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PostgreSQL Reference Manual - Volume 2 - Programming Guide
by The PostgreSQL Global Development Group
Paperback (6"x9"), 408 pages
ISBN 0954612035
RRP £19.95 ($34.95)

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13.1.13 SPI_cursor_open

Name

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

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

ISBN 0954612035PostgreSQL Reference Manual - Volume 2 - Programming GuideSee the print edition