg_sequences</></>
can also be used for this purpose; it provides column names that are
more compatible with existing code.
</para>
</listitem>
<listitem>
<!--
2017-01-04 [9a4d51077] Make wal streaming the default mode for pg_basebackup
-->
<para>
@ -875,35 +912,6 @@
<listitem>
<!--
2016-12-20 [1753b1b02] Add pg_sequence system catalog
2016-11-18 [67dc4ccbb] Add pg_sequences view
2017-05-15 [f8dc1985f] Fix ALTER SEQUENCE locking
2017-06-01 [3d79013b9] Make ALTER SEQUENCE, including RESTART, fully transactio
-->
<para>
Create a <link
linkend="catalog-pg-sequence"><structname>pg_sequence</></>
system catalog to store sequence metadata (Peter Eisentraut)
</para>
<para>
Sequence metadata includes the start, increment, etc, properties.
<command>ALTER SEQUENCE</> updates are now fully transactional,
implying that the sequence is locked until commit. Sequences'
current values are still stored in individual table files, and
the <function>nextval()</> and <function>setval()</> functions
remain nontransactional.
</para>
<para>
Also
add <link linkend="view-pg-sequences"><structname>pg_sequences</></>
view to show all sequences.
</para>
</listitem>
<listitem>
<!--
2017-03-08 [f9b1a0dd4] Expose explain's SUMMARY option
-->
<para>