Provided by: postgresql-doc-10_10.23-0ubuntu0.18.04.2_all 
NAME
SPI_keepplan - save a prepared statement
SYNOPSIS
int SPI_keepplan(SPIPlanPtr plan)
DESCRIPTION
SPI_keepplan saves a passed statement (prepared by SPI_prepare) so that it will not be freed by
SPI_finish nor by the transaction manager. This gives you the ability to reuse prepared statements in the
subsequent invocations of your procedure in the current session.
ARGUMENTS
SPIPlanPtr plan
the prepared statement to be saved
RETURN VALUE
0 on success; SPI_ERROR_ARGUMENT if plan is NULL or invalid
NOTES
The passed-in statement is relocated to permanent storage by means of pointer adjustment (no data copying
is required). If you later wish to delete it, use SPI_freeplan on it.