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portal development
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SPI_CURSOR_OPEN(3) PostgreSQL 9.2.7 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 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. 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. 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. Note there is no error return convention; any error will be reported via elog. PostgreSQL 9.2.7 2014-02-17 SPI_CURSOR_OPEN(3)
