| SPI_cursor_open(3) - phpMan
SPI_CURSOR_OPEN(3) PostgreSQL 12.3 Documentation SPI_CURSOR_OPEN(3)
NAME
SPI_cursor_open - set up a cursor using a statement created with SPI_prepare
SYNOPSIS
Portal SPI_cursor_open(const char * name, SPIPlanPtr plan,
Datum * values, const char * nulls,
bool read_only)
DESCRIPTION
SPI_cursor_open sets up a cursor (internally, a portal) that will execute a statement
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 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 C function (it can, in fact,
live to the end of the current transaction). Returning the portal name to the C function's
caller provides a way of returning a row set as result.
The passed-in parameter data will be copied into the cursor's portal, so it can be freed
while the cursor still exists.
ARGUMENTS
const char * name
name for portal, or NULL to let the system select a name
SPIPlanPtr plan
prepared statement (returned by SPI_prepare)
Datum * values
An array of actual parameter values. Must have same length as the statement's number
of arguments.
const char * nulls
An array describing which parameters are null. Must have same length as the
statement's number of arguments.
If nulls is NULL then SPI_cursor_open assumes that no parameters are null. Otherwise,
each entry of the nulls array should be ' ' if the corresponding parameter value is
non-null, or 'n' if the corresponding parameter value is null. (In the latter case,
the actual value in the corresponding values entry doesn't matter.) Note that nulls is
not a text string, just an array: it does not need a '\0' terminator.
bool read_only
true for read-only execution
RETURN VALUE
Pointer to portal containing the cursor. Note there is no error return convention; any
error will be reported via elog.
PostgreSQL 12.3 2020 SPI_CURSOR_OPEN(3)
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