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<para>

Support for the SQL/XML standard, including new operators and a

new <type>XML</type>builtin type

Support for the SQL/XML standard, including new operators and

an <type>XML</type>data type

</para>

</listitem>

<listitem>

<para>

Universally Unique Identifier (<type>UUID</>) data type, similar

to that defined by RFC 4122

Universally Unique Identifier (<type>UUID</>) data type

</para>

</listitem>

<listitem>

<para>

<quote>Distributed</> checkpoints prevent I/O spikes during

checkpoints

Distributed checkpoints prevent I/O spikes during checkpoints

</para>

</listitem>

<listitem>

<para>

Heap-Only Tuples (<acronym>HOT</>)improves <command>UPDATE</>

spaceusage

Heap-Only Tuples (<acronym>HOT</>)accelerate <command>UPDATE</>

spacereuse

</para>

</listitem>

<listitem>

<para>

Just-in-time background writer strategyto improve disk write

Just-in-time background writer strategyimproves disk write

efficiency

</para>

</listitem>

<listitem>

<para>

Reduction ofbothper-field and per-row storage requirements

Reduction of per-field and per-row storage requirements

</para>

</listitem>

<listitem>

<para>

Use pseudo-transaction ids in read-only transactions

Reduce need for vacuum by using pseudo-transaction ids in

read-only transactions

</para>

</listitem>

<listitem>

<para>

<quote>Distributed</> checkpoints prevent I/O spikes during

Distributed checkpoints prevent I/O spikes during

checkpoints (Itagaki Takahiro and Heikki Linnakangas)

</para>

<listitem>

<para>

Heap-Only Tuples (<acronym>HOT</>)improves <command>UPDATE</>

spaceusage (Pavan Deolasee, with ideas from many others)

Heap-Only Tuples (<acronym>HOT</>)accelerate <command>UPDATE</>

spacereuse (Pavan Deolasee, with ideas from many others)

</para>

<para>

<listitem>

<para>

Just-in-time background writer strategyto improve disk write

Just-in-time background writer strategyimproves disk write

efficiency (Greg Smith, Itagaki Takahiro)

</para>

<listitem>

<para>

Reduction ofbothper-field and per-row storage requirements

(GregStark)

Reduction of per-field and per-row storage requirements (Greg

Stark)

</para>

<para>

<listitem>

<para>

Use pseudo-transaction ids in read-only transactions (Florian Pflug)

Reduce need for vacuum by using pseudo-transaction ids in

read-only transactions (Florian Pflug)

</para>

<para>

This reduces transaction overhead for read-only transactions,

and reduces the necessity of vacuuming for transaction id

wrap-around. Other transaction performance improvements were

also made that should improve concurrency.

Pseudo-transaction ids do not increment the global transaction

counter. Therefore, they do not add to the need for vacuum to

read all database rows to prevent problems with transaction id

wrap-around. Other transaction performance improvements were also

made that should improve concurrency.

</para>

</listitem>

<listitem>

<para>

Create a dedicated <acronym>WAL</> writer process to off-load

WAL-writingwork from backends (Simon)

work from backends (Simon)

</para>

</listitem>

</para>

</listitem>

<listitem>

<para>

Reduce overhead of populating the statistics tables. (Tom)

</para>

</listitem>

<listitem>

<para>

Allow <literal>ORDER BY ... LIMIT</> to be done without sorting

</para>

</listitem>

<listitem>

<para>

Reduce overhead of populating the statistics tables (Tom)

</para>

</listitem>

<listitem>

<para>

Improve hash join performance for cases with many NULLs (Tom)

<listitem>

<para>

Support for the SQL/XML standard, including new operators anda

new<type>XML</type>builtin type (Nikolay Samokhvalov, Peter)

Support for the SQL/XML standard, including new operators andan

<type>XML</type>data type (Nikolay Samokhvalov, Peter)

</para>

</listitem>

<listitem>

<para>

Universally Unique Identifier (<type>UUID</>) data type, similar

to that defined by RFC 4122 (Gevik Babakhani, Neil)

Universally Unique Identifier (<type>UUID</>) data type (Gevik

Babakhani, Neil)

</para>

<para>

This closely matches <acronym>RFC</> 4122.

</para>

</listitem>