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Add documentation for opclass options

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911e7020770 added opclass options and adjusted documentation for each
particular affected opclass.  However, documentation for extendability was
not adjusted.  This commit adjusts documentation for interfaces of index AMs
and opclasses.

Discussion: https://postgr.es/m/CAH2-WzmQnW6%2Bz5F9AW%2BSz%2BzEcEvXofTwh_A9J3%3D_WA-FBP0wYg%40mail.gmail.com
Author: Alexander Korotkov
Reported-by: Peter Geoghegan
Reviewed-by: Peter Geoghegan
This commit is contained in:
Alexander Korotkov 2020-06-20 13:34:54 +03:00
parent d28ab91e71
commit 15cb2bd270
7 changed files with 336 additions and 4 deletions
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30
doc/src/sgml/brin.sgml
View File

@ -562,6 +562,36 @@ typedef struct BrinOpcInfo
</varlistentry>
</variablelist>
Optionally, an operator class for <acronym>BRIN</acronym> can supply the
following method:
<variablelist>
<varlistentry>
<term><function>void options(local_relopts *relopts)</function></term>
<listitem>
<para>
Defines set of user-visible parameters that control operator class
behavior.
</para>
<para>
The <function>options</function> function has given pointer to
<replaceable>local_relopts</replaceable> struct, which needs to be
filled with a set of operator class specific options. The options
can be accessed from other support functions using
<literal>PG_HAS_OPCLASS_OPTIONS()</literal> and
<literal>PG_GET_OPCLASS_OPTIONS()</literal> macros.
</para>
<para>
Since both key extraction for indexed value and representation of the
key in <acronym>GIN</acronym> are flexible, it may depends on
user-specified parameters.
</para>
</listitem>
</varlistentry>
</variablelist>
The core distribution includes support for two types of operator classes:
minmax and inclusion. Operator class definitions using them are shipped for
in-core data types as appropriate. Additional operator classes can be

33
doc/src/sgml/btree.sgml
View File

@ -550,6 +550,39 @@ equalimage(<replaceable>opcintype</replaceable> <type>oid</type>) returns bool
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><function>options</function></term>
<listitem>
<para>
Optionally, a B-tree operator family may provide
<function>options</function> (<quote>operator class specific
options</quote>) support functions, registered under support
function number 5. These functions define set of user-visible
parameters that control operator class behavior.
</para>
<para>
An <function>options</function> support function must have the
signature
<synopsis>
options(<replaceable>relopts</replaceable> <type>local_relopts *</type>) returns void
</synopsis>
The function has given pointer to <replaceable>local_relopts</replaceable>
struct, which needs to be filled with a set of operator class
specific options. The options can be accessed from other support
functions using <literal>PG_HAS_OPCLASS_OPTIONS()</literal> and
<literal>PG_GET_OPCLASS_OPTIONS()</literal> macros.
</para>
<para>
Currently, no B-Tree operator class has <function>options</function>
support function. B-tree doesn't allow flexible representation of keys
like GiST, SP-GiST, GIN and BRIN do. So, <function>options</function>
probably doesn't have much usage in current shape of B-tree index
access method. Nevertheless, this support function was added to B-tree
for uniformity, and probably it will found its usage during further
evolution of B-tree in <productname>PostgreSQL</productname>.
</para>
</listitem>
</varlistentry>
</variablelist>
</sect1>

26
doc/src/sgml/gin.sgml
View File

@ -380,7 +380,7 @@
<para>
Optionally, an operator class for <acronym>GIN</acronym> can supply the
following method:
following methods:
<variablelist>
<varlistentry>
@ -402,6 +402,30 @@
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><function>void options(local_relopts *relopts)</function></term>
<listitem>
<para>
Defines set of user-visible parameters that control operator class
behavior.
</para>
<para>
The <function>options</function> function has given pointer to
<replaceable>local_relopts</replaceable> struct, which needs to be
filled with s set of operator class specific options. The options
can be accessed from other support functions using
<literal>PG_HAS_OPCLASS_OPTIONS()</literal> and
<literal>PG_GET_OPCLASS_OPTIONS()</literal> macros.
</para>
<para>
Since both key extraction for indexed value and representation of the
key in <acronym>GIN</acronym> are flexible, it may depends on
user-specified parameters.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>

161
doc/src/sgml/gist.sgml
View File

@ -269,7 +269,7 @@ CREATE INDEX ON my_table USING GIST (my_inet_column inet_ops);
<para>
There are five methods that an index operator class for
<acronym>GiST</acronym> must provide, and four that are optional.
<acronym>GiST</acronym> must provide, and five that are optional.
Correctness of the index is ensured
by proper implementation of the <function>same</function>, <function>consistent</function>
and <function>union</function> methods, while efficiency (size and speed) of the
@ -287,7 +287,9 @@ CREATE INDEX ON my_table USING GIST (my_inet_column inet_ops);
if the operator class wishes to support ordered scans (nearest-neighbor
searches). The optional ninth method <function>fetch</function> is needed if the
operator class wishes to support index-only scans, except when the
<function>compress</function> method is omitted.
<function>compress</function> method is omitted. The optional tenth method
<function>options</function> is needed if the operator class provides
the user-specified parameters.
</para>
<variablelist>
@ -939,6 +941,161 @@ my_fetch(PG_FUNCTION_ARGS)
</listitem>
</varlistentry>
<varlistentry>
<term><function>options</function></term>
<listitem>
<para>
Allows defintion of user-visible parameters that control operator
class behavior.
</para>
<para>
The <acronym>SQL</acronym> declaration of the function must look like this:
<programlisting>
CREATE OR REPLACE FUNCTION my_options(internal)
RETURNS void
AS 'MODULE_PATHNAME'
LANGUAGE C STRICT;
</programlisting>
</para>
<para>
The function has given pointer to <replaceable>local_relopts</replaceable>
struct, which needs to be filled with a set of operator class
specific options. The options can be accessed from other support
functions using <literal>PG_HAS_OPCLASS_OPTIONS()</literal> and
<literal>PG_GET_OPCLASS_OPTIONS()</literal> macros.
</para>
<para>
The sample implementation of my_option() and parameters usage
in the another support function are given below:
<programlisting>
typedef enum MyEnumType
{
MY_ENUM_ON,
MY_ENUM_OFF,
MY_ENUM_AUTO
} MyEnumType;
typedef struct
{
int32 vl_len_; /* varlena header (do not touch directly!) */
int int_param; /* integer parameter */
double real_param; /* real parameter */
MyEnumType enum_param; /* enum parameter */
int str_param; /* string parameter */
} MyOptionsStruct;
/* String representations for enum values */
static relopt_enum_elt_def myEnumValues[] =
{
{"on", MY_ENUM_ON},
{"off", MY_ENUM_OFF},
{"auto", MY_ENUM_AUTO},
{(const char *) NULL} /* list terminator */
};
static char *str_param_default = "default";
/*
* Sample validatior: checks that string is not longer than 8 bytes.
*/
static void
validate_my_string_relopt(const char *value)
{
if (strlen(value) > 8)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("str_param must be at most 8 bytes")));
}
/*
* Sample filler: switches characters to lower case.
*/
static Size
fill_my_string_relopt(const char *value, void *ptr)
{
char *tmp = str_tolower(value, strlen(value), DEFAULT_COLLATION_OID);
int len = strlen(tmp);
if (ptr)
strcpy((char *) ptr, tmp);
pfree(tmp);
return len + 1;
}
PG_FUNCTION_INFO_V1(my_options);
Datum
my_options(PG_FUNCTION_ARGS)
{
local_relopts *relopts = (local_relopts *) PG_GETARG_POINTER(0);
init_local_reloptions(relopts, sizeof(MyOptionsStruct));
add_local_int_reloption(relopts, "int_param", "integer parameter",
100, 0, 1000000,
offsetof(MyOptionsStruct, int_param));
add_local_real_reloption(relopts, "real_param", "real parameter",
1.0, 0.0, 1000000.0,
offsetof(MyOptionsStruct, real_param));
add_local_enum_reloption(relopts, "enum_param", "enum parameter",
myEnumValues, MY_ENUM_ON,
"Valid values are: \"on\", \"off\" and \"auto\".",
offsetof(MyOptionsStruct, enum_param));
add_local_string_reloption(relopts, "str_param", "string parameter",
str_param_default,
&amp;validate_my_string_relopt,
&amp;fill_my_string_relopt,
offsetof(MyOptionsStruct, str_param));
PG_RETURN_VOID();
}
PG_FUNCTION_INFO_V1(my_compress);
Datum
my_compress(PG_FUNCTION_ARGS)
{
int int_param = 100;
double real_param = 1.0;
MyEnumType enum_param = MY_ENUM_ON;
char *str_param = str_param_default;
/*
* Normally, when opclass contains 'options' method, then options are always
* passed to support functions. However, if you add 'options' method to
* existing opclass, previously defined indexes have no options, so the
* check is required.
*/
if (PG_HAS_OPCLASS_OPTIONS())
{
MyOptionsStruct *options = (MyOptionsStruct *) PG_GET_OPCLASS_OPTIONS();
int_param = options->int_param;
real_param = options->real_param;
enum_param = options->enum_param;
str_param = GET_STRING_RELOPTION(options, str_param);
}
/* the rest implementation of support function */
}
</programlisting>
</para>
<para>
Since the representation of the key in <acronym>GiST</acronym> is
flexible, it may depends on user-specified parameters. For instace,
the length of key signature may be such parameter. See
<literal>gtsvector_options()</literal> for example.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>

2
doc/src/sgml/indexam.sgml
View File

@ -96,6 +96,8 @@ typedef struct IndexAmRoutine
uint16 amstrategies;
/* total number of support functions that this AM uses */
uint16 amsupport;
/* opclass options support function number or 0 */
uint16 amoptsprocnum;
/* does AM support ORDER BY indexed column's value? */
bool amcanorder;
/* does AM support ORDER BY result of an operator on indexed column? */

35
doc/src/sgml/spgist.sgml
View File

@ -858,7 +858,7 @@ typedef struct spgLeafConsistentOut
</variablelist>
<para>
The optional user-defined method is:
The optional user-defined method are:
</para>
<variablelist>
@ -875,6 +875,39 @@ typedef struct spgLeafConsistentOut
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><function>options</function></term>
<listitem>
<para>
Defines set of user-visible parameters that control operator class
behavior.
</para>
<para>
The <acronym>SQL</acronym> declaration of the function must look like this:
<programlisting>
CREATE OR REPLACE FUNCTION my_options(internal)
RETURNS void
AS 'MODULE_PATHNAME'
LANGUAGE C STRICT;
</programlisting>
</para>
<para>
The function has given pointer to <replaceable>local_relopts</replaceable>
struct, which needs to be filled with a set of operator class
specific options. The options can be accessed from other support
functions using <literal>PG_HAS_OPCLASS_OPTIONS()</literal> and
<literal>PG_GET_OPCLASS_OPTIONS()</literal> macros.
</para>
<para>
Since the representation of the key in <acronym>SP-GiST</acronym> is
flexible, it may depends on user-specified parameters.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>

53
doc/src/sgml/xindex.sgml
View File

@ -409,6 +409,13 @@
<xref linkend="btree-support-funcs"/>.
</para>
<para>
Additionally, some opclasses allow user to set specific parameters, which
controls its behavior. Each builtin index access method have optional
<function>options</function> support function, which defines set of
opclass-specific parameters.
</para>
<table tocentry="1" id="xindex-btree-support-table">
<title>B-Tree Support Functions</title>
<tgroup cols="2">
@ -450,6 +457,13 @@
</entry>
<entry>4</entry>
</row>
<row>
<entry>
Defines set of options that are specific for this operator class
(optional)
</entry>
<entry>5</entry>
</row>
</tbody>
</tgroup>
</table>
@ -485,6 +499,13 @@
</entry>
<entry>2</entry>
</row>
<row>
<entry>
Defines set of options that are specific for this operator class
(optional)
</entry>
<entry>3</entry>
</row>
</tbody>
</tgroup>
</table>
@ -560,6 +581,14 @@
index-only scans (optional)</entry>
<entry>9</entry>
</row>
<row>
<entry><function>options</function></entry>
<entry>
Defines set of options that are specific for this operator class
(optional)
</entry>
<entry>10</entry>
</row>
</tbody>
</tgroup>
</table>
@ -611,6 +640,14 @@
query qualifier</entry>
<entry>5</entry>
</row>
<row>
<entry><function>options</function></entry>
<entry>
Defines set of options that are specific for this operator class
(optional)
</entry>
<entry>6</entry>
</row>
</tbody>
</tgroup>
</table>
@ -680,6 +717,14 @@
</entry>
<entry>6</entry>
</row>
<row>
<entry><function>options</function></entry>
<entry>
Defines set of options that are specific for this operator class
(optional)
</entry>
<entry>7</entry>
</row>
</tbody>
</tgroup>
</table>
@ -730,6 +775,14 @@
</entry>
<entry>4</entry>
</row>
<row>
<entry><function>options</function></entry>
<entry>
Defines set of options that are specific for this operator class
(optional)
</entry>
<entry>5</entry>
</row>
</tbody>
</tgroup>
</table>