</para>

<para>

Deduplication works by periodically merging groups of duplicate

tuples together, forming a single posting list tuple for each

tuples together, forming a single<firstterm>posting list</firstterm> tuple for each

group. The column key value(s) only appear once in this

representation. This is followed by a sorted array of

<acronym>TID</acronym>s that point to rows in the table. This

of statistics accumulated for this statistics object by

<xref linkend="sql-analyze"/>.

A zero value indicates that no statistics should be collected.

A negative value says to use the system default statistics target.

A negative value says to use the maximum of the statistics targets of

the referenced columns, if set, or the system default statistics target.

Positive values of <structfield>stxstattarget</structfield>

determine the target number of <quote>most common values</quote>

to collect.

servers or streaming base backup clients (i.e., the maximum number of

simultaneously running WAL sender processes). The default is

<literal>10</literal>. The value <literal>0</literal> means

replication is disabled. Abrupt streaming client disconnection might

replication is disabled. Abruptdisconnection of astreaming client might

leave an orphaned connection slot behind until a timeout is reached,

so this parameter should be set slightly higher than the maximum

number of expected clients so disconnected clients can immediately

slots</link> are allowed to retain in the <filename>pg_wal</filename>

directory at checkpoint time.

If <varname>max_slot_wal_keep_size</varname> is -1 (the default),

replication slots retain unlimited amount of WAL files.If

restart_lsn of a replication slotgets behindmore than that megabytes

from thecurrent LSN, the standby using the slot may no longer be able

replication slotsmayretainanunlimited amount of WAL files.Otherwise, if

restart_lsn of a replication slotfalls behindthe current LSN by more

than thegiven size, the standby using the slot may no longer be able

to continue replication due to removal of required WAL files. You

can see the WAL availability of replication slots

in <link linkend="view-pg-replication-slots">pg_replication_slots</link>.

</term>

<listitem>

<para>

If greater than zero, each bind parameter valuereported in

non-error statement-loggingmessages is trimmed to this many bytes.

Zero disables logging bind parameterswith statements.

If greater than zero, each bind parameter valuelogged with a

non-error statement-loggingmessage is trimmed to this many bytes.

Zero disables loggingofbind parametersfor non-error statement logs.

<literal>-1</literal> (the default) allows bind parameters to be

logged in full.

If this value is specified without units, it is taken as bytes.

a regular <command>VACUUM</command> in that it visits every page that might

contain unfrozen XIDs or MXIDs, not just those that might contain dead

tuples. The default is 150 million transactions. Although users can

set this value anywhere from zero to twobillions, <command>VACUUM</command>

set this value anywhere from zero to twobillion, <command>VACUUM</command>

will silently limit the effective value to 95% of

<xref linkend="guc-autovacuum-freeze-max-age"/>, so that a

periodical manual <command>VACUUM</command> has a chance to run before an

periodic manual <command>VACUUM</command> has a chance to run before an

anti-wraparound autovacuum is launched for the table. For more

information see

<xref linkend="vacuum-for-wraparound"/>.

a regular <command>VACUUM</command> in that it visits every page that might

contain unfrozen XIDs or MXIDs, not just those that might contain dead

tuples. The default is 150 million multixacts.

Although users can set this value anywhere from zero to twobillions,

Although users can set this value anywhere from zero to twobillion,

<command>VACUUM</command> will silently limit the effective value to 95% of

<xref linkend="guc-autovacuum-multixact-freeze-max-age"/>, so that a

periodical manual <command>VACUUM</command> has a chance to run before an

periodic manual <command>VACUUM</command> has a chance to run before an

anti-wraparound is launched for the table.

For more information see <xref linkend="vacuum-for-multixact-wraparound"/>.

</para>

Before running the <command>ATTACH PARTITION</command> command, it is

recommended to create a <literal>CHECK</literal> constraint on the table to

be attached matching the desired partition constraint. That way,

the system will be able to skip the scan to validate the implicit

the system will be able to skip the scanwhich is otherwise neededto validate the implicit

partition constraint. Without the <literal>CHECK</literal> constraint,

the table will be scanned to validate the partition constraint while

holding an <literal>ACCESS EXCLUSIVE</literal> lock on that partition

<literal>'use_json_null'</literal>.

</para>

<para>

<literal>jsonb_set_lax('[{"f1":1,"f2":null},2,null,3]', '{0,f1}',null)</literal>

<literal>jsonb_set_lax('[{"f1":1,"f2":null},2,null,3]', '{0,f1}',null)</literal>

<returnvalue>[{"f1":null,"f2":null},2,null,3]</returnvalue>

</para>

<para>

<literal>jsonb_set_lax('[{"f1":99,"f2":null},2]', '{0,f3}',null, true, 'return_target')</literal>

<literal>jsonb_set_lax('[{"f1":99,"f2":null},2]', '{0,f3}',null, true, 'return_target')</literal>

<returnvalue>[{"f1": 99, "f2": null}, 2]</returnvalue>

</para></entry>

</row>

<term><literal>connect_timeout</literal></term>

<listitem>

<para>

Maximum waitfor connection, in seconds (write as a decimal integer,

Maximumtime towaitwhile connecting, in seconds (write as a decimal integer,

e.g., <literal>10</literal>). Zero, negative, or not specified means

wait indefinitely. The minimum allowed timeout is 2 seconds, therefore

a value of <literal>1</literal> is interpreted as <literal>2</literal>.

<listitem>

<para>

Replication is only supported by tables, including partitioned tables.

Attempts to replicate other types of relations such as views, materialized

Attempts to replicate other types of relations, such as views, materialized

views, or foreign tables, will result in an error.

</para>

</listitem>

<entry><literal>waiting for checkpoint to finish</literal></entry>

<entry>

The WAL sender process is currently performing

<function>pg_start_backup</function> toset up for

taking a base backup, and waiting forbackup start

<function>pg_start_backup</function> toprepare to

take a base backup, and waiting forthe start-of-backup

checkpoint to finish.

</entry>

</row>

and sent along with the backup. The manifest is a list of every

file present in the backup with the exception of any WAL files that

may be included. It also stores the size, last modification time, and

an optional checksum for each file.

optionally a checksum for each file.

A value of <literal>force-encode</literal> forces all filenames

to be hex-encoded; otherwise, this type of encoding is performed only

for files whose names are non-UTF8 octet sequences.

<term><literal>MANIFEST_CHECKSUMS</literal> <replaceable>checksum_algorithm</replaceable></term>

<listitem>

<para>

Specifies the algorithm that should be applied to each file included

Specifies thechecksumalgorithm that should be applied to each file included

in the backup manifest. Currently, the available

algorithms are <literal>NONE</literal>, <literal>CRC32C</literal>,

<literal>SHA224</literal>, <literal>SHA256</literal>,

The statistic-gathering target for this statistics object for subsequent

<xref linkend="sql-analyze"/> operations.

The target can be set in the range 0 to 10000; alternatively, set it

to -1 to revert to using the system default statistics

to -1 to revert to using the maximum of the statistics target of the

referenced columns, if set, or the system default statistics

target (<xref linkend="guc-default-statistics-target"/>).

For more information on the use of statistics by the

<productname>PostgreSQL</productname> query planner, refer to