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Add support for invoking parser callback hooks via SPI and in cached plans.
As proof of concept, modify plpgsql to use the hooks. plpgsql is still inserting $n symbols textually, but the "back end" of the parsing process now goes through the ParamRef hook instead of using a fixed parameter-type array, and then execution only fetches actually-referenced parameters, using a hook added to ParamListInfo. Although there's a lot left to be done in plpgsql, this already cures the "if (TG_OP = 'INSERT' and NEW.foo ...)" problem, as illustrated by the changed regression test.
This commit is contained in:
Tom Lane
@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/spi.sgml,v 1.65 2009/08/05 19:31:50 alvherre Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/spi.sgml,v 1.66 2009/11/04 22:26:04 tgl Exp $ -->
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<chapter id="spi">
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<title>Server Programming Interface</title>
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@ -861,7 +861,7 @@ SPIPlanPtr SPI_prepare(const char * <parameter>command</parameter>, int <paramet
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<para>
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<function>SPI_prepare</function> creates and returns an execution
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plan for the specified command but doesn't execute the command.
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plan for the specified command, but doesn't execute the command.
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This function should only be called from a connected procedure.
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</para>
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@ -990,7 +990,7 @@ SPIPlanPtr SPI_prepare_cursor(const char * <parameter>command</parameter>, int <
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of the planner's <quote>cursor options</> parameter. This is a bitmask
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having the values shown in <filename>nodes/parsenodes.h</filename>
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for the <structfield>options</> field of <structname>DeclareCursorStmt</>.
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<function>SPI_prepare</function> always takes these options as zero.
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<function>SPI_prepare</function> always takes the cursor options as zero.
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</para>
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</refsect1>
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@ -1061,6 +1061,94 @@ SPIPlanPtr SPI_prepare_cursor(const char * <parameter>command</parameter>, int <
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<!-- *********************************************** -->
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<refentry id="spi-spi-prepare-params">
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<refmeta>
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<refentrytitle>SPI_prepare_params</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>SPI_prepare_params</refname>
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<refpurpose>prepare a plan for a command, without executing it yet</refpurpose>
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</refnamediv>
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<indexterm><primary>SPI_prepare_params</primary></indexterm>
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<refsynopsisdiv>
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<synopsis>
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SPIPlanPtr SPI_prepare_params(const char * <parameter>command</parameter>,
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ParserSetupHook <parameter>parserSetup</parameter>,
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void * <parameter>parserSetupArg</parameter>,
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int <parameter>cursorOptions</parameter>)
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<function>SPI_prepare_params</function> creates and returns an execution
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plan for the specified command, but doesn't execute the command.
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This function is equivalent to <function>SPI_prepare_cursor</function>,
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with the addition that the caller can specify parser hook functions
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to control the parsing of external parameter references.
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</para>
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</refsect1>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><literal>const char * <parameter>command</parameter></literal></term>
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<listitem>
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<para>
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command string
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>ParserSetupHook <parameter>parserSetup</parameter></literal></term>
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<listitem>
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<para>
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Parser hook setup function
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>void * <parameter>parserSetupArg</parameter></literal></term>
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<listitem>
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<para>
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passthrough argument for <parameter>parserSetup</parameter>
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>int <parameter>cursorOptions</parameter></literal></term>
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<listitem>
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<para>
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integer bitmask of cursor options; zero produces default behavior
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>
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<function>SPI_prepare_params</function> has the same return conventions as
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<function>SPI_prepare</function>.
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</para>
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</refsect1>
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</refentry>
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<!-- *********************************************** -->
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<refentry id="spi-spi-getargcount">
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<refmeta>
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<refentrytitle>SPI_getargcount</refentrytitle>
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@ -1386,14 +1474,100 @@ int SPI_execute_plan(SPIPlanPtr <parameter>plan</parameter>, Datum * <parameter>
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<function>SPI_execute</function> if successful.
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</para>
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</refsect1>
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</refentry>
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<!-- *********************************************** -->
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<refentry id="spi-spi-execute-plan-with-paramlist">
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<refmeta>
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<refentrytitle>SPI_execute_plan_with_paramlist</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>SPI_execute_plan_with_paramlist</refname>
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<refpurpose>execute a plan prepared by <function>SPI_prepare</function></refpurpose>
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</refnamediv>
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<indexterm><primary>SPI_execute_plan_with_paramlist</primary></indexterm>
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<refsynopsisdiv>
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<synopsis>
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int SPI_execute_plan_with_paramlist(SPIPlanPtr <parameter>plan</parameter>,
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ParamListInfo <parameter>params</parameter>,
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bool <parameter>read_only</parameter>,
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long <parameter>count</parameter>)
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Notes</title>
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<title>Description</title>
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<para>
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If one of the objects (a table, function, etc.) referenced by the
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prepared plan is dropped during the session then the result of
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<function>SPI_execute_plan</function> for this plan will be unpredictable.
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<function>SPI_execute_plan_with_paramlist</function> executes a plan
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prepared by <function>SPI_prepare</function>.
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This function is equivalent to <function>SPI_execute_plan</function>
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except that information about the parameter values to be passed to the
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query is presented differently. The <literal>ParamListInfo</>
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representation can be convenient for passing down values that are
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already available in that format. It also supports use of dynamic
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parameter sets via hook functions specified in <literal>ParamListInfo</>.
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</para>
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</refsect1>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><literal>SPIPlanPtr <parameter>plan</parameter></literal></term>
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<listitem>
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<para>
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execution plan (returned by <function>SPI_prepare</function>)
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>ParamListInfo <parameter>params</parameter></literal></term>
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<listitem>
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<para>
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data structure containing parameter types and values; NULL if none
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>bool <parameter>read_only</parameter></literal></term>
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<listitem>
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<para>
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<literal>true</> for read-only execution
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>long <parameter>count</parameter></literal></term>
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<listitem>
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<para>
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maximum number of rows to process or return
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>
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The return value is the same as for <function>SPI_execute_plan</function>.
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</para>
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<para>
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<varname>SPI_processed</varname> and
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<varname>SPI_tuptable</varname> are set as in
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<function>SPI_execute_plan</function> if successful.
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</para>
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</refsect1>
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</refentry>
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@ -1543,7 +1717,7 @@ Portal SPI_cursor_open(const char * <parameter>name</parameter>, SPIPlanPtr <par
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</para>
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<para>
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The passed-in data will be copied into the cursor's portal, so it
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The passed-in parameter data will be copied into the cursor's portal, so it
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can be freed while the cursor still exists.
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</para>
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</refsect1>
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@ -1667,7 +1841,7 @@ Portal SPI_cursor_open_with_args(const char *<parameter>name</parameter>,
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</para>
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<para>
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The passed-in data will be copied into the cursor's portal, so it
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The passed-in parameter data will be copied into the cursor's portal, so it
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can be freed while the cursor still exists.
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</para>
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</refsect1>
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@ -1770,6 +1944,104 @@ Portal SPI_cursor_open_with_args(const char *<parameter>name</parameter>,
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<!-- *********************************************** -->
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<refentry id="spi-spi-cursor-open-with-paramlist">
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<refmeta>
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<refentrytitle>SPI_cursor_open_with_paramlist</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>SPI_cursor_open_with_paramlist</refname>
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<refpurpose>set up a cursor using parameters</refpurpose>
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</refnamediv>
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<indexterm><primary>SPI_cursor_open_with_paramlist</primary></indexterm>
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<refsynopsisdiv>
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<synopsis>
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Portal SPI_cursor_open_with_paramlist(const char *<parameter>name</parameter>,
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SPIPlanPtr <parameter>plan</parameter>,
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ParamListInfo <parameter>params</parameter>,
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bool <parameter>read_only</parameter>)
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<function>SPI_cursor_open_with_paramlist</function> sets up a cursor
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(internally, a portal) that will execute a plan prepared by
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<function>SPI_prepare</function>.
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This function is equivalent to <function>SPI_cursor_open</function>
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except that information about the parameter values to be passed to the
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query is presented differently. The <literal>ParamListInfo</>
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representation can be convenient for passing down values that are
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already available in that format. It also supports use of dynamic
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parameter sets via hook functions specified in <literal>ParamListInfo</>.
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</para>
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<para>
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The passed-in parameter data will be copied into the cursor's portal, so it
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can be freed while the cursor still exists.
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</para>
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</refsect1>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><literal>const char * <parameter>name</parameter></literal></term>
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<listitem>
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<para>
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name for portal, or <symbol>NULL</symbol> to let the system
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select a name
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SPIPlanPtr <parameter>plan</parameter></literal></term>
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<listitem>
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<para>
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execution plan (returned by <function>SPI_prepare</function>)
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>ParamListInfo <parameter>params</parameter></literal></term>
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<listitem>
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<para>
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data structure containing parameter types and values; NULL if none
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>bool <parameter>read_only</parameter></literal></term>
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<listitem>
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<para>
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<literal>true</> for read-only execution
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>
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Pointer to portal containing the cursor. Note there is no error
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return convention; any error will be reported via <function>elog</>.
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</para>
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</refsect1>
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</refentry>
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<!-- *********************************************** -->
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<refentry id="spi-spi-cursor-find">
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<refmeta>
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<refentrytitle>SPI_cursor_find</refentrytitle>
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