~ubuntu-branches/ubuntu/trusty/postgresql-9.3/trusty-updates : contents of doc/src/sgml/html/spi-spi-cursor-open.html at revision 27

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><H1
><A
NAME="SPI-SPI-CURSOR-OPEN"
></A
>SPI_cursor_open</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN62770"
></A
><H2
>Name</H2
>SPI_cursor_open&nbsp;--&nbsp;set up a cursor using a statement created with <CODE
CLASS="FUNCTION"
>SPI_prepare</CODE
></DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN62776"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>Portal SPI_cursor_open(const char * <TT
CLASS="PARAMETER"
>name</TT
>, SPIPlanPtr <TT
CLASS="PARAMETER"
>plan</TT
>,
                       Datum * <TT
CLASS="PARAMETER"
>values</TT
>, const char * <TT
CLASS="PARAMETER"
>nulls</TT
>,
                       bool <TT
CLASS="PARAMETER"
>read_only</TT
>)</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN62783"
></A
><H2
>Description</H2
><P
>   <CODE
CLASS="FUNCTION"
>SPI_cursor_open</CODE
> sets up a cursor (internally,
   a portal) that will execute a statement prepared by
   <CODE
CLASS="FUNCTION"
>SPI_prepare</CODE
>.  The parameters have the same
   meanings as the corresponding parameters to
   <CODE
CLASS="FUNCTION"
>SPI_execute_plan</CODE
>.
  </P
><P
>   Using a cursor instead of executing the statement directly has two
   benefits.  First, the result rows can be retrieved a few at a time,
   avoiding memory overrun for queries that return many rows.  Second,
   a portal can outlive the current procedure (it can, in fact, live
   to the end of the current transaction).  Returning the portal name
   to the procedure's caller provides a way of returning a row set as
   result.
  </P
><P
>   The passed-in parameter data will be copied into the cursor's portal, so it
   can be freed while the cursor still exists.
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN62791"
></A
><H2
>Arguments</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>const char * <TT
CLASS="PARAMETER"
>name</TT
></TT
></DT
><DD
><P
>      name for portal, or <TT
CLASS="SYMBOL"
>NULL</TT
> to let the system
      select a name
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>SPIPlanPtr <TT
CLASS="PARAMETER"
>plan</TT
></TT
></DT
><DD
><P
>      prepared statement (returned by <CODE
CLASS="FUNCTION"
>SPI_prepare</CODE
>)
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>Datum * <TT
CLASS="PARAMETER"
>values</TT
></TT
></DT
><DD
><P
>      An array of actual parameter values.  Must have same length as the
      statement's number of arguments.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>const char * <TT
CLASS="PARAMETER"
>nulls</TT
></TT
></DT
><DD
><P
>      An array describing which parameters are null.  Must have same length as
      the statement's number of arguments.
     </P
><P
>      If <TT
CLASS="PARAMETER"
>nulls</TT
> is <TT
CLASS="SYMBOL"
>NULL</TT
> then
      <CODE
CLASS="FUNCTION"
>SPI_cursor_open</CODE
> assumes that no parameters
      are null.  Otherwise, each entry of the <TT
CLASS="PARAMETER"
>nulls</TT
>
      array should be <TT
CLASS="LITERAL"
>'&nbsp;'</TT
> if the corresponding parameter
      value is non-null, or <TT
CLASS="LITERAL"
>'n'</TT
> if the corresponding parameter
      value is null.  (In the latter case, the actual value in the
      corresponding <TT
CLASS="PARAMETER"
>values</TT
> entry doesn't matter.)  Note
      that <TT
CLASS="PARAMETER"
>nulls</TT
> is not a text string, just an array:
      it does not need a <TT
CLASS="LITERAL"
>'\0'</TT
> terminator.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>bool <TT
CLASS="PARAMETER"
>read_only</TT
></TT
></DT
><DD
><P
><TT
CLASS="LITERAL"
>true</TT
> for read-only execution</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN62837"
></A
><H2
>Return Value</H2
><P
>   Pointer to portal containing the cursor.  Note there is no error
   return convention; any error will be reported via <CODE
CLASS="FUNCTION"
>elog</CODE
>.
  </P
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