This page in other versions: 9.0 / 9.1 / 9.2 / 9.3 / 9.4  |  Development versions: devel  |  Unsupported versions: 7.1 / 7.2 / 7.3 / 7.4 / 8.0 / 8.1 / 8.2 / 8.3 / 8.4

Chapter 17. Server Programming Interface

Table of Contents
17.1. Interface Functions
SPI_connect --  Connects your procedure to the SPI manager.
SPI_finish --  Disconnects your procedure from the SPI manager.
SPI_exec --  Creates an execution plan (parser+planner+optimizer) and executes a query.
SPI_prepare --  Prepares a plan for a query, without executing it yet
SPI_execp -- Executes a plan from SPI_prepare
SPI_cursor_open -- Sets up a cursor using a plan created with SPI_prepare
SPI_cursor_find -- Finds an existing cursor (Portal) by name
SPI_cursor_fetch -- Fetches some rows from a cursor
SPI_cursor_move -- Moves a cursor
SPI_cursor_close -- Closes a cursor
SPI_saveplan --  Saves a passed plan
17.2. Interface Support Functions
SPI_fnumber -- Finds the attribute number for specified attribute name
SPI_fname -- Finds the attribute name for the specified attribute number
SPI_getvalue -- Returns the string value of the specified attribute
SPI_getbinval -- Returns the binary value of the specified attribute
SPI_gettype -- Returns the type name of the specified attribute
SPI_gettypeid -- Returns the type OID of the specified attribute
SPI_getrelname -- Returns the name of the specified relation
17.3. Memory Management
SPI_copytuple -- Makes copy of tuple in upper Executor context
SPI_copytupledesc -- Makes copy of tuple descriptor in upper Executor context
SPI_copytupleintoslot -- Makes copy of tuple and descriptor in upper Executor context
SPI_modifytuple -- Creates a tuple by replacing selected fields of a given tuple
SPI_palloc -- Allocates memory in upper Executor context
SPI_repalloc -- Re-allocates memory in upper Executor context
SPI_pfree -- Frees memory in upper Executor context
SPI_freetuple -- Frees a tuple allocated in upper Executor context
SPI_freetuptable -- Frees a tuple set created by SPI_exec or similar function
SPI_freeplan --  Releases a previously saved plan
17.4. Visibility of Data Changes
17.5. Examples

The Server Programming Interface (SPI) gives users the ability to run SQL queries inside user-defined C functions.

Note: The available Procedural Languages (PL) give an alternate means to build functions that can execute queries.

In fact, SPI is just a set of native interface functions to simplify access to the Parser, Planner, Optimizer and Executor. SPI also does some memory management.

To avoid misunderstanding we'll use function to mean SPI interface functions and procedure for user-defined C-functions using SPI.

Procedures which use SPI are called by the Executor. The SPI calls recursively invoke the Executor in turn to run queries. When the Executor is invoked recursively, it may itself call procedures which may make SPI calls.

Note that if during execution of a query from a procedure the transaction is aborted, then control will not be returned to your procedure. Rather, all work will be rolled back and the server will wait for the next command from the client. This will probably be changed in future versions.

A related restriction is the inability to execute BEGIN, END and ABORT (transaction control statements). This will also be changed in the future.

If successful, SPI functions return a non-negative result (either via a returned integer value or in SPI_result global variable, as described below). On error, a negative or NULL result will be returned.

17.1. Interface Functions

Table of Contents
SPI_connect --  Connects your procedure to the SPI manager.
SPI_finish --  Disconnects your procedure from the SPI manager.
SPI_exec --  Creates an execution plan (parser+planner+optimizer) and executes a query.
SPI_prepare --  Prepares a plan for a query, without executing it yet
SPI_execp -- Executes a plan from SPI_prepare
SPI_cursor_open -- Sets up a cursor using a plan created with SPI_prepare
SPI_cursor_find -- Finds an existing cursor (Portal) by name
SPI_cursor_fetch -- Fetches some rows from a cursor
SPI_cursor_move -- Moves a cursor
SPI_cursor_close -- Closes a cursor
SPI_saveplan --  Saves a passed plan
Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group