Chapter 46. Server Programming Interface

Chapter 46. Server Programming Interface
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Table of Contents

46.1. Interface Functions

SPI_connect - connect a C function to the SPI manager
SPI_finish - disconnect a C function from the SPI manager
SPI_execute - execute a command
SPI_exec - execute a read/write command
SPI_execute_with_args - execute a command with out-of-line parameters
SPI_prepare - prepare a statement, without executing it yet
SPI_prepare_cursor - prepare a statement, without executing it yet
SPI_prepare_params - prepare a statement, without executing it yet
SPI_getargcount - return the number of arguments needed by a statement prepared by SPI_prepare
SPI_getargtypeid - return the data type OID for an argument of a statement prepared by SPI_prepare
SPI_is_cursor_plan - return true if a statement prepared by SPI_prepare can be used with SPI_cursor_open
SPI_execute_plan - execute a statement prepared by SPI_prepare
SPI_execute_plan_with_paramlist - execute a statement prepared by SPI_prepare
SPI_execp - execute a statement in read/write mode
SPI_cursor_open - set up a cursor using a statement created with SPI_prepare
SPI_cursor_open_with_args - set up a cursor using a query and parameters
SPI_cursor_open_with_paramlist - set up a cursor using parameters
SPI_cursor_find - find an existing cursor by name
SPI_cursor_fetch - fetch some rows from a cursor
SPI_cursor_move - move a cursor
SPI_scroll_cursor_fetch - fetch some rows from a cursor
SPI_scroll_cursor_move - move a cursor
SPI_cursor_close - close a cursor
SPI_keepplan - save a prepared statement
SPI_saveplan - save a prepared statement
SPI_register_relation - make an ephemeral named relation available by name in SPI queries
SPI_unregister_relation - remove an ephemeral named relation from the registry
SPI_register_trigger_data - make ephemeral trigger data available in SPI queries

46.2. Interface Support Functions

SPI_fname - determine the column name for the specified column number
SPI_fnumber - determine the column number for the specified column name
SPI_getvalue - return the string value of the specified column
SPI_getbinval - return the binary value of the specified column
SPI_gettype - return the data type name of the specified column
SPI_gettypeid - return the data type OID of the specified column
SPI_getrelname - return the name of the specified relation
SPI_getnspname - return the namespace of the specified relation
SPI_result_code_string - return error code as string

46.3. Memory Management

SPI_palloc - allocate memory in the upper executor context
SPI_repalloc - reallocate memory in the upper executor context
SPI_pfree - free memory in the upper executor context
SPI_copytuple - make a copy of a row in the upper executor context
SPI_returntuple - prepare to return a tuple as a Datum
SPI_modifytuple - create a row by replacing selected fields of a given row
SPI_freetuple - free a row allocated in the upper executor context
SPI_freetuptable - free a row set created by SPI_execute or a similar function
SPI_freeplan - free a previously saved prepared statement

46.4. Transaction Management

SPI_commit - commit the current transaction
SPI_rollback - abort the current transaction
SPI_start_transaction - start a new transaction

46.5. Visibility of Data Changes

46.6. Examples

The Server Programming Interface ( SPI ) gives writers of user-defined C functions the ability to run SQL commands inside their functions or procedures. SPI is a set of interface functions to simplify access to the parser, planner, and executor. SPI also does some memory management.

Note

The available procedural languages provide various means to execute SQL commands from functions. Most of these facilities are based on SPI, so this documentation might be of use for users of those languages as well.

Note that if a command invoked via SPI fails, then control will not be returned to your C function. Rather, the transaction or subtransaction in which your C function executes will be rolled back. (This might seem surprising given that the SPI functions mostly have documented error-return conventions. Those conventions only apply for errors detected within the SPI functions themselves, however.) It is possible to recover control after an error by establishing your own subtransaction surrounding SPI calls that might fail.

SPI functions return a nonnegative result on success (either via a returned integer value or in the global variable SPI_result , as described below). On error, a negative result or NULL will be returned.

Source code files that use SPI must include the header file executor/spi.h .

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45.11. Environment Variables	Home	46.1. Interface Functions