Manual Reference Pages  - SPI_cursor_open ()

NAME

SPI_cursor_open - set up a cursor using a plan created with SPI_prepare

CONTENTS

Synopsis

SYNOPSIS

Portal SPI_cursor_open(const char * name, void * plan,
                       Datum * values, const char * nulls,
                       bool read_only)

DESCRIPTION

SPI_cursor_open sets up a cursor (internally, a portal) that will execute a plan prepared by SPI_prepare. The parameters have the same meanings as the corresponding parameters to SPI_execute_plan.

Using a cursor instead of executing the plan 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.

ARGUMENTS

const char * name
  name for portal, or NULL to let the system select a name
void * plan
  execution plan (returned by SPI_prepare)
Datum * values
  An array of actual parameter values. Must have same length as the plan’s number of arguments.
const char * nulls
  An array describing which parameters are null. Must have same length as the plan’s number of arguments. n indicates a null value (entry in values will be ignored); a space indicates a nonnull value (entry in values is valid).

If nulls is NULL then SPI_cursor_open assumes that no parameters are null.

bool read_only
  true for read-only execution

RETURN VALUE

pointer to portal containing the cursor, or NULL on error


SPI_cursor_open () 2010-12-14
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