<listitem>

<para>

Allow frequently uncontended locks to be recorded using a new

lightweight lock mechanism (Robert Haas)

fast-path lock mechanism (Robert Haas)

</para>

</listitem>

<para>

Add the <link linkend="SPGiST">SP-GiST</link> (Space-Partitioned

GiST) index access method (Teodor Sigaev, Oleg Bartunov, Tom

Lane, Robert Haas)

Lane)

</para>

<para>

<listitem>

<para>

Allow group commit to work effectively under heavy load (Peter

Geoghegan, Simon Riggs)

Geoghegan, Simon Riggs, Heikki Linnakangas)

</para>

<para>

<listitem>

<para>

Change "unexpected EOF" message to <literal>DEBUG1</> level

(Magnus Hagander)

Change "unexpected EOF" message to <literal>DEBUG1</> level,

except when there is an open transaction(Magnus Hagander)

</para>

</listitem>

<para>

Report checkpoint timing information in <link

linkend="pg-stat-bgwriter-view"><structname>pg_stat_bgwriter</></link>

(Greg Smith, Peter Geoghegan, Robert Haas)

(Greg Smith, Peter Geoghegan)

</para>

</listitem>

</para>

<para>

Thisonly writes data tothesocket, but does not wait a write

to the remote disk.

Thiswaits fortheremote server to acknowledge that it has received

the data, but does not wait for it to be writtento the remote disk.

</para>

</listitem>

Provide more reliable operation during concurrent

<acronym>DDL</acronym> (Robert Haas, Noah Misch)

</para>

<para>

This eliminates "cache lookup failed" errors in many scenarios.

Also, it is no longer possible to add relations to a schema which

is being concurrently dropped, a scenario that formerly led to

inconsistent system catalog contents.

</para>

</listitem>

<listitem>

constraints (Peter Eisentraut)

</para>

</listitem>

<listitem>

<para>

Disallow merging of <literal>ONLY</> and non-<literal>ONLY</>

constraints in child tables (Nikhil Sontakke)

</para>

<para>

Such merging would cause unpredictable behavior in grandchild

tables.

</para>

</listitem>

</itemizedlist>

</sect4>

<para>

Reduce need to rebuild tables and indexes for various <link

linkend="SQL-ALTERTABLE"><command>ALTER TABLE</command></link>

operations (Noah Misch) DUPLICATE?

operations (Noah Misch)

</para>

<para>

Increasing the length constraint on a <type>varchar</> or

<type>varbit</> column, or removing it altogether, no longer

requires a table rewrite. Increasing the allowable precision of

a <type>numeric</> constraint, or changing a column from constrained

<type>numeric</> to unconstrained numeric, no longer requires a

table rewrite. Table rewrites are also avoided in similar cases

involving the <type>interval</>, <type>timestamp</>, and

<type>timestamptz</> types.

</para>

</listitem>

<listitem>

<para>

Add <literal>IF EXIST</> clause to <command>ALTER</command>

Avoid having <link linkend="SQL-ALTERTABLE"><command>ALTER

TABLE</command></link> revalidate foreign key constraints in some

cases where it is not necessary (Noah Misch)

</para>

</listitem>

<listitem>

<para>

Add <literal>IF EXISTS</> clause to <command>ALTER</command>

commands (Pavel Stehule)

</para>

This also allows a table to be created whose schema matches a view.

</para>

</listitem>

<listitem>

<para>

Tighten creation of tables in temporary schemas (Robert Haas,

Amit Khandekar)

</para>

<para>

Previously, it was possible to create unlogged tables in temporary

schemas, and temporary tables in the temporary schemas of other

sessions.

</para>

</listitem>

</itemizedlist>

</sect4>

<para>

Add a <link

linkend="SQL-CREATEVIEW"><literal>security_barrier</></link>

option for views (KaiGai Kohei)

option for views (KaiGai Kohei, Robert Haas)

</para>

<para>

<listitem>

<para>

Add a <link linkend="datatype-json"><type>JSON</type></link>

data type (Robert Haas) AUTHOR?

data type (Robert Haas)

</para>

<para>