particular operator family is applicable to a particular indexable column

data type. The set of operators from the family that are actually usable

with the indexed column are whichever ones accept the column's data type

as theirlefthand input.

as theirleft-hand input.

</para>

<para>

The function has no side effects. No information about the

arguments is conveyed except via the return value. Any function

that might throw an error depending on the values of its arguments

is notleakproof.

is notleak-proof.

</entry>

</row>

<note>

<para>

Some users have reported encountering a segmentation fault using

openjade 1.4devel to build the PDFs, with a message like:

OpenJade 1.4devel to build the PDFs, with a message like:

<screen>

openjade:./stylesheet.dsl:664:2:E: flow object not accepted by port; only display flow objects accepted

make: *** [postgres-A4.tex-pdf] Segmentation fault

</screen>

Downgrading toopenjade 1.3 should get rid of this error.

Downgrading toOpenJade 1.3 should get rid of this error.

</para>

</note>

<para>

In general, the input string can contain any combination of an allowed

date specification, a whitespace character and an allowed time

specification. Note thattimezones are not supported by ECPG. It can

specification. Note thattime zones are not supported by ECPG. It can

parse them but does not apply any calculation as the

<productname>PostgreSQL</> server does for example. Timezone

specifiers are silently discarded.

int rsetnull(int t, char *ptr);

</synopsis>

The function receives an integer that indicates the type of the

variable and a pointer to the variable itself that iscasted to a C

variable and a pointer to the variable itself that iscast to a C

char* pointer.

</para>

<para>

</synopsis>

The function receives the type of the variable to test (<literal>t</>)

as well a pointer to this variable (<literal>ptr</>). Note that the

latter needs to becasted to a char*. See the function <xref

latter needs to becast to a char*. See the function <xref

linkend="rsetnull"> for a list of possible variable types.

</para>

<para>

related functions to add fields to the <command>EXPLAIN</> output.

The flag fields in <literal>es</> can be used to determine what to

print, and the state of the <structname>ForeignScanState</> node

can be inspected to provideruntime statistics in the <command>EXPLAIN

can be inspected to providerun-time statistics in the <command>EXPLAIN

ANALYZE</> case.

</para>

The <structfield>fdw_private</> list has no other restrictions and is

not interpreted by the core backend in any way. The

<structfield>fdw_exprs</> list, if not NIL, is expected to contain

expression trees that are intended to be executed atruntime. These

expression trees that are intended to be executed atrun time. These

trees will undergo post-processing by the planner to make them fully

executable.

</para>

<para>

In <function>GetForeignPlan</>, generally the passed-intargetlist can

In <function>GetForeignPlan</>, generally the passed-intarget list can

be copied into the plan node as-is. The passed scan_clauses list

contains the same clauses as <literal>baserel-&gt;baserestrictinfo</>,

but may be re-ordered for better execution efficiency. In simple cases

the FDW can just strip <structname>RestrictInfo</> nodes from the

scan_clauses list (using <function>extract_actual_clauses</>) and put

all the clauses into the plan node's qual list, which means that all the

clauses will be checked by the executor atruntime. More complex FDWs

clauses will be checked by the executor atrun time. More complex FDWs

may be able to check some of the clauses internally, in which case those

clauses can be removed from the plan node's qual list so that the

executor doesn't waste time rechecking them.

to ensure that it gets massaged into executable form. It would probably

also put control information into the plan node's

<structfield>fdw_private</> field to tell the execution functions what

to do atruntime. The query transmitted to the remote server would

to do atrun time. The query transmitted to the remote server would

involve something like <literal>WHERE <replaceable>foreign_variable</> =

$1</literal>, with the parameter value obtained atruntime from

$1</literal>, with the parameter value obtained atrun time from

evaluation of the <structfield>fdw_exprs</> expression tree.

</para>

<literal>required_outer</> and list the specific join clause(s) in

<literal>param_clauses</>. In <function>GetForeignPlan</>, the

<replaceable>local_variable</> portion of the join clause would be added

to <structfield>fdw_exprs</>, and then atruntime the case works the

to <structfield>fdw_exprs</>, and then atrun time the case works the

same as for an ordinary restriction clause.

</para>

<listitem>

<para>

This is aboolean option. If true, it specifies that values of the

This is aBoolean option. If true, it specifies that values of the

column should not be matched against the null string (that is, the

file-level <literal>null</literal> option). This has the same effect

as listing the column in <command>COPY</>'s

<para>

Now you are ready to create the foreign data table. Using the

<command>CREATE FOREIGN TABLE</> command, you will need to define

the columns for the table, the CSVfilename, and its format:

the columns for the table, the CSVfile name, and its format:

<programlisting>

CREATE FOREIGN TABLE pglog (

<literal>array_to_json(anyarray [, pretty_bool])</literal>

</entry>

<entry>

Returns the array as JSON. APostgres multi-dimensional array

Returns the array as JSON. APostgreSQL multidimensional array

becomes a JSON array of arrays. Line feeds will be added between

dimension 1 elements if pretty_bool is true.

dimension 1 elements if<parameter>pretty_bool</parameter> is true.

</entry>

<entry><literal>array_to_json('{{1,5},{99,100}}'::int[])</literal></entry>

<entry><literal>[[1,5],[99,100]]</literal></entry>

</entry>

<entry>

Returns the row as JSON. Line feeds will be added between level

1 elements if pretty_bool is true.

1 elements if<parameter>pretty_bool</parameter> is true.

</entry>

<entry><literal>row_to_json(row(1,'foo'))</literal></entry>

<entry><literal>{"f1":1,"f2":"foo"}</literal></entry>

<entry><literal><function>pg_get_viewdef(<parameter>view_name</parameter>, <parameter>pretty_bool</>)</function></literal></entry>

<entry><type>text</type></entry>

<entry>get underlying <command>SELECT</command> command for view,

lines with fields are wrapped to 80 columns if pretty_bool is true (<emphasis>deprecated</emphasis>)</entry>

lines with fields are wrapped to 80 columns if<parameter>pretty_bool</parameter> is true (<emphasis>deprecated</emphasis>)</entry>

</row>

<row>

<entry><literal><function>pg_get_viewdef(<parameter>view_oid</parameter>)</function></literal></entry>

<entry><literal><function>pg_get_viewdef(<parameter>view_oid</parameter>, <parameter>pretty_bool</>)</function></literal></entry>

<entry><type>text</type></entry>

<entry>get underlying <command>SELECT</command> command for view,

lines with fields are wrapped to 80 columns if pretty_bool is true</entry>

lines with fields are wrapped to 80 columns if<parameter>pretty_bool</parameter> is true</entry>

</row>

<row>

<entry><literal><function>pg_get_viewdef(<parameter>view_oid</parameter>, <parameter>wrap_int</>)</function></literal></entry>

<row>

<entry><literal><function>pg_tablespace_location(<parameter>tablespace_oid</parameter>)</function></literal></entry>

<entry><type>text</type></entry>

<entry>get the path in thefilesystem that this tablespace is located in</entry>

<entry>get the path in thefile system that this tablespace is located in</entry>

</row>

<row>

<entry><literal><function>pg_typeof(<parameter>any</parameter>)</function></literal></entry>

If any of the keys can be null, also palloc an array of

<literal>*nkeys</> booleans, store its address at

<literal>*nullFlags</>, and set these null flags as needed.

<literal>*nullFlags</> can be left NULL (its initial value)

<literal>*nullFlags</> can be left<symbol>NULL</symbol> (its initial value)

if all keys are non-null.

The return value can be NULL if the item contains no keys.

The return value can be<symbol>NULL</symbol> if the item contains no keys.

</para>

</listitem>

</varlistentry>

</para>

<para>

Multi-column <acronym>GIN</acronym> indexes are implemented by building

Multicolumn <acronym>GIN</acronym> indexes are implemented by building

a single B-tree over composite values (column number, key value). The

key values for different columns can be of different types.

</para>

a lot of random I/O. Beginning in version 9.2, PostgreSQL supports a more

efficient method to build GiST indexes based on buffering, which can

dramatically reduce the number of random I/Os needed for non-ordered data

sets. For well-ordereddatasets the benefit is smaller or non-existent,

sets. For well-ordereddata sets the benefit is smaller or non-existent,

because only a small number of pages receive new tuples at a time, and

those pages fit in cache even if the index as whole does not.

</para>

ScanKey orderbys,

int norderbys);

</programlisting>

Start or restart anindexscan, possibly with new scan keys. (To restart

Start or restart anindex scan, possibly with new scan keys. (To restart

using previously-passed keys, NULL is passed for <literal>keys</> and/or

<literal>orderbys</>.) Note that it is not allowed for

the number of keys or order-by operators to be larger than

</para>

<para>

The host part may be eitherhostname or an IP address. To specify an

The host part may be eitherhost name or an IP address. To specify an

IPv6 host address, enclose it in square brackets:

<synopsis>

postgresql://[2001:db8::1234]/database