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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="RELEASE-9-6"
>E.18. Release 9.6</A
></H1
><DIV
CLASS="FORMALPARA"
><P
><B
>Release date: </B
>2016-09-29</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN134293"
>E.18.1. Overview</A
></H2
><P
> Major enhancements in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> 9.6 include:
</P
><P
></P
><UL
><LI
><P
> Parallel execution of sequential scans, joins and aggregates
</P
></LI
><LI
><P
> Avoid scanning pages unnecessarily during vacuum freeze operations
</P
></LI
><LI
><P
> Synchronous replication now allows multiple standby servers for
increased reliability
</P
></LI
><LI
><P
> Full-text search can now search for phrases (multiple adjacent words)
</P
></LI
><LI
><P
> <TT
CLASS="FILENAME"
>postgres_fdw</TT
> now supports remote joins, sorts,
<TT
CLASS="COMMAND"
>UPDATE</TT
>s, and <TT
CLASS="COMMAND"
>DELETE</TT
>s
</P
></LI
><LI
><P
> Substantial performance improvements, especially in the area of
scalability on multi-<ACRONYM
CLASS="ACRONYM"
>CPU</ACRONYM
>-socket servers
</P
></LI
></UL
><P
> The above items are explained in more detail in the sections below.
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN134315"
>E.18.2. Migration to Version 9.6</A
></H2
><P
> A dump/restore using <A
HREF="app-pg-dumpall.html"
><SPAN
CLASS="APPLICATION"
>pg_dumpall</SPAN
></A
>, or use of <A
HREF="pgupgrade.html"
><SPAN
CLASS="APPLICATION"
>pg_upgrade</SPAN
></A
>, is required for those wishing to migrate data
from any previous release.
</P
><P
> Version 9.6 contains a number of changes that may affect compatibility
with previous releases. Observe the following incompatibilities:
</P
><P
></P
><UL
><LI
><P
> Improve the <A
HREF="monitoring-stats.html#PG-STAT-ACTIVITY-VIEW"
><TT
CLASS="STRUCTNAME"
>pg_stat_activity</TT
></A
>
view's information about what a process is waiting for (Amit
Kapila, Ildus Kurbangaliev)
</P
><P
> Historically a process has only been shown as waiting if it was
waiting for a heavyweight lock. Now waits for lightweight locks
and buffer pins are also shown in <TT
CLASS="STRUCTNAME"
>pg_stat_activity</TT
>.
Also, the type of lock being waited for is now visible.
These changes replace the <TT
CLASS="STRUCTFIELD"
>waiting</TT
> column with
<TT
CLASS="STRUCTFIELD"
>wait_event_type</TT
> and <TT
CLASS="STRUCTFIELD"
>wait_event</TT
>.
</P
></LI
><LI
><P
> In <A
HREF="functions-formatting.html#FUNCTIONS-FORMATTING-TABLE"
><CODE
CLASS="FUNCTION"
>to_char()</CODE
></A
>,
do not count a minus sign (when needed) as part of the field
width for time-related fields (Bruce Momjian)
</P
><P
> For example, <TT
CLASS="LITERAL"
>to_char('-4 years'::interval, 'YY')</TT
>
now returns <TT
CLASS="LITERAL"
>-04</TT
>, rather than <TT
CLASS="LITERAL"
>-4</TT
>.
</P
></LI
><LI
><P
> Make <A
HREF="functions-datetime.html#FUNCTIONS-DATETIME-TABLE"
><CODE
CLASS="FUNCTION"
>extract()</CODE
></A
> behave
more reasonably with infinite inputs (Vitaly Burovoy)
</P
><P
> Historically the <CODE
CLASS="FUNCTION"
>extract()</CODE
> function just returned
zero given an infinite timestamp, regardless of the given
field name. Make it return <TT
CLASS="LITERAL"
>infinity</TT
>
or <TT
CLASS="LITERAL"
>-infinity</TT
> as appropriate when the
requested field is one that is monotonically increasing (e.g,
<TT
CLASS="LITERAL"
>year</TT
>, <TT
CLASS="LITERAL"
>epoch</TT
>), or <TT
CLASS="LITERAL"
>NULL</TT
> when
it is not (e.g., <TT
CLASS="LITERAL"
>day</TT
>, <TT
CLASS="LITERAL"
>hour</TT
>). Also,
throw the expected error for bad field names.
</P
></LI
><LI
><P
> Remove PL/pgSQL's <SPAN
CLASS="QUOTE"
>"feature"</SPAN
> that suppressed the
innermost line of <TT
CLASS="LITERAL"
>CONTEXT</TT
> for messages emitted by
<TT
CLASS="COMMAND"
>RAISE</TT
> commands (Pavel Stehule)
</P
><P
> This ancient backwards-compatibility hack was agreed to have
outlived its usefulness.
</P
></LI
><LI
><P
> Fix the default text search parser to allow leading digits
in <TT
CLASS="LITERAL"
>email</TT
> and <TT
CLASS="LITERAL"
>host</TT
> tokens (Artur Zakirov)
</P
><P
> In most cases this will result in few changes in the parsing of
text. But if you have data where such addresses occur frequently,
it may be worth rebuilding dependent <TT
CLASS="TYPE"
>tsvector</TT
> columns
and indexes so that addresses of this form will be found properly
by text searches.
</P
></LI
><LI
><P
> Extend <A
HREF="unaccent.html"
><TT
CLASS="FILENAME"
>contrib/unaccent</TT
></A
>'s
standard <TT
CLASS="FILENAME"
>unaccent.rules</TT
> file to handle all diacritics
known to Unicode, and to expand ligatures correctly (Thomas Munro,
Léonard Benedetti)
</P
><P
> The previous version neglected to convert some less-common letters
with diacritic marks. Also, ligatures are now expanded into
separate letters. Installations that use this rules file may wish
to rebuild <TT
CLASS="TYPE"
>tsvector</TT
> columns and indexes that depend on the
result.
</P
></LI
><LI
><P
> Remove the long-deprecated
<TT
CLASS="LITERAL"
>CREATEUSER</TT
>/<TT
CLASS="LITERAL"
>NOCREATEUSER</TT
> options from
<TT
CLASS="COMMAND"
>CREATE ROLE</TT
> and allied commands (Tom Lane)
</P
><P
> <TT
CLASS="LITERAL"
>CREATEUSER</TT
> actually meant <TT
CLASS="LITERAL"
>SUPERUSER</TT
>,
for ancient backwards-compatibility reasons. This has been a
constant source of confusion for people who (reasonably) expect
it to mean <TT
CLASS="LITERAL"
>CREATEROLE</TT
>. It has been deprecated for
ten years now, so fix the problem by removing it.
</P
></LI
><LI
><P
> Treat role names beginning with <TT
CLASS="LITERAL"
>pg_</TT
> as reserved
(Stephen Frost)
</P
><P
> User creation of such role names is now disallowed. This prevents
conflicts with built-in roles created by <SPAN
CLASS="APPLICATION"
>initdb</SPAN
>.
</P
></LI
><LI
><P
> Change a column name in the
<TT
CLASS="STRUCTNAME"
>information_schema</TT
>.<TT
CLASS="STRUCTNAME"
>routines</TT
>
view from <TT
CLASS="STRUCTFIELD"
>result_cast_character_set_name</TT
>
to <TT
CLASS="STRUCTFIELD"
>result_cast_char_set_name</TT
> (Clément
Prévost)
</P
><P
> The SQL:2011 standard specifies the longer name, but that appears
to be a mistake, because adjacent column names use the shorter
style, as do other <TT
CLASS="STRUCTNAME"
>information_schema</TT
> views.
</P
></LI
><LI
><P
> <SPAN
CLASS="APPLICATION"
>psql</SPAN
>'s <TT
CLASS="OPTION"
>-c</TT
> option no longer implies
<TT
CLASS="OPTION"
>--no-psqlrc</TT
>
(Pavel Stehule, Catalin Iacob)
</P
><P
> Write <TT
CLASS="OPTION"
>--no-psqlrc</TT
> (or its
abbreviation <TT
CLASS="OPTION"
>-X</TT
>) explicitly to obtain the old
behavior. Scripts so modified will still work with old
versions of <SPAN
CLASS="APPLICATION"
>psql</SPAN
>.
</P
></LI
><LI
><P
> Improve <SPAN
CLASS="APPLICATION"
>pg_restore</SPAN
>'s <TT
CLASS="OPTION"
>-t</TT
> option to
match all types of relations, not only plain tables (Craig Ringer)
</P
></LI
><LI
><P
> Change the display format used for <TT
CLASS="LITERAL"
>NextXID</TT
> in
<SPAN
CLASS="APPLICATION"
>pg_controldata</SPAN
> and related places (Joe Conway,
Bruce Momjian)
</P
><P
> Display epoch-and-transaction-ID values in the format
<TT
CLASS="REPLACEABLE"
><I
>number</I
></TT
><TT
CLASS="LITERAL"
>:</TT
><TT
CLASS="REPLACEABLE"
><I
>number</I
></TT
>.
The previous format
<TT
CLASS="REPLACEABLE"
><I
>number</I
></TT
><TT
CLASS="LITERAL"
>/</TT
><TT
CLASS="REPLACEABLE"
><I
>number</I
></TT
> was
confusingly similar to that used for <ACRONYM
CLASS="ACRONYM"
>LSN</ACRONYM
>s.
</P
></LI
><LI
><P
> Update extension functions to be marked parallel-safe where
appropriate (Andreas Karlsson)
</P
><P
> Many of the standard extensions have been updated to allow their
functions to be executed within parallel query worker processes.
These changes will not take effect in
databases <SPAN
CLASS="APPLICATION"
>pg_upgrade</SPAN
>'d from prior versions unless
you apply <TT
CLASS="COMMAND"
>ALTER EXTENSION UPDATE</TT
> to each such extension
(in each database of a cluster).
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN134423"
>E.18.3. Changes</A
></H2
><P
> Below you will find a detailed account of the changes between
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> 9.6 and the previous major
release.
</P
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN134427"
>E.18.3.1. Server</A
></H3
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134429"
>E.18.3.1.1. Parallel Queries</A
></H4
><P
></P
><UL
><LI
><P
> Parallel queries (Robert Haas, Amit Kapila, David Rowley,
many others)
</P
><P
> With 9.6, <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> introduces initial support
for parallel execution of large queries. Only strictly read-only
queries where the driving table is accessed via a sequential scan
can be parallelized. Hash joins and nested loops can be performed
in parallel, as can aggregation (for supported aggregates).
Much remains to be done, but this is already a useful set of
features.
</P
><P
> Parallel query execution is not (yet) enabled by default.
To allow it, set the new configuration
parameter <A
HREF="runtime-config-resource.html#GUC-MAX-PARALLEL-WORKERS-PER-GATHER"
>max_parallel_workers_per_gather</A
> to a
value larger than zero. Additional control over use of parallelism
is available through other new configuration parameters
<A
HREF="runtime-config-query.html#GUC-FORCE-PARALLEL-MODE"
>force_parallel_mode</A
>,
<A
HREF="runtime-config-query.html#GUC-PARALLEL-SETUP-COST"
>parallel_setup_cost</A
>, <A
HREF="runtime-config-query.html#GUC-PARALLEL-TUPLE-COST"
>parallel_tuple_cost</A
>, and <A
HREF="runtime-config-query.html#GUC-MIN-PARALLEL-RELATION-SIZE"
>min_parallel_relation_size</A
>.
</P
></LI
><LI
><P
> Provide infrastructure for marking the parallel-safety status of
functions (Robert Haas, Amit Kapila)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134444"
>E.18.3.1.2. Indexes</A
></H4
><P
></P
><UL
><LI
><P
> Allow <A
HREF="gin.html"
><ACRONYM
CLASS="ACRONYM"
>GIN</ACRONYM
></A
> index builds to
make effective use of <A
HREF="runtime-config-resource.html#GUC-MAINTENANCE-WORK-MEM"
>maintenance_work_mem</A
>
settings larger than 1 GB (Robert Abraham, Teodor Sigaev)
</P
></LI
><LI
><P
> Add pages deleted from a GIN index's pending list to the free space
map immediately
(Jeff Janes, Teodor Sigaev)
</P
><P
> This reduces bloat if the table is not vacuumed often.
</P
></LI
><LI
><P
> Add <A
HREF="functions-admin.html#FUNCTIONS-ADMIN-INDEX"
><CODE
CLASS="FUNCTION"
>gin_clean_pending_list()</CODE
></A
>
function to allow manual invocation of pending-list cleanup for a
GIN index (Jeff Janes)
</P
><P
> Formerly, such cleanup happened only as a byproduct of vacuuming or
analyzing the parent table.
</P
></LI
><LI
><P
> Improve handling of dead index tuples in <A
HREF="gist.html"
>GiST</A
> indexes (Anastasia Lubennikova)
</P
><P
> Dead index tuples are now marked as such when an index scan notices
that the corresponding heap tuple is dead. When inserting tuples,
marked-dead tuples will be removed if needed to make space on
the page.
</P
></LI
><LI
><P
> Add an <A
HREF="spgist.html"
>SP-GiST</A
> operator class for
type <TT
CLASS="TYPE"
>box</TT
> (Alexander Lebedev)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134468"
>E.18.3.1.3. Sorting</A
></H4
><P
></P
><UL
><LI
><P
> Improve sorting performance by using quicksort, not replacement
selection sort, when performing external sort steps (Peter
Geoghegan)
</P
><P
> The new approach makes better use of the <ACRONYM
CLASS="ACRONYM"
>CPU</ACRONYM
> cache
for typical cache sizes and data volumes. Where necessary,
the behavior can be adjusted via the new configuration parameter
<A
HREF="runtime-config-resource.html#GUC-REPLACEMENT-SORT-TUPLES"
>replacement_sort_tuples</A
>.
</P
></LI
><LI
><P
> Speed up text sorts where the same string occurs multiple times
(Peter Geoghegan)
</P
></LI
><LI
><P
> Speed up sorting of <TT
CLASS="TYPE"
>uuid</TT
>, <TT
CLASS="TYPE"
>bytea</TT
>, and
<TT
CLASS="TYPE"
>char(n)</TT
> fields by using <SPAN
CLASS="QUOTE"
>"abbreviated"</SPAN
> keys
(Peter Geoghegan)
</P
><P
> Support for abbreviated keys has also been
added to the non-default operator classes <A
HREF="indexes-opclass.html"
><TT
CLASS="LITERAL"
>text_pattern_ops</TT
></A
>,
<TT
CLASS="LITERAL"
>varchar_pattern_ops</TT
>, and
<TT
CLASS="LITERAL"
>bpchar_pattern_ops</TT
>. Processing of ordered-set
aggregates can also now exploit abbreviated keys.
</P
></LI
><LI
><P
> Speed up <TT
CLASS="COMMAND"
>CREATE INDEX CONCURRENTLY</TT
> by treating
<ACRONYM
CLASS="ACRONYM"
>TID</ACRONYM
>s as 64-bit integers during sorting (Peter
Geoghegan)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134493"
>E.18.3.1.4. Locking</A
></H4
><P
></P
><UL
><LI
><P
> Reduce contention for the <TT
CLASS="LITERAL"
>ProcArrayLock</TT
> (Amit Kapila,
Robert Haas)
</P
></LI
><LI
><P
> Improve performance by moving buffer content locks into the buffer
descriptors (Andres Freund, Simon Riggs)
</P
></LI
><LI
><P
> Replace shared-buffer header spinlocks with atomic operations to
improve scalability (Alexander Korotkov, Andres Freund)
</P
></LI
><LI
><P
> Use atomic operations, rather than a spinlock, to protect an
<TT
CLASS="LITERAL"
>LWLock</TT
>'s wait queue (Andres Freund)
</P
></LI
><LI
><P
> Partition the shared hash table freelist to reduce contention on
multi-<ACRONYM
CLASS="ACRONYM"
>CPU</ACRONYM
>-socket servers (Aleksander Alekseev)
</P
></LI
><LI
><P
> Reduce interlocking on standby servers during the replay of btree
index vacuuming operations (Simon Riggs)
</P
><P
> This change avoids substantial replication delays that sometimes
occurred while replaying such operations.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134512"
>E.18.3.1.5. Optimizer Statistics</A
></H4
><P
></P
><UL
><LI
><P
> Improve <TT
CLASS="COMMAND"
>ANALYZE</TT
>'s estimates for columns with many nulls
(Tomas Vondra, Alex Shulgin)
</P
><P
> Previously <TT
CLASS="COMMAND"
>ANALYZE</TT
> tended to underestimate the number
of non-<TT
CLASS="LITERAL"
>NULL</TT
> distinct values in a column with many
<TT
CLASS="LITERAL"
>NULL</TT
>s, and was also inaccurate in computing the
most-common values.
</P
></LI
><LI
><P
> Improve planner's estimate of the number of distinct values in
a query result (Tomas Vondra)
</P
></LI
><LI
><P
> Use foreign key relationships to infer selectivity for join
predicates (Tomas Vondra, David Rowley)
</P
><P
> If a table <TT
CLASS="LITERAL"
>t</TT
> has a foreign key restriction, say
<TT
CLASS="LITERAL"
>(a,b) REFERENCES r (x,y)</TT
>, then a <TT
CLASS="LITERAL"
>WHERE</TT
>
condition such as <TT
CLASS="LITERAL"
>t.a = r.x AND t.b = r.y</TT
> cannot
select more than one <TT
CLASS="LITERAL"
>r</TT
> row per <TT
CLASS="LITERAL"
>t</TT
> row.
The planner formerly considered these <TT
CLASS="LITERAL"
>AND</TT
> conditions
to be independent and would often drastically misestimate
selectivity as a result. Now it compares the <TT
CLASS="LITERAL"
>WHERE</TT
>
conditions to applicable foreign key constraints and produces
better estimates.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134535"
>E.18.3.1.6. <TT
CLASS="COMMAND"
>VACUUM</TT
></A
></H4
><P
></P
><UL
><LI
><P
> Avoid re-vacuuming pages containing only frozen tuples (Masahiko
Sawada, Robert Haas, Andres Freund)
</P
><P
> Formerly, anti-wraparound vacuum had to visit every page of
a table, even pages where there was nothing to do. Now, pages
containing only already-frozen tuples are identified in the table's
visibility map, and can be skipped by vacuum even when doing
transaction wraparound prevention. This should greatly reduce the
cost of maintaining large tables containing mostly-unchanging data.
</P
><P
> If necessary, vacuum can be forced to process all-frozen
pages using the new <TT
CLASS="LITERAL"
>DISABLE_PAGE_SKIPPING</TT
> option.
Normally this should never be needed, but it might help in
recovering from visibility-map corruption.
</P
></LI
><LI
><P
> Avoid useless heap-truncation attempts during <TT
CLASS="COMMAND"
>VACUUM</TT
>
(Jeff Janes, Tom Lane)
</P
><P
> This change avoids taking an exclusive table lock in some cases
where no truncation is possible. The main benefit comes from
avoiding unnecessary query cancellations on standby servers.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134548"
>E.18.3.1.7. General Performance</A
></H4
><P
></P
><UL
><LI
><P
> Allow old <ACRONYM
CLASS="ACRONYM"
>MVCC</ACRONYM
> snapshots to be invalidated after a
configurable timeout (Kevin Grittner)
</P
><P
> Normally, deleted tuples cannot be physically removed by
vacuuming until the last transaction that could <SPAN
CLASS="QUOTE"
>"see"</SPAN
>
them is gone. A transaction that stays open for a long
time can thus cause considerable table bloat because
space cannot be recycled. This feature allows setting
a time-based limit, via the new configuration parameter
<A
HREF="runtime-config-resource.html#GUC-OLD-SNAPSHOT-THRESHOLD"
>old_snapshot_threshold</A
>, on how long an
<ACRONYM
CLASS="ACRONYM"
>MVCC</ACRONYM
> snapshot is guaranteed to be valid. After that,
dead tuples are candidates for removal. A transaction using an
outdated snapshot will get an error if it attempts to read a page
that potentially could have contained such data.
</P
></LI
><LI
><P
> Ignore <TT
CLASS="LITERAL"
>GROUP BY</TT
> columns that are
functionally dependent on other columns (David Rowley)
</P
><P
> If a <TT
CLASS="LITERAL"
>GROUP BY</TT
> clause includes all columns of a
non-deferred primary key, as well as other columns of the same
table, those other columns are redundant and can be dropped
from the grouping. This saves computation in many common cases.
</P
></LI
><LI
><P
> Allow use of an <A
HREF="indexes-index-only-scans.html"
>index-only
scan</A
> on a partial index when the index's <TT
CLASS="LITERAL"
>WHERE</TT
>
clause references columns that are not indexed (Tomas Vondra,
Kyotaro Horiguchi)
</P
><P
> For example, an index defined by <TT
CLASS="COMMAND"
>CREATE INDEX tidx_partial
ON t(b) WHERE a > 0</TT
> can now be used for an index-only scan by
a query that specifies <TT
CLASS="LITERAL"
>WHERE a > 0</TT
> and does not
otherwise use <TT
CLASS="LITERAL"
>a</TT
>. Previously this was disallowed
because <TT
CLASS="LITERAL"
>a</TT
> is not listed as an index column.
</P
></LI
><LI
><P
> Perform checkpoint writes in sorted order (Fabien Coelho,
Andres Freund)
</P
><P
> Previously, checkpoints wrote out dirty pages in whatever order
they happen to appear in shared buffers, which usually is nearly
random. That performs poorly, especially on rotating media.
This change causes checkpoint-driven writes to be done in order
by file and block number, and to be balanced across tablespaces.
</P
></LI
><LI
><P
> Where feasible, trigger kernel writeback after a configurable
number of writes, to prevent accumulation of dirty data in kernel
disk buffers (Fabien Coelho, Andres Freund)
</P
><P
> <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> writes data to the kernel's disk cache,
from where it will be flushed to physical storage in due time.
Many operating systems are not smart about managing this and allow
large amounts of dirty data to accumulate before deciding to flush
it all at once, causing long delays for new I/O requests until the
flushing finishes.
This change attempts to alleviate this problem by explicitly
requesting data flushes after a configurable interval.
</P
><P
> On Linux, <CODE
CLASS="FUNCTION"
>sync_file_range()</CODE
> is used for this purpose,
and the feature is on by default on Linux because that function has
few downsides. This flushing capability is also available on other
platforms if they have <CODE
CLASS="FUNCTION"
>msync()</CODE
>
or <CODE
CLASS="FUNCTION"
>posix_fadvise()</CODE
>, but those interfaces have some
undesirable side-effects so the feature is disabled by default on
non-Linux platforms.
</P
><P
> The new configuration parameters <A
HREF="runtime-config-resource.html#GUC-BACKEND-FLUSH-AFTER"
>backend_flush_after</A
>, <A
HREF="runtime-config-resource.html#GUC-BGWRITER-FLUSH-AFTER"
>bgwriter_flush_after</A
>, <A
HREF="runtime-config-wal.html#GUC-CHECKPOINT-FLUSH-AFTER"
>checkpoint_flush_after</A
>, and <A
HREF="runtime-config-wal.html#GUC-WAL-WRITER-FLUSH-AFTER"
>wal_writer_flush_after</A
> control this behavior.
</P
></LI
><LI
><P
> Improve aggregate-function performance by sharing calculations
across multiple aggregates if they have the same arguments and
transition functions (David Rowley)
</P
><P
> For example, <TT
CLASS="COMMAND"
>SELECT AVG(x), VARIANCE(x) FROM tab</TT
> can use
a single per-row computation for both aggregates.
</P
></LI
><LI
><P
> Speed up visibility tests for recently-created tuples by checking
the current transaction's snapshot, not <TT
CLASS="STRUCTNAME"
>pg_clog</TT
>, to
decide if the source transaction should be considered committed
(Jeff Janes, Tom Lane)
</P
></LI
><LI
><P
> Allow tuple hint bits to be set sooner than before (Andres Freund)
</P
></LI
><LI
><P
> Improve performance of short-lived prepared transactions (Stas
Kelvich, Simon Riggs, Pavan Deolasee)
</P
><P
> Two-phase commit information is now written only to <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
>
during <TT
CLASS="COMMAND"
>PREPARE TRANSACTION</TT
>, and will be read back from
<ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> during <TT
CLASS="COMMAND"
>COMMIT PREPARED</TT
> if that happens
soon thereafter. A separate state file is created only if the
pending transaction does not get committed or aborted by the time
of the next checkpoint.
</P
></LI
><LI
><P
> Improve performance of memory context destruction (Jan Wieck)
</P
></LI
><LI
><P
> Improve performance of resource owners with many tracked objects
(Aleksander Alekseev)
</P
></LI
><LI
><P
> Improve speed of the output functions for <TT
CLASS="TYPE"
>timestamp</TT
>,
<TT
CLASS="TYPE"
>time</TT
>, and <TT
CLASS="TYPE"
>date</TT
> data types (David Rowley,
Andres Freund)
</P
></LI
><LI
><P
> Avoid some unnecessary cancellations of hot-standby queries
during replay of actions that take <TT
CLASS="LITERAL"
>AccessExclusive</TT
>
locks (Jeff Janes)
</P
></LI
><LI
><P
> Extend relations multiple blocks at a time when there is contention
for the relation's extension lock (Dilip Kumar)
</P
><P
> This improves scalability by decreasing contention.
</P
></LI
><LI
><P
> Increase the number of clog buffers for better scalability (Amit
Kapila, Andres Freund)
</P
></LI
><LI
><P
> Speed up expression evaluation in <SPAN
CLASS="APPLICATION"
>PL/pgSQL</SPAN
> by
keeping <TT
CLASS="LITERAL"
>ParamListInfo</TT
> entries for simple variables
valid at all times (Tom Lane)
</P
></LI
><LI
><P
> Avoid reducing the <TT
CLASS="LITERAL"
>SO_SNDBUF</TT
> setting below its default
on recent Windows versions (Chen Huajun)
</P
></LI
><LI
><P
> Disable <A
HREF="runtime-config-logging.html#GUC-UPDATE-PROCESS-TITLE"
>update_process_title</A
> by default on
Windows (Takayuki Tsunakawa)
</P
><P
> The overhead of updating the process title is much larger on Windows
than most other platforms, and it is also less useful to do it since
most Windows users do not have tools that can display process titles.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134632"
>E.18.3.1.8. Monitoring</A
></H4
><P
></P
><UL
><LI
><P
> Add <A
HREF="progress-reporting.html#PG-STAT-PROGRESS-VACUUM-VIEW"
><TT
CLASS="STRUCTNAME"
>pg_stat_progress_vacuum</TT
></A
>
system view to provide progress reporting for <TT
CLASS="COMMAND"
>VACUUM</TT
>
operations (Amit Langote, Robert Haas, Vinayak Pokale, Rahila Syed)
</P
></LI
><LI
><P
> Add <A
HREF="functions-info.html#FUNCTIONS-CONTROLDATA"
><CODE
CLASS="FUNCTION"
>pg_control_system()</CODE
></A
>,
<CODE
CLASS="FUNCTION"
>pg_control_checkpoint()</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_control_recovery()</CODE
>, and
<CODE
CLASS="FUNCTION"
>pg_control_init()</CODE
> functions to expose fields of
<TT
CLASS="FILENAME"
>pg_control</TT
> to <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> (Joe Conway, Michael
Paquier)
</P
></LI
><LI
><P
> Add <A
HREF="view-pg-config.html"
><TT
CLASS="STRUCTNAME"
>pg_config</TT
></A
>
system view (Joe Conway)
</P
><P
> This view exposes the same information available from
the <SPAN
CLASS="APPLICATION"
>pg_config</SPAN
> command-line utility,
namely assorted compile-time configuration information for
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>.
</P
></LI
><LI
><P
> Add a <TT
CLASS="STRUCTFIELD"
>confirmed_flush_lsn</TT
> column to the <A
HREF="view-pg-replication-slots.html"
><TT
CLASS="STRUCTNAME"
>pg_replication_slots</TT
></A
>
system view (Marko Tiikkaja)
</P
></LI
><LI
><P
> Add <A
HREF="monitoring-stats.html#PG-STAT-WAL-RECEIVER-VIEW"
><TT
CLASS="STRUCTNAME"
>pg_stat_wal_receiver</TT
></A
>
system view to provide information about the state of a hot-standby
server's <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> receiver process (Michael Paquier)
</P
></LI
><LI
><P
> Add <A
HREF="functions-info.html#FUNCTIONS-INFO-SESSION-TABLE"
><CODE
CLASS="FUNCTION"
>pg_blocking_pids()</CODE
></A
>
function to reliably identify which sessions block which others
(Tom Lane)
</P
><P
> This function returns an array of the process IDs of any
sessions that are blocking the session with the given process ID.
Historically users have obtained such information using a self-join
on the <TT
CLASS="STRUCTNAME"
>pg_locks</TT
> view. However, it is unreasonably
tedious to do it that way with any modicum of correctness, and
the addition of parallel queries has made the old approach entirely
impractical, since locks might be held or awaited by child worker
processes rather than the session's main process.
</P
></LI
><LI
><P
> Add function <A
HREF="functions-admin.html#FUNCTIONS-ADMIN-BACKUP-TABLE"
><CODE
CLASS="FUNCTION"
>pg_current_xlog_flush_location()</CODE
></A
>
to expose the current transaction log flush location (Tomas Vondra)
</P
></LI
><LI
><P
> Add function <A
HREF="functions-info.html#FUNCTIONS-INFO-SESSION-TABLE"
><CODE
CLASS="FUNCTION"
>pg_notification_queue_usage()</CODE
></A
>
to report how full the <TT
CLASS="COMMAND"
>NOTIFY</TT
> queue is (Brendan Jurd)
</P
></LI
><LI
><P
> Limit the verbosity of memory context statistics dumps (Tom Lane)
</P
><P
> The memory usage dump that is output to the postmaster log during an
out-of-memory failure now summarizes statistics when there are a
large number of memory contexts, rather than possibly generating
a very large report. There is also a <SPAN
CLASS="QUOTE"
>"grand total"</SPAN
>
summary line now.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134685"
>E.18.3.1.9. <ACRONYM
CLASS="ACRONYM"
>Authentication</ACRONYM
></A
></H4
><P
></P
><UL
><LI
><P
> Add a <A
HREF="auth-methods.html#AUTH-BSD"
><ACRONYM
CLASS="ACRONYM"
>BSD</ACRONYM
> authentication
method</A
> to allow use of
the <SPAN
CLASS="SYSTEMITEM"
>BSD</SPAN
> Authentication service for
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> client authentication (Marisa Emerson)
</P
><P
> BSD Authentication is currently only available on <SPAN
CLASS="SYSTEMITEM"
>OpenBSD</SPAN
>.
</P
></LI
><LI
><P
> When using <A
HREF="auth-methods.html#AUTH-PAM"
><ACRONYM
CLASS="ACRONYM"
>PAM</ACRONYM
>
authentication</A
>, provide the client IP address or host name
to <ACRONYM
CLASS="ACRONYM"
>PAM</ACRONYM
> modules via the <TT
CLASS="LITERAL"
>PAM_RHOST</TT
> item
(Grzegorz Sampolski)
</P
></LI
><LI
><P
> Provide detail in the postmaster log for more types of password
authentication failure (Tom Lane)
</P
><P
> All ordinarily-reachable password authentication failure cases
should now provide specific <TT
CLASS="LITERAL"
>DETAIL</TT
> fields in the log.
</P
></LI
><LI
><P
> Support <A
HREF="auth-methods.html#AUTH-RADIUS"
><ACRONYM
CLASS="ACRONYM"
>RADIUS</ACRONYM
> passwords</A
>
up to 128 characters long (Marko Tiikkaja)
</P
></LI
><LI
><P
> Add new <A
HREF="auth-methods.html#SSPI-AUTH"
><ACRONYM
CLASS="ACRONYM"
>SSPI</ACRONYM
>
authentication</A
> parameters
<TT
CLASS="VARNAME"
>compat_realm</TT
> and <TT
CLASS="VARNAME"
>upn_username</TT
> to control
whether <SPAN
CLASS="PRODUCTNAME"
>NetBIOS</SPAN
> or <SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
>
realm names and user names are used during <ACRONYM
CLASS="ACRONYM"
>SSPI</ACRONYM
>
authentication (Christian Ullrich)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134720"
>E.18.3.1.10. Server Configuration</A
></H4
><P
></P
><UL
><LI
><P
> Allow sessions to be terminated automatically if they are in
idle-in-transaction state for too long (Vik Fearing)
</P
><P
> This behavior is controlled by the new configuration parameter
<A
HREF="runtime-config-client.html#GUC-IDLE-IN-TRANSACTION-SESSION-TIMEOUT"
>idle_in_transaction_session_timeout</A
>. It can
be useful to prevent forgotten transactions from holding locks
or preventing vacuum cleanup for too long.
</P
></LI
><LI
><P
> Raise the maximum allowed value
of <A
HREF="runtime-config-wal.html#GUC-CHECKPOINT-TIMEOUT"
>checkpoint_timeout</A
> to 24 hours (Simon Riggs)
</P
></LI
><LI
><P
> Allow <TT
CLASS="VARNAME"
>effective_io_concurrency</TT
> to be set per-tablespace
to support cases where different tablespaces have different I/O
characteristics (Julien Rouhaud)
</P
></LI
><LI
><P
> Add <A
HREF="runtime-config-logging.html#GUC-LOG-LINE-PREFIX"
>log_line_prefix</A
> option <TT
CLASS="LITERAL"
>%n</TT
> to
print the current time in Unix epoch form, with milliseconds (Tomas
Vondra, Jeff Davis)
</P
></LI
><LI
><P
> Add <A
HREF="runtime-config-logging.html#GUC-SYSLOG-SEQUENCE-NUMBERS"
>syslog_sequence_numbers</A
> and <A
HREF="runtime-config-logging.html#GUC-SYSLOG-SPLIT-MESSAGES"
>syslog_split_messages</A
> configuration parameters
to provide more control over the message format when logging to
<SPAN
CLASS="SYSTEMITEM"
>syslog</SPAN
> (Peter Eisentraut)
</P
></LI
><LI
><P
> Merge the <TT
CLASS="LITERAL"
>archive</TT
> and <TT
CLASS="LITERAL"
>hot_standby</TT
> values
of the <A
HREF="runtime-config-wal.html#GUC-WAL-LEVEL"
>wal_level</A
> configuration parameter
into a single new value <TT
CLASS="LITERAL"
>replica</TT
> (Peter Eisentraut)
</P
><P
> Making a distinction between these settings is no longer useful,
and merging them is a step towards a planned future simplification
of replication setup. The old names are still accepted but are
converted to <TT
CLASS="LITERAL"
>replica</TT
> internally.
</P
></LI
><LI
><P
> Add configure option <TT
CLASS="OPTION"
>--with-systemd</TT
> to enable
calling <CODE
CLASS="FUNCTION"
>sd_notify()</CODE
> at server start and stop (Peter
Eisentraut)
</P
><P
> This allows the use of <SPAN
CLASS="APPLICATION"
>systemd</SPAN
> service units of
type <TT
CLASS="LITERAL"
>notify</TT
>, which greatly simplifies the management
of <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> under <SPAN
CLASS="APPLICATION"
>systemd</SPAN
>.
</P
></LI
><LI
><P
> Allow the server's <ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
> key file to have group read
access if it is owned by <TT
CLASS="LITERAL"
>root</TT
> (Christoph Berg)
</P
><P
> Formerly, we insisted the key file be owned by the
user running the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> server, but
that is inconvenient on some systems (such as <SPAN
CLASS="SYSTEMITEM"
>Debian</SPAN
>) that are configured to manage
certificates centrally. Therefore, allow the case where the key
file is owned by <TT
CLASS="LITERAL"
>root</TT
> and has group read access.
It is up to the operating system administrator to ensure that
the group does not include any untrusted users.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN134767"
>E.18.3.1.11. Reliability</A
></H4
><P
></P
><UL
><LI
><P
> Force backends to exit if the postmaster dies (Rajeev Rastogi,
Robert Haas)
</P
><P
> Under normal circumstances the postmaster should always outlive
its child processes. If for some reason the postmaster dies,
force backend sessions to exit with an error. Formerly, existing
backends would continue to run until their clients disconnect,
but that is unsafe and inefficient. It also prevents a new
postmaster from being started until the last old backend has
exited. Backends will detect postmaster death when waiting for
client I/O, so the exit will not be instantaneous, but it should
happen no later than the end of the current query.
</P
></LI
><LI
><P
> Check for serializability conflicts before reporting
constraint-violation failures (Thomas Munro)
</P
><P
> When using serializable transaction isolation, it is desirable
that any error due to concurrent transactions should manifest
as a serialization failure, thereby cueing the application that
a retry might succeed. Unfortunately, this does not reliably
happen for duplicate-key failures caused by concurrent insertions.
This change ensures that such an error will be reported as a
serialization error if the application explicitly checked for
the presence of a conflicting key (and did not find it) earlier
in the transaction.
</P
></LI
><LI
><P
> Ensure that invalidation messages are recorded in <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
>
even when issued by a transaction that has no <ACRONYM
CLASS="ACRONYM"
>XID</ACRONYM
>
assigned (Andres Freund)
</P
><P
> This fixes some corner cases in which transactions on standby
servers failed to notice changes, such as new indexes.
</P
></LI
><LI
><P
> Prevent multiple processes from trying to clean a <ACRONYM
CLASS="ACRONYM"
>GIN</ACRONYM
>
index's pending list concurrently (Teodor Sigaev, Jeff Janes)
</P
><P
> This had been intentionally allowed, but it causes race conditions
that can result in vacuum missing index entries it needs to delete.
</P
></LI
></UL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN134785"
>E.18.3.2. Replication and Recovery</A
></H3
><P
></P
><UL
><LI
><P
> Allow synchronous replication to support multiple simultaneous
synchronous standby servers, not just one (Masahiko Sawada,
Beena Emerson, Michael Paquier, Fujii Masao, Kyotaro Horiguchi)
</P
><P
> The number of standby servers that must acknowledge a commit
before it is considered complete is now configurable as part of
the <A
HREF="runtime-config-replication.html#GUC-SYNCHRONOUS-STANDBY-NAMES"
>synchronous_standby_names</A
> parameter.
</P
></LI
><LI
><P
> Add new setting <TT
CLASS="LITERAL"
>remote_apply</TT
> for configuration
parameter <A
HREF="runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT"
>synchronous_commit</A
> (Thomas Munro)
</P
><P
> In this mode, the master waits for the transaction to be
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>applied</I
></SPAN
> on the standby server, not just written
to disk. That means that you can count on a transaction started
on the standby to see all commits previously acknowledged by
the master.
</P
></LI
><LI
><P
> Add a feature to the replication
protocol, and a corresponding option to <A
HREF="functions-admin.html#FUNCTIONS-REPLICATION-TABLE"
><CODE
CLASS="FUNCTION"
>pg_create_physical_replication_slot()</CODE
></A
>,
to allow reserving <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> immediately when creating a
replication slot (Gurjeet Singh, Michael Paquier)
</P
><P
> This allows the creation of a replication slot to guarantee
that all the <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> needed for a base backup will be
available.
</P
></LI
><LI
><P
> Add a <TT
CLASS="OPTION"
>--slot</TT
> option to
<A
HREF="app-pgbasebackup.html"
><SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
></A
>
(Peter Eisentraut)
</P
><P
> This lets <SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
> use a replication
slot defined for <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> streaming. After the base
backup completes, selecting the same slot for regular streaming
replication allows seamless startup of the new standby server.
</P
></LI
><LI
><P
> Extend <A
HREF="functions-admin.html#FUNCTIONS-ADMIN-BACKUP-TABLE"
><CODE
CLASS="FUNCTION"
>pg_start_backup()</CODE
></A
>
and <CODE
CLASS="FUNCTION"
>pg_stop_backup()</CODE
> to support non-exclusive backups
(Magnus Hagander)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN134818"
>E.18.3.3. Queries</A
></H3
><P
></P
><UL
><LI
><P
> Allow functions that return sets of tuples to return simple
<TT
CLASS="LITERAL"
>NULL</TT
>s (Andrew Gierth, Tom Lane)
</P
><P
> In the context of <TT
CLASS="LITERAL"
>SELECT FROM function(...)</TT
>, a function
that returned a set of composite values was previously not allowed
to return a plain <TT
CLASS="LITERAL"
>NULL</TT
> value as part of the set.
Now that is allowed and interpreted as a row of <TT
CLASS="LITERAL"
>NULL</TT
>s.
This avoids corner-case errors with, for example, unnesting an
array of composite values.
</P
></LI
><LI
><P
> Fully support array subscripts and field selections in the
target column list of an <TT
CLASS="COMMAND"
>INSERT</TT
> with multiple
<TT
CLASS="LITERAL"
>VALUES</TT
> rows (Tom Lane)
</P
><P
> Previously, such cases failed if the same target column was
mentioned more than once, e.g., <TT
CLASS="LITERAL"
>INSERT INTO tab (x[1],
x[2]) VALUES (...)</TT
>.
</P
></LI
><LI
><P
> When appropriate, postpone evaluation of <TT
CLASS="COMMAND"
>SELECT</TT
>
output expressions until after an <TT
CLASS="LITERAL"
>ORDER BY</TT
> sort
(Konstantin Knizhnik)
</P
><P
> This change ensures that volatile or expensive functions in the
output list are executed in the order suggested by <TT
CLASS="LITERAL"
>ORDER
BY</TT
>, and that they are not evaluated more times than required
when there is a <TT
CLASS="LITERAL"
>LIMIT</TT
> clause. Previously, these
properties held if the ordering was performed by an index scan or
pre-merge-join sort, but not if it was performed by a top-level
sort.
</P
></LI
><LI
><P
> Widen counters recording the number of tuples processed to 64 bits
(Andreas Scherbaum)
</P
><P
> This change allows command tags, e.g. <TT
CLASS="COMMAND"
>SELECT</TT
>, to
correctly report tuple counts larger than 4 billion. This also
applies to PL/pgSQL's <TT
CLASS="COMMAND"
>GET DIAGNOSTICS ... ROW_COUNT</TT
>
command.
</P
></LI
><LI
><P
> Avoid doing encoding conversions by converting through the
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
> encoding (Tom Lane)
</P
><P
> Previously, many conversions for Cyrillic and Central
European single-byte encodings were done by converting to a
related <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
> coding scheme and then to the
destination encoding. Aside from being inefficient, this meant
that when the conversion encountered an untranslatable character,
the error message would confusingly complain about failure to
convert to or from <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>, rather than the
user-visible encoding.
</P
></LI
><LI
><P
> Consider performing joins of foreign tables remotely only when the
tables will be accessed under the same role ID (Shigeru Hanada,
Ashutosh Bapat, Etsuro Fujita)
</P
><P
> Previously, the foreign join pushdown infrastructure left the
question of security entirely up to individual foreign data
wrappers, but that made it too easy for an <ACRONYM
CLASS="ACRONYM"
>FDW</ACRONYM
> to
inadvertently create subtle security holes. So, make it the core
code's job to determine which role ID will access each table,
and do not attempt join pushdown unless the role is the same for
all relevant relations.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN134856"
>E.18.3.4. Utility Commands</A
></H3
><P
></P
><UL
><LI
><P
> Allow <TT
CLASS="COMMAND"
>COPY</TT
> to copy the output of an
<TT
CLASS="LITERAL"
>INSERT</TT
>/<TT
CLASS="LITERAL"
>UPDATE</TT
>/<TT
CLASS="LITERAL"
>DELETE</TT
>
... <TT
CLASS="LITERAL"
>RETURNING</TT
> query (Marko Tiikkaja)
</P
><P
> Previously, an intermediate <ACRONYM
CLASS="ACRONYM"
>CTE</ACRONYM
> had to be written to
get this result.
</P
></LI
><LI
><P
> Introduce <TT
CLASS="COMMAND"
>ALTER <TT
CLASS="REPLACEABLE"
><I
>object</I
></TT
> DEPENDS ON
EXTENSION</TT
> (Abhijit Menon-Sen)
</P
><P
> This command allows a database object to be marked as depending
on an extension, so that it will be dropped automatically if
the extension is dropped (without needing <TT
CLASS="LITERAL"
>CASCADE</TT
>).
However, the object is not part of the extension, and thus will
be dumped separately by <SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
>.
</P
></LI
><LI
><P
> Make <TT
CLASS="COMMAND"
>ALTER <TT
CLASS="REPLACEABLE"
><I
>object</I
></TT
> SET SCHEMA</TT
> do nothing
when the object is already in the requested schema, rather than
throwing an error as it historically has for most object types
(Marti Raudsepp)
</P
></LI
><LI
><P
> Add options to <TT
CLASS="COMMAND"
>ALTER OPERATOR</TT
> to allow changing
the selectivity functions associated with an existing operator
(Yury Zhuravlev)
</P
></LI
><LI
><P
> Add an <TT
CLASS="OPTION"
>IF NOT EXISTS</TT
> option to <TT
CLASS="COMMAND"
>ALTER TABLE
ADD COLUMN</TT
> (Fabrízio de Royes Mello)
</P
></LI
><LI
><P
> Reduce the lock strength needed by <TT
CLASS="COMMAND"
>ALTER TABLE</TT
>
when setting fillfactor and autovacuum-related relation options
(Fabrízio de Royes Mello, Simon Riggs)
</P
></LI
><LI
><P
> Introduce <A
HREF="sql-create-access-method.html"
><TT
CLASS="COMMAND"
>CREATE
ACCESS METHOD</TT
></A
> to allow extensions to create index access
methods (Alexander Korotkov, Petr Jelínek)
</P
></LI
><LI
><P
> Add a <TT
CLASS="LITERAL"
>CASCADE</TT
> option to <TT
CLASS="COMMAND"
>CREATE
EXTENSION</TT
> to automatically create any extensions the
requested one depends on (Petr Jelínek)
</P
></LI
><LI
><P
> Make <TT
CLASS="COMMAND"
>CREATE TABLE ... LIKE</TT
> include an <TT
CLASS="TYPE"
>OID</TT
>
column if any source table has one (Bruce Momjian)
</P
></LI
><LI
><P
> If a <TT
CLASS="LITERAL"
>CHECK</TT
> constraint is declared <TT
CLASS="LITERAL"
>NOT VALID</TT
>
in a table creation command, automatically mark it as valid
(Amit Langote, Amul Sul)
</P
><P
> This is safe because the table has no existing rows. This matches
the longstanding behavior of <TT
CLASS="LITERAL"
>FOREIGN KEY</TT
> constraints.
</P
></LI
><LI
><P
> Fix <TT
CLASS="COMMAND"
>DROP OPERATOR</TT
> to clear
<TT
CLASS="STRUCTNAME"
>pg_operator</TT
>.<TT
CLASS="STRUCTFIELD"
>oprcom</TT
> and
<TT
CLASS="STRUCTNAME"
>pg_operator</TT
>.<TT
CLASS="STRUCTFIELD"
>oprnegate</TT
> links to
the dropped operator (Roma Sokolov)
</P
><P
> Formerly such links were left as-is, which could pose a problem
in the somewhat unlikely event that the dropped operator's
<TT
CLASS="TYPE"
>OID</TT
> was reused for another operator.
</P
></LI
><LI
><P
> Do not show the same subplan twice in <TT
CLASS="COMMAND"
>EXPLAIN</TT
> output
(Tom Lane)
</P
><P
> In certain cases, typically involving SubPlan nodes in index
conditions, <TT
CLASS="COMMAND"
>EXPLAIN</TT
> would print data for the same
subplan twice.
</P
></LI
><LI
><P
> Disallow creation of indexes on system columns, except for
<TT
CLASS="TYPE"
>OID</TT
> columns (David Rowley)
</P
><P
> Such indexes were never considered supported, and would very
possibly misbehave since the system might change the system-column
fields of a tuple without updating indexes. However, previously
there were no error checks to prevent them from being created.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN134925"
>E.18.3.5. Permissions Management</A
></H3
><P
></P
><UL
><LI
><P
> Use the privilege system to manage access to sensitive functions
(Stephen Frost)
</P
><P
> Formerly, many security-sensitive functions contained hard-wired
checks that would throw an error if they were called by a
non-superuser. This forced the use of superuser roles for
some relatively pedestrian tasks. The hard-wired error checks
are now gone in favor of making <SPAN
CLASS="APPLICATION"
>initdb</SPAN
> revoke the
default public <TT
CLASS="LITERAL"
>EXECUTE</TT
> privilege on these functions.
This allows installations to choose to grant usage of such
functions to trusted roles that do not need all superuser
privileges.
</P
></LI
><LI
><P
> Create some <A
HREF="default-roles.html"
>built-in roles</A
>
that can be used to grant access to what were previously
superuser-only functions (Stephen Frost)
</P
><P
> Currently the only such role is <TT
CLASS="LITERAL"
>pg_signal_backend</TT
>,
but more are expected to be added in future.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN134938"
>E.18.3.6. Data Types</A
></H3
><P
></P
><UL
><LI
><P
> Improve <A
HREF="textsearch.html"
>full-text search</A
> to support
searching for phrases, that is, lexemes appearing adjacent to each
other in a specific order, or with a specified distance between
them (Teodor Sigaev, Oleg Bartunov, Dmitry Ivanov)
</P
><P
> A phrase-search query can be specified in <TT
CLASS="TYPE"
>tsquery</TT
>
input using the new operators <TT
CLASS="LITERAL"
><-></TT
> and
<TT
CLASS="LITERAL"
><<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
>></TT
>. The former means
that the lexemes before and after it must appear adjacent to
each other in that order. The latter means they must be exactly
<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
> lexemes apart.
</P
></LI
><LI
><P
> Allow omitting one or both boundaries in an array slice specifier,
e.g. <TT
CLASS="LITERAL"
>array_col[3:]</TT
> (Yury Zhuravlev)
</P
><P
> Omitted boundaries are taken as the upper or lower limit of the
corresponding array subscript. This allows simpler specification
for many common use-cases.
</P
></LI
><LI
><P
> Be more careful about out-of-range dates and timestamps (Vitaly
Burovoy)
</P
><P
> This change prevents unexpected out-of-range errors for
<TT
CLASS="TYPE"
>timestamp with time zone</TT
> values very close to the
implementation limits. Previously, the <SPAN
CLASS="QUOTE"
>"same"</SPAN
> value might
be accepted or not depending on the <TT
CLASS="VARNAME"
>timezone</TT
> setting,
meaning that a dump and reload could fail on a value that had been
accepted when presented. Now the limits are enforced according
to the equivalent <ACRONYM
CLASS="ACRONYM"
>UTC</ACRONYM
> time, not local time, so as to
be independent of <TT
CLASS="VARNAME"
>timezone</TT
>.
</P
><P
> Also, <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> is now more careful to detect
overflow in operations that compute new date or timestamp values,
such as <TT
CLASS="TYPE"
>date</TT
> <TT
CLASS="LITERAL"
>+</TT
> <TT
CLASS="TYPE"
>integer</TT
>.
</P
></LI
><LI
><P
> For geometric data types, make sure <TT
CLASS="LITERAL"
>infinity</TT
> and
<TT
CLASS="LITERAL"
>NaN</TT
> component values are treated consistently during
input and output (Tom Lane)
</P
><P
> Such values will now always print the same as they would in
a simple <TT
CLASS="TYPE"
>float8</TT
> column, and be accepted the same way
on input. Previously the behavior was platform-dependent.
</P
></LI
><LI
><P
> Upgrade
the <A
HREF="textsearch-dictionaries.html#TEXTSEARCH-ISPELL-DICTIONARY"
><TT
CLASS="LITERAL"
>ispell</TT
></A
>
dictionary type to handle modern <SPAN
CLASS="PRODUCTNAME"
>Hunspell</SPAN
> files and
support more languages (Artur Zakirov)
</P
></LI
><LI
><P
> Implement look-behind constraints
in <A
HREF="functions-matching.html#FUNCTIONS-POSIX-REGEXP"
>regular expressions</A
>
(Tom Lane)
</P
><P
> A look-behind constraint is like a lookahead constraint in that it
consumes no text; but it checks for existence (or nonexistence)
of a match ending at the current point in the string, rather
than one starting at the current point. Similar features exist
in many other regular-expression engines.
</P
></LI
><LI
><P
> In regular expressions, if an apparent three-digit octal escape
<TT
CLASS="LITERAL"
>\</TT
><TT
CLASS="REPLACEABLE"
><I
>nnn</I
></TT
> would exceed 377 (255 decimal),
assume it is a two-digit octal escape instead (Tom Lane)
</P
><P
> This makes the behavior match current <SPAN
CLASS="APPLICATION"
>Tcl</SPAN
> releases.
</P
></LI
><LI
><P
> Add transaction ID operators <TT
CLASS="TYPE"
>xid</TT
> <TT
CLASS="LITERAL"
><></TT
>
<TT
CLASS="TYPE"
>xid</TT
> and <TT
CLASS="TYPE"
>xid</TT
> <TT
CLASS="LITERAL"
><></TT
> <TT
CLASS="TYPE"
>int4</TT
>,
for consistency with the corresponding equality operators
(Michael Paquier)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN134996"
>E.18.3.7. Functions</A
></H3
><P
></P
><UL
><LI
><P
> Add <A
HREF="functions-json.html#FUNCTIONS-JSON-PROCESSING-TABLE"
><CODE
CLASS="FUNCTION"
>jsonb_insert()</CODE
></A
>
function to insert a new element into a <TT
CLASS="TYPE"
>jsonb</TT
> array,
or a not-previously-existing key into a <TT
CLASS="TYPE"
>jsonb</TT
> object
(Dmitry Dolgov)
</P
></LI
><LI
><P
> Improve the accuracy of the <CODE
CLASS="FUNCTION"
>ln()</CODE
>, <CODE
CLASS="FUNCTION"
>log()</CODE
>,
<CODE
CLASS="FUNCTION"
>exp()</CODE
>, and <CODE
CLASS="FUNCTION"
>pow()</CODE
> functions for type
<TT
CLASS="TYPE"
>numeric</TT
> (Dean Rasheed)
</P
></LI
><LI
><P
> Add a <A
HREF="functions-math.html#FUNCTIONS-MATH-FUNC-TABLE"
><CODE
CLASS="FUNCTION"
>scale(numeric)</CODE
></A
>
function to extract the display scale of a <TT
CLASS="TYPE"
>numeric</TT
> value
(Marko Tiikkaja)
</P
></LI
><LI
><P
> Add trigonometric functions that work in degrees (Dean Rasheed)
</P
><P
> For example, <A
HREF="functions-math.html#FUNCTIONS-MATH-TRIG-TABLE"
><CODE
CLASS="FUNCTION"
>sind()</CODE
></A
>
measures its argument in degrees, whereas <CODE
CLASS="FUNCTION"
>sin()</CODE
>
measures in radians. These functions go to some lengths to
deliver exact results for values where an exact result can be
expected, for instance <TT
CLASS="LITERAL"
>sind(30) = 0.5</TT
>.
</P
></LI
><LI
><P
> Ensure that trigonometric functions handle <TT
CLASS="LITERAL"
>infinity</TT
>
and <TT
CLASS="LITERAL"
>NaN</TT
> inputs per the <ACRONYM
CLASS="ACRONYM"
>POSIX</ACRONYM
> standard
(Dean Rasheed)
</P
><P
> The <ACRONYM
CLASS="ACRONYM"
>POSIX</ACRONYM
> standard says that these functions should
return <TT
CLASS="LITERAL"
>NaN</TT
> for <TT
CLASS="LITERAL"
>NaN</TT
> input, and should throw
an error for out-of-range inputs including <TT
CLASS="LITERAL"
>infinity</TT
>.
Previously our behavior varied across platforms.
</P
></LI
><LI
><P
> Make <A
HREF="functions-datetime.html#FUNCTIONS-DATETIME-TABLE"
><CODE
CLASS="FUNCTION"
>to_timestamp(float8)</CODE
></A
>
convert float <TT
CLASS="LITERAL"
>infinity</TT
> to
timestamp <TT
CLASS="LITERAL"
>infinity</TT
> (Vitaly Burovoy)
</P
><P
> Formerly it just failed on an infinite input.
</P
></LI
><LI
><P
> Add new functions for <TT
CLASS="TYPE"
>tsvector</TT
> data (Stas Kelvich)
</P
><P
> The new functions are <A
HREF="functions-textsearch.html#TEXTSEARCH-FUNCTIONS-TABLE"
><CODE
CLASS="FUNCTION"
>ts_delete()</CODE
></A
>,
<CODE
CLASS="FUNCTION"
>ts_filter()</CODE
>, <CODE
CLASS="FUNCTION"
>unnest()</CODE
>,
<CODE
CLASS="FUNCTION"
>tsvector_to_array()</CODE
>, <CODE
CLASS="FUNCTION"
>array_to_tsvector()</CODE
>,
and a variant of <CODE
CLASS="FUNCTION"
>setweight()</CODE
> that sets the weight
only for specified lexeme(s).
</P
></LI
><LI
><P
> Allow <A
HREF="textsearch-features.html#TEXTSEARCH-STATISTICS"
><CODE
CLASS="FUNCTION"
>ts_stat()</CODE
></A
>
and <A
HREF="textsearch-features.html#TEXTSEARCH-UPDATE-TRIGGERS"
><CODE
CLASS="FUNCTION"
>tsvector_update_trigger()</CODE
></A
>
to operate on values that are of types binary-compatible with the
expected argument type, not just exactly that type; for example
allow <TT
CLASS="TYPE"
>citext</TT
> where <TT
CLASS="TYPE"
>text</TT
> is expected (Teodor
Sigaev)
</P
></LI
><LI
><P
> Add variadic functions <A
HREF="functions-comparison.html#FUNCTIONS-COMPARISON-FUNC-TABLE"
><CODE
CLASS="FUNCTION"
>num_nulls()</CODE
></A
>
and <CODE
CLASS="FUNCTION"
>num_nonnulls()</CODE
> that count the number of their
arguments that are null or non-null (Marko Tiikkaja)
</P
><P
> An example usage is <TT
CLASS="LITERAL"
>CHECK(num_nonnulls(a,b,c) = 1)</TT
>
which asserts that exactly one of a,b,c is not <TT
CLASS="LITERAL"
>NULL</TT
>.
These functions can also be used to count the number of null or
nonnull elements in an array.
</P
></LI
><LI
><P
> Add function <A
HREF="functions-string.html#FUNCTIONS-STRING-OTHER"
><CODE
CLASS="FUNCTION"
>parse_ident()</CODE
></A
>
to split a qualified, possibly quoted <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> identifier
into its parts (Pavel Stehule)
</P
></LI
><LI
><P
> In <A
HREF="functions-formatting.html#FUNCTIONS-FORMATTING-TABLE"
><CODE
CLASS="FUNCTION"
>to_number()</CODE
></A
>,
interpret a <TT
CLASS="LITERAL"
>V</TT
> format code as dividing by 10 to the
power of the number of digits following <TT
CLASS="LITERAL"
>V</TT
> (Bruce
Momjian)
</P
><P
> This makes it operate in an inverse fashion to
<CODE
CLASS="FUNCTION"
>to_char()</CODE
>.
</P
></LI
><LI
><P
> Make the <A
HREF="functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE"
><CODE
CLASS="FUNCTION"
>to_reg*()</CODE
></A
>
functions accept type <TT
CLASS="TYPE"
>text</TT
> not <TT
CLASS="TYPE"
>cstring</TT
>
(Petr Korobeinikov)
</P
><P
> This avoids the need to write an explicit cast in most cases
where the argument is not a simple literal constant.
</P
></LI
><LI
><P
> Add <A
HREF="functions-admin.html#FUNCTIONS-ADMIN-DBSIZE"
><CODE
CLASS="FUNCTION"
>pg_size_bytes()</CODE
></A
>
function to convert human-readable size strings to numbers (Pavel
Stehule, Vitaly Burovoy, Dean Rasheed)
</P
><P
> This function converts strings like those produced by
<CODE
CLASS="FUNCTION"
>pg_size_pretty()</CODE
> into bytes. An example
usage is <TT
CLASS="LITERAL"
>SELECT oid::regclass FROM pg_class WHERE
pg_total_relation_size(oid) > pg_size_bytes('10 GB')</TT
>.
</P
></LI
><LI
><P
> In <A
HREF="functions-admin.html#FUNCTIONS-ADMIN-DBSIZE"
><CODE
CLASS="FUNCTION"
>pg_size_pretty()</CODE
></A
>,
format negative numbers similarly to positive ones (Adrian
Vondendriesch)
</P
><P
> Previously, negative numbers were never abbreviated, just printed
in bytes.
</P
></LI
><LI
><P
> Add an optional <TT
CLASS="REPLACEABLE"
><I
>missing_ok</I
></TT
> argument to the <A
HREF="functions-admin.html#FUNCTIONS-ADMIN-SET-TABLE"
><CODE
CLASS="FUNCTION"
>current_setting()</CODE
></A
>
function (David Christensen)
</P
><P
> This allows avoiding an error for an unrecognized parameter
name, instead returning a <TT
CLASS="LITERAL"
>NULL</TT
>.
</P
></LI
><LI
><P
> Change various catalog-inspection functions to return
<TT
CLASS="LITERAL"
>NULL</TT
> for invalid input (Michael Paquier)
</P
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE"
><CODE
CLASS="FUNCTION"
>pg_get_viewdef()</CODE
></A
>
now returns <TT
CLASS="LITERAL"
>NULL</TT
> if given an invalid view <TT
CLASS="TYPE"
>OID</TT
>,
and several similar functions likewise return <TT
CLASS="LITERAL"
>NULL</TT
> for
bad input. Previously, such cases usually led to <SPAN
CLASS="QUOTE"
>"cache
lookup failed"</SPAN
> errors, which are not meant to occur in
user-facing cases.
</P
></LI
><LI
><P
> Fix <A
HREF="functions-admin.html#PG-REPLICATION-ORIGIN-XACT-RESET"
><CODE
CLASS="FUNCTION"
>pg_replication_origin_xact_reset()</CODE
></A
>
to not have any arguments (Fujii Masao)
</P
><P
> The documentation said that it has no arguments, and the C code did
not expect any arguments, but the entry in <TT
CLASS="STRUCTNAME"
>pg_proc</TT
>
mistakenly specified two arguments.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN135123"
>E.18.3.8. Server-Side Languages</A
></H3
><P
></P
><UL
><LI
><P
> In <A
HREF="plpgsql.html"
>PL/pgSQL</A
>, detect mismatched
<TT
CLASS="COMMAND"
>CONTINUE</TT
> and <TT
CLASS="COMMAND"
>EXIT</TT
> statements while
compiling a function, rather than at execution time
(Jim Nasby)
</P
></LI
><LI
><P
> Extend <SPAN
CLASS="APPLICATION"
>PL/Python</SPAN
>'s error-reporting and
message-reporting functions to allow specifying additional message
fields besides the primary error message (Pavel Stehule)
</P
></LI
><LI
><P
> Allow PL/Python functions to call themselves recursively
via <SPAN
CLASS="APPLICATION"
>SPI</SPAN
>, and fix the behavior when multiple
set-returning PL/Python functions are called within one query
(Alexey Grishchenko, Tom Lane)
</P
></LI
><LI
><P
> Fix session-lifespan memory leaks in PL/Python (Heikki Linnakangas,
Haribabu Kommi, Tom Lane)
</P
></LI
><LI
><P
> Modernize <SPAN
CLASS="APPLICATION"
>PL/Tcl</SPAN
> to use Tcl's <SPAN
CLASS="QUOTE"
>"object"</SPAN
>
<ACRONYM
CLASS="ACRONYM"
>API</ACRONYM
>s instead of simple strings (Jim Nasby, Karl
Lehenbauer)
</P
><P
> This can improve performance substantially in some cases.
Note that <SPAN
CLASS="APPLICATION"
>PL/Tcl</SPAN
> now requires Tcl 8.4 or later.
</P
></LI
><LI
><P
> In <SPAN
CLASS="APPLICATION"
>PL/Tcl</SPAN
>, make database-reported errors return
additional information in Tcl's <TT
CLASS="VARNAME"
>errorCode</TT
> global
variable (Jim Nasby, Tom Lane)
</P
><P
> This feature follows the Tcl convention for returning auxiliary
data about an error.
</P
></LI
><LI
><P
> Fix <SPAN
CLASS="APPLICATION"
>PL/Tcl</SPAN
> to perform encoding conversion between
the database encoding and <TT
CLASS="LITERAL"
>UTF-8</TT
>, which is what Tcl
expects (Tom Lane)
</P
><P
> Previously, strings were passed through without conversion,
leading to misbehavior with non-<TT
CLASS="LITERAL"
>ASCII</TT
> characters when
the database encoding was not <TT
CLASS="LITERAL"
>UTF-8</TT
>.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN135158"
>E.18.3.9. Client Interfaces</A
></H3
><P
></P
><UL
><LI
><P
> Add a nonlocalized version of
the <A
HREF="protocol-error-fields.html"
>severity field</A
> in
error and notice messages (Tom Lane)
</P
><P
> This change allows client code to determine severity of an error or
notice without having to worry about localized variants of the
severity strings.
</P
></LI
><LI
><P
> Introduce a feature in <SPAN
CLASS="APPLICATION"
>libpq</SPAN
> whereby the
<TT
CLASS="LITERAL"
>CONTEXT</TT
> field of messages can be suppressed, either
always or only for non-error messages (Pavel Stehule)
</P
><P
> The default behavior of <A
HREF="libpq-status.html#LIBPQ-PQERRORMESSAGE"
><CODE
CLASS="FUNCTION"
>PQerrorMessage()</CODE
></A
>
is now to print <TT
CLASS="LITERAL"
>CONTEXT</TT
>
only for errors. The new function <A
HREF="libpq-control.html#LIBPQ-PQSETERRORCONTEXTVISIBILITY"
><CODE
CLASS="FUNCTION"
>PQsetErrorContextVisibility()</CODE
></A
>
can be used to adjust this.
</P
></LI
><LI
><P
> Add support in <SPAN
CLASS="APPLICATION"
>libpq</SPAN
> for regenerating an error
message with a different verbosity level (Alex Shulgin)
</P
><P
> This is done with the new function <A
HREF="libpq-exec.html#LIBPQ-PQRESULTVERBOSEERRORMESSAGE"
><CODE
CLASS="FUNCTION"
>PQresultVerboseErrorMessage()</CODE
></A
>.
This supports <SPAN
CLASS="APPLICATION"
>psql</SPAN
>'s new <TT
CLASS="LITERAL"
>\errverbose</TT
>
feature, and may be useful for other clients as well.
</P
></LI
><LI
><P
> Improve <SPAN
CLASS="APPLICATION"
>libpq</SPAN
>'s <A
HREF="libpq-status.html#LIBPQ-PQHOST"
><CODE
CLASS="FUNCTION"
>PQhost()</CODE
></A
> function to return
useful data for default Unix-socket connections (Tom Lane)
</P
><P
> Previously it would return <TT
CLASS="LITERAL"
>NULL</TT
> if no explicit host
specification had been given; now it returns the default socket
directory path.
</P
></LI
><LI
><P
> Fix <SPAN
CLASS="APPLICATION"
>ecpg</SPAN
>'s lexer to handle line breaks within
comments starting on preprocessor directive lines (Michael Meskes)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN135193"
>E.18.3.10. Client Applications</A
></H3
><P
></P
><UL
><LI
><P
> Add a <TT
CLASS="OPTION"
>--strict-names</TT
> option
to <A
HREF="app-pgdump.html"
><SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
></A
>
and <A
HREF="app-pgrestore.html"
><SPAN
CLASS="APPLICATION"
>pg_restore</SPAN
></A
>
(Pavel Stehule)
</P
><P
> This option causes the program to complain if there is no match
for a <TT
CLASS="OPTION"
>-t</TT
> or <TT
CLASS="OPTION"
>-n</TT
> option, rather
than silently doing nothing.
</P
></LI
><LI
><P
> In <SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
>, dump locally-made changes of privilege
assignments for system objects (Stephen Frost)
</P
><P
> While it has always been possible for a superuser to change
the privilege assignments for built-in or extension-created
objects, such changes were formerly lost in a dump and reload.
Now, <SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
> recognizes and dumps such changes.
(This works only when dumping from a 9.6 or later server, however.)
</P
></LI
><LI
><P
> Allow <SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
> to dump non-extension-owned objects
that are within an extension-owned schema
(Martín Marqués)
</P
><P
> Previously such objects were ignored because they were mistakenly
assumed to belong to the extension owning their schema.
</P
></LI
><LI
><P
> In <SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
> output, include the table name in object
tags for object types that are only uniquely named per-table
(for example, triggers) (Peter Eisentraut)
</P
></LI
></UL
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN135218"
>E.18.3.10.1. <A
HREF="app-psql.html"
><SPAN
CLASS="APPLICATION"
>psql</SPAN
></A
></A
></H4
><P
></P
><UL
><LI
><P
> Support multiple <TT
CLASS="OPTION"
>-c</TT
> and <TT
CLASS="OPTION"
>-f</TT
>
command-line options (Pavel Stehule, Catalin Iacob)
</P
><P
> The specified operations are carried out in the order in which the
options are given, and then <SPAN
CLASS="APPLICATION"
>psql</SPAN
> terminates.
</P
></LI
><LI
><P
> Add a <TT
CLASS="COMMAND"
>\crosstabview</TT
> command that prints the results of
a query in a cross-tabulated display (Daniel Vérité)
</P
><P
> In the crosstab display, data values from one query result column
are placed in a grid whose column and row headers come from other
query result columns.
</P
></LI
><LI
><P
> Add an <TT
CLASS="LITERAL"
>\errverbose</TT
> command that shows the last server
error at full verbosity (Alex Shulgin)
</P
><P
> This is useful after getting an unexpected error — you
no longer need to adjust the <TT
CLASS="VARNAME"
>VERBOSITY</TT
> variable and
recreate the failure in order to see error fields that are not
shown by default.
</P
></LI
><LI
><P
> Add <TT
CLASS="LITERAL"
>\ev</TT
> and <TT
CLASS="LITERAL"
>\sv</TT
> commands for editing and
showing view definitions (Petr Korobeinikov)
</P
><P
> These are parallel to the existing <TT
CLASS="LITERAL"
>\ef</TT
> and
<TT
CLASS="LITERAL"
>\sf</TT
> commands for functions.
</P
></LI
><LI
><P
> Add a <TT
CLASS="COMMAND"
>\gexec</TT
> command that executes a query and
re-submits the result(s) as new queries (Corey Huinker)
</P
></LI
><LI
><P
> Allow <TT
CLASS="LITERAL"
>\pset C <TT
CLASS="REPLACEABLE"
><I
>string</I
></TT
></TT
>
to set the table title, for consistency with <TT
CLASS="LITERAL"
>\C
<TT
CLASS="REPLACEABLE"
><I
>string</I
></TT
></TT
> (Bruce Momjian)
</P
></LI
><LI
><P
> In <TT
CLASS="LITERAL"
>\pset expanded auto</TT
> mode, do not use expanded
format for query results with only one column (Andreas Karlsson,
Robert Haas)
</P
></LI
><LI
><P
> Improve the headers output by the <TT
CLASS="COMMAND"
>\watch</TT
> command
(Michael Paquier, Tom Lane)
</P
><P
> Include the <TT
CLASS="COMMAND"
>\pset title</TT
> string if one has
been set, and shorten the prefabricated part of the
header to be <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>timestamp</I
></TT
> (every
<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
>s)</TT
>. Also, the timestamp format now
obeys <SPAN
CLASS="APPLICATION"
>psql</SPAN
>'s locale environment.
</P
></LI
><LI
><P
> Improve tab-completion logic to consider the entire input query,
not only the current line (Tom Lane)
</P
><P
> Previously, breaking a command into multiple lines defeated any
tab completion rules that needed to see words on earlier lines.
</P
></LI
><LI
><P
> Numerous minor improvements in tab-completion behavior (Peter
Eisentraut, Vik Fearing, Kevin Grittner, Kyotaro Horiguchi, Jeff
Janes, Andreas Karlsson, Fujii Masao, Thomas Munro, Masahiko
Sawada, Pavel Stehule)
</P
></LI
><LI
><P
> Add a <TT
CLASS="LITERAL"
>PROMPT</TT
> option <TT
CLASS="LITERAL"
>%p</TT
> to insert the
process ID of the connected backend (Julien Rouhaud)
</P
></LI
><LI
><P
> Introduce a feature whereby the <TT
CLASS="LITERAL"
>CONTEXT</TT
> field of
messages can be suppressed, either always or only for non-error
messages (Pavel Stehule)
</P
><P
> Printing <TT
CLASS="LITERAL"
>CONTEXT</TT
> only for errors is now the default
behavior. This can be changed by setting the special variable
<TT
CLASS="VARNAME"
>SHOW_CONTEXT</TT
>.
</P
></LI
><LI
><P
> Make <TT
CLASS="COMMAND"
>\df+</TT
> show function access privileges and
parallel-safety attributes (Michael Paquier)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN135283"
>E.18.3.10.2. <A
HREF="pgbench.html"
><SPAN
CLASS="APPLICATION"
>pgbench</SPAN
></A
></A
></H4
><P
></P
><UL
><LI
><P
> SQL commands in <SPAN
CLASS="APPLICATION"
>pgbench</SPAN
> scripts are now ended by
semicolons, not newlines (Kyotaro Horiguchi, Tom Lane)
</P
><P
> This change allows SQL commands in scripts to span multiple lines.
Existing custom scripts will need to be modified to add a semicolon
at the end of each line that does not have one already. (Doing so
does not break the script for use with older versions
of <SPAN
CLASS="APPLICATION"
>pgbench</SPAN
>.)
</P
></LI
><LI
><P
> Support floating-point arithmetic, as well as some <A
HREF="pgbench.html#PGBENCH-BUILTIN-FUNCTIONS"
>built-in functions</A
>, in
expressions in backslash commands (Fabien Coelho)
</P
></LI
><LI
><P
> Replace <TT
CLASS="COMMAND"
>\setrandom</TT
> with built-in functions (Fabien
Coelho)
</P
><P
> The new built-in functions include <A
HREF="pgbench.html#PGBENCH-FUNCTIONS"
><CODE
CLASS="FUNCTION"
>random()</CODE
></A
>,
<CODE
CLASS="FUNCTION"
>random_exponential()</CODE
>, and
<CODE
CLASS="FUNCTION"
>random_gaussian()</CODE
>, which perform the same work as
<TT
CLASS="COMMAND"
>\setrandom</TT
>, but are easier to use since they can be
embedded in larger expressions. Since these additions have made
<TT
CLASS="COMMAND"
>\setrandom</TT
> obsolete, remove it.
</P
></LI
><LI
><P
> Allow invocation of multiple copies of the built-in scripts,
not only custom scripts (Fabien Coelho)
</P
><P
> This is done with the new <TT
CLASS="OPTION"
>-b</TT
> switch, which works
similarly to <TT
CLASS="OPTION"
>-f</TT
> for custom scripts.
</P
></LI
><LI
><P
> Allow changing the selection probabilities (weights) for scripts
(Fabien Coelho)
</P
><P
> When multiple scripts are specified, each <SPAN
CLASS="APPLICATION"
>pgbench</SPAN
>
transaction randomly chooses one to execute. Formerly this was
always done with uniform probability, but now different selection
probabilities can be specified for different scripts.
</P
></LI
><LI
><P
> Collect statistics for each script in a multi-script run (Fabien
Coelho)
</P
><P
> This feature adds an intermediate level of detail to existing
global and per-command statistics printouts.
</P
></LI
><LI
><P
> Add a <TT
CLASS="OPTION"
>--progress-timestamp</TT
> option to report progress
with Unix epoch timestamps, instead of time since the run started
(Fabien Coelho)
</P
></LI
><LI
><P
> Allow the number of client connections (<TT
CLASS="OPTION"
>-c</TT
>) to not
be an exact multiple of the number of threads (<TT
CLASS="OPTION"
>-j</TT
>)
(Fabien Coelho)
</P
></LI
><LI
><P
> When the <TT
CLASS="OPTION"
>-T</TT
> option is used, stop promptly at the end
of the specified time (Fabien Coelho)
</P
><P
> Previously, specifying a low transaction rate could cause
<SPAN
CLASS="APPLICATION"
>pgbench</SPAN
> to wait significantly longer than
specified.
</P
></LI
></UL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN135329"
>E.18.3.11. Server Applications</A
></H3
><P
></P
><UL
><LI
><P
> Improve error reporting during <SPAN
CLASS="APPLICATION"
>initdb</SPAN
>'s
post-bootstrap phase (Tom Lane)
</P
><P
> Previously, an error here led to reporting the entire input
file as the <SPAN
CLASS="QUOTE"
>"failing query"</SPAN
>; now just the current
query is reported. To get the desired behavior, queries in
<SPAN
CLASS="APPLICATION"
>initdb</SPAN
>'s input files must be separated by blank
lines.
</P
></LI
><LI
><P
> Speed up <SPAN
CLASS="APPLICATION"
>initdb</SPAN
> by using just one
standalone-backend session for all the post-bootstrap steps
(Tom Lane)
</P
></LI
><LI
><P
> Improve <A
HREF="app-pgrewind.html"
><SPAN
CLASS="APPLICATION"
>pg_rewind</SPAN
></A
>
so that it can work when the target timeline changes (Alexander
Korotkov)
</P
><P
> This allows, for example, rewinding a promoted standby back to
some state of the old master's timeline.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN135346"
>E.18.3.12. Source Code</A
></H3
><P
></P
><UL
><LI
><P
> Remove obsolete
<CODE
CLASS="FUNCTION"
>heap_formtuple</CODE
>/<CODE
CLASS="FUNCTION"
>heap_modifytuple</CODE
>/<CODE
CLASS="FUNCTION"
>heap_deformtuple</CODE
>
functions (Peter Geoghegan)
</P
></LI
><LI
><P
> Add macros to make <CODE
CLASS="FUNCTION"
>AllocSetContextCreate()</CODE
> calls simpler
and safer (Tom Lane)
</P
><P
> Writing out the individual sizing parameters for a memory context
is now deprecated in favor of using one of the new
macros <TT
CLASS="SYMBOL"
>ALLOCSET_DEFAULT_SIZES</TT
>,
<TT
CLASS="SYMBOL"
>ALLOCSET_SMALL_SIZES</TT
>,
or <TT
CLASS="SYMBOL"
>ALLOCSET_START_SMALL_SIZES</TT
>.
Existing code continues to work, however.
</P
></LI
><LI
><P
> Unconditionally use <TT
CLASS="LITERAL"
>static inline</TT
> functions in header
files (Andres Freund)
</P
><P
> This may result in warnings and/or wasted code space with very
old compilers, but the notational improvement seems worth it.
</P
></LI
><LI
><P
> Improve <SPAN
CLASS="APPLICATION"
>TAP</SPAN
> testing infrastructure (Michael
Paquier, Craig Ringer, Álvaro Herrera, Stephen Frost)
</P
><P
> Notably, it is now possible to test recovery scenarios using
this infrastructure.
</P
></LI
><LI
><P
> Make <TT
CLASS="VARNAME"
>trace_lwlocks</TT
> identify individual locks by name
(Robert Haas)
</P
></LI
><LI
><P
> Improve <SPAN
CLASS="APPLICATION"
>psql</SPAN
>'s tab-completion code infrastructure
(Thomas Munro, Michael Paquier)
</P
><P
> Tab-completion rules are now considerably easier to write, and
more compact.
</P
></LI
><LI
><P
> Nail the <TT
CLASS="STRUCTNAME"
>pg_shseclabel</TT
> system catalog into cache,
so that it is available for access during connection authentication
(Adam Brightwell)
</P
><P
> The core code does not use this catalog for authentication,
but extensions might wish to consult it.
</P
></LI
><LI
><P
> Restructure <A
HREF="indexam.html"
>index access
method <ACRONYM
CLASS="ACRONYM"
>API</ACRONYM
></A
> to hide most of it at
the <SPAN
CLASS="APPLICATION"
>C</SPAN
> level (Alexander Korotkov, Andrew Gierth)
</P
><P
> This change modernizes the index <ACRONYM
CLASS="ACRONYM"
>AM API</ACRONYM
> to look more
like the designs we have adopted for foreign data wrappers and
tablesample handlers. This simplifies the <SPAN
CLASS="APPLICATION"
>C</SPAN
> code
and makes it much more practical to define index access methods in
installable extensions. A consequence is that most of the columns
of the <TT
CLASS="STRUCTNAME"
>pg_am</TT
> system catalog have disappeared.
New <A
HREF="functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE"
>inspection
functions</A
> have been added to allow SQL queries to determine
index AM properties that used to be discoverable
from <TT
CLASS="STRUCTNAME"
>pg_am</TT
>.
</P
></LI
><LI
><P
> Add <A
HREF="catalog-pg-init-privs.html"
><TT
CLASS="STRUCTNAME"
>pg_init_privs</TT
></A
>
system catalog to hold original privileges
of <SPAN
CLASS="APPLICATION"
>initdb</SPAN
>-created and extension-created objects
(Stephen Frost)
</P
><P
> This infrastructure allows <SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
> to dump changes
that an installation may have made in privileges attached to
system objects. Formerly, such changes would be lost in a dump
and reload, but now they are preserved.
</P
></LI
><LI
><P
> Change the way that extensions allocate custom <TT
CLASS="LITERAL"
>LWLocks</TT
>
(Amit Kapila, Robert Haas)
</P
><P
> The <CODE
CLASS="FUNCTION"
>RequestAddinLWLocks()</CODE
> function is removed,
and replaced by <CODE
CLASS="FUNCTION"
>RequestNamedLWLockTranche()</CODE
>.
This allows better identification of custom <TT
CLASS="LITERAL"
>LWLocks</TT
>,
and is less error-prone.
</P
></LI
><LI
><P
> Improve the isolation tester to allow multiple sessions to wait
concurrently, allowing testing of deadlock scenarios (Robert Haas)
</P
></LI
><LI
><P
> Introduce extensible node types (KaiGai Kohei)
</P
><P
> This change allows <SPAN
CLASS="APPLICATION"
>FDW</SPAN
>s or custom scan providers
to store data in a plan tree in a more convenient format than
was previously possible.
</P
></LI
><LI
><P
> Make the planner deal with post-scan/join query steps by generating
and comparing <TT
CLASS="LITERAL"
>Paths</TT
>, replacing a lot of ad-hoc logic
(Tom Lane)
</P
><P
> This change provides only marginal user-visible improvements today,
but it enables future work on a lot of upper-planner improvements
that were impractical to tackle using the old code structure.
</P
></LI
><LI
><P
> Support partial aggregation (David Rowley, Simon Riggs)
</P
><P
> This change allows the computation of an aggregate function to be
split into separate parts, for example so that parallel worker
processes can cooperate on computing an aggregate. In future
it might allow aggregation across local and remote data to occur
partially on the remote end.
</P
></LI
><LI
><P
> Add a generic command progress reporting facility (Vinayak Pokale,
Rahila Syed, Amit Langote, Robert Haas)
</P
></LI
><LI
><P
> Separate out <SPAN
CLASS="APPLICATION"
>psql</SPAN
>'s <SPAN
CLASS="APPLICATION"
>flex</SPAN
> lexer to
make it usable by other client programs (Tom Lane, Kyotaro
Horiguchi)
</P
><P
> This eliminates code duplication for programs that need to be able
to parse SQL commands well enough to identify command boundaries.
Doing that in full generality is more painful than one could
wish, and up to now only <SPAN
CLASS="APPLICATION"
>psql</SPAN
> has really gotten
it right among our supported client programs.
</P
><P
> A new source-code subdirectory <TT
CLASS="FILENAME"
>src/fe_utils/</TT
> has
been created to hold this and other code that is shared across
our client programs. Formerly such sharing was accomplished by
symbolic linking or copying source files at build time, which
was ugly and required duplicate compilation.
</P
></LI
><LI
><P
> Introduce <TT
CLASS="LITERAL"
>WaitEventSet</TT
> <ACRONYM
CLASS="ACRONYM"
>API</ACRONYM
> to allow
efficient waiting for event sets that usually do not change from
one wait to the next (Andres Freund, Amit Kapila)
</P
></LI
><LI
><P
> Add a generic interface for writing <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> records
(Alexander Korotkov, Petr Jelínek, Markus Nullmeier)
</P
><P
> This change allows extensions to write <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> records for
changes to pages using a standard layout. The problem of needing to
replay <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> without access to the extension is solved by
having generic replay code. This allows extensions to implement,
for example, index access methods and have <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
>
support for them.
</P
></LI
><LI
><P
> Support generic <ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> messages for logical decoding
(Petr Jelínek, Andres Freund)
</P
><P
> This feature allows extensions to insert data into the
<ACRONYM
CLASS="ACRONYM"
>WAL</ACRONYM
> stream that can be read by logical-decoding
plugins, but is not connected to physical data restoration.
</P
></LI
><LI
><P
> Allow SP-GiST operator classes to store an arbitrary
<SPAN
CLASS="QUOTE"
>"traversal value"</SPAN
> while descending the index (Alexander
Lebedev, Teodor Sigaev)
</P
><P
> This is somewhat like the <SPAN
CLASS="QUOTE"
>"reconstructed value"</SPAN
>, but it
could be any arbitrary chunk of data, not necessarily of the same
data type as the indexed column.
</P
></LI
><LI
><P
> Introduce a <TT
CLASS="LITERAL"
>LOG_SERVER_ONLY</TT
> message level for
<CODE
CLASS="FUNCTION"
>ereport()</CODE
> (David Steele)
</P
><P
> This level acts like <TT
CLASS="LITERAL"
>LOG</TT
> except that the message is
never sent to the client. It is meant for use in auditing and
similar applications.
</P
></LI
><LI
><P
> Provide a <TT
CLASS="FILENAME"
>Makefile</TT
> target to build all generated
headers (Michael Paquier, Tom Lane)
</P
><P
> <TT
CLASS="LITERAL"
>submake-generated-headers</TT
> can now be invoked to ensure
that generated backend header files are up-to-date. This is
useful in subdirectories that might be built <SPAN
CLASS="QUOTE"
>"standalone"</SPAN
>.
</P
></LI
><LI
><P
> Support OpenSSL 1.1.0 (Andreas Karlsson, Heikki Linnakangas)
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN135463"
>E.18.3.13. Additional Modules</A
></H3
><P
></P
><UL
><LI
><P
> Add configuration parameter <TT
CLASS="LITERAL"
>auto_explain.sample_rate</TT
> to
allow <A
HREF="auto-explain.html"
><TT
CLASS="FILENAME"
>contrib/auto_explain</TT
></A
>
to capture just a configurable fraction of all queries (Craig
Ringer, Julien Rouhaud)
</P
><P
> This allows reduction of overhead for heavy query traffic, while
still getting useful information on average.
</P
></LI
><LI
><P
> Add <A
HREF="bloom.html"
><TT
CLASS="FILENAME"
>contrib/bloom</TT
></A
> module that
implements an index access method based on Bloom filtering (Teodor
Sigaev, Alexander Korotkov)
</P
><P
> This is primarily a proof-of-concept for non-core index access
methods, but it could be useful in its own right for queries that
search many columns.
</P
></LI
><LI
><P
> In <A
HREF="cube.html"
><TT
CLASS="FILENAME"
>contrib/cube</TT
></A
>, introduce
distance operators for cubes, and support kNN-style searches in
GiST indexes on cube columns (Stas Kelvich)
</P
></LI
><LI
><P
> Make <TT
CLASS="FILENAME"
>contrib/hstore</TT
>'s <A
HREF="hstore.html#HSTORE-FUNC-TABLE"
><CODE
CLASS="FUNCTION"
>hstore_to_jsonb_loose()</CODE
></A
>
and <CODE
CLASS="FUNCTION"
>hstore_to_json_loose()</CODE
> functions agree on what
is a number (Tom Lane)
</P
><P
> Previously, <CODE
CLASS="FUNCTION"
>hstore_to_jsonb_loose()</CODE
> would convert
numeric-looking strings to <ACRONYM
CLASS="ACRONYM"
>JSON</ACRONYM
> numbers, rather than
strings, even if they did not exactly match the <ACRONYM
CLASS="ACRONYM"
>JSON</ACRONYM
>
syntax specification for numbers. This was inconsistent with
<CODE
CLASS="FUNCTION"
>hstore_to_json_loose()</CODE
>, so tighten the test to match
the <ACRONYM
CLASS="ACRONYM"
>JSON</ACRONYM
> syntax.
</P
></LI
><LI
><P
> Add selectivity estimation functions for
<A
HREF="intarray.html"
><TT
CLASS="FILENAME"
>contrib/intarray</TT
></A
> operators
to improve plans for queries using those operators (Yury Zhuravlev,
Alexander Korotkov)
</P
></LI
><LI
><P
> Make <A
HREF="pageinspect.html"
><TT
CLASS="FILENAME"
>contrib/pageinspect</TT
></A
>'s
<CODE
CLASS="FUNCTION"
>heap_page_items()</CODE
> function show the raw data in each
tuple, and add new functions <CODE
CLASS="FUNCTION"
>tuple_data_split()</CODE
> and
<CODE
CLASS="FUNCTION"
>heap_page_item_attrs()</CODE
> for inspection of individual
tuple fields (Nikolay Shaplov)
</P
></LI
><LI
><P
> Add an optional <TT
CLASS="LITERAL"
>S2K</TT
> iteration count parameter to
<A
HREF="pgcrypto.html"
><TT
CLASS="FILENAME"
>contrib/pgcrypto</TT
></A
>'s
<CODE
CLASS="FUNCTION"
>pgp_sym_encrypt()</CODE
> function (Jeff Janes)
</P
></LI
><LI
><P
> Add support for <SPAN
CLASS="QUOTE"
>"word similarity"</SPAN
> to
<A
HREF="pgtrgm.html"
><TT
CLASS="FILENAME"
>contrib/pg_trgm</TT
></A
>
(Alexander Korotkov, Artur Zakirov)
</P
><P
> These functions and operators measure the similarity between one
string and the most similar single word of another string.
</P
></LI
><LI
><P
> Add configuration parameter
<TT
CLASS="VARNAME"
>pg_trgm.similarity_threshold</TT
> for
<TT
CLASS="FILENAME"
>contrib/pg_trgm</TT
>'s similarity threshold (Artur Zakirov)
</P
><P
> This threshold has always been configurable, but formerly it was
controlled by special-purpose functions <CODE
CLASS="FUNCTION"
>set_limit()</CODE
>
and <CODE
CLASS="FUNCTION"
>show_limit()</CODE
>. Those are now deprecated.
</P
></LI
><LI
><P
> Improve <TT
CLASS="FILENAME"
>contrib/pg_trgm</TT
>'s GIN operator class to
speed up index searches in which both common and rare keys appear
(Jeff Janes)
</P
></LI
><LI
><P
> Improve performance of similarity searches in
<TT
CLASS="FILENAME"
>contrib/pg_trgm</TT
> GIN indexes (Christophe Fornaroli)
</P
></LI
><LI
><P
> Add <A
HREF="pgvisibility.html"
><TT
CLASS="FILENAME"
>contrib/pg_visibility</TT
></A
> module
to allow examining table visibility maps (Robert Haas)
</P
></LI
><LI
><P
> Add <A
HREF="sslinfo.html"
><CODE
CLASS="FUNCTION"
>ssl_extension_info()</CODE
></A
>
function to <TT
CLASS="FILENAME"
>contrib/sslinfo</TT
>, to print information
about <ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
> extensions present in the <TT
CLASS="LITERAL"
>X509</TT
>
certificate used for the current connection (Dmitry Voronin)
</P
></LI
></UL
><DIV
CLASS="SECT4"
><H4
CLASS="SECT4"
><A
NAME="AEN135540"
>E.18.3.13.1. <A
HREF="postgres-fdw.html"
><TT
CLASS="FILENAME"
>postgres_fdw</TT
></A
></A
></H4
><P
></P
><UL
><LI
><P
> Allow extension-provided operators and functions to be sent for
remote execution, if the extension is whitelisted in the foreign
server's options (Paul Ramsey)
</P
><P
> Users can enable this feature when the extension is known to exist
in a compatible version in the remote database. It allows more
efficient execution of queries involving extension operators.
</P
></LI
><LI
><P
> Consider performing sorts on the remote server (Ashutosh Bapat)
</P
></LI
><LI
><P
> Consider performing joins on the remote server (Shigeru Hanada,
Ashutosh Bapat)
</P
></LI
><LI
><P
> When feasible, perform <TT
CLASS="COMMAND"
>UPDATE</TT
> or <TT
CLASS="COMMAND"
>DELETE</TT
>
entirely on the remote server (Etsuro Fujita)
</P
><P
> Formerly, remote updates involved sending a <TT
CLASS="COMMAND"
>SELECT FOR UPDATE</TT
>
command and then updating or deleting the selected rows one-by-one.
While that is still necessary if the operation requires any local
processing, it can now be done remotely if all elements of the
query are safe to send to the remote server.
</P
></LI
><LI
><P
> Allow the fetch size to be set as a server or table option
(Corey Huinker)
</P
><P
> Formerly, <TT
CLASS="FILENAME"
>postgres_fdw</TT
> always fetched 100 rows at
a time from remote queries; now that behavior is configurable.
</P
></LI
><LI
><P
> Use a single foreign-server connection for local user IDs that
all map to the same remote user (Ashutosh Bapat)
</P
></LI
><LI
><P
> Transmit query cancellation requests to the remote server
(Michael Paquier, Etsuro Fujita)
</P
><P
> Previously, a local query cancellation request did not cause an
already-sent remote query to terminate early.
</P
></LI
></UL
></DIV
></DIV
></DIV
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