1 /*-------------------------------------------------------------------------
4 * Server Programming Interface private declarations
6 * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
9 * src/include/executor/spi_priv.h
11 *-------------------------------------------------------------------------
16 #include "executor/spi.h"
19 #define _SPI_PLAN_MAGIC 569278163
24 uint32 processed; /* by Executor */
26 SPITupleTable *tuptable; /* tuptable currently being built */
28 /* resources of this execution context */
29 slist_head tuptables; /* list of all live SPITupleTables */
30 MemoryContext procCxt; /* procedure context */
31 MemoryContext execCxt; /* executor context */
32 MemoryContext savedcxt; /* context of SPI_connect's caller */
33 SubTransactionId connectSubid; /* ID of connecting subtransaction */
37 * SPI plans have three states: saved, unsaved, or temporary.
39 * Ordinarily, the _SPI_plan struct itself as well as the argtypes array
40 * are in a dedicated memory context identified by plancxt (which can be
41 * really small). All the other subsidiary state is in plancache entries
42 * identified by plancache_list (note: the list cells themselves are in
45 * In an unsaved plan, the plancxt as well as the plancache entries' contexts
46 * are children of the SPI procedure context, so they'll all disappear at
47 * function exit. plancache.c also knows that the plancache entries are
48 * "unsaved", so it doesn't link them into its global list; hence they do
49 * not respond to inval events. This is OK since we are presumably holding
50 * adequate locks to prevent other backends from messing with the tables.
52 * For a saved plan, the plancxt is made a child of CacheMemoryContext
53 * since it should persist until explicitly destroyed. Likewise, the
54 * plancache entries will be under CacheMemoryContext since we tell
55 * plancache.c to save them. We rely on plancache.c to keep the cache
56 * entries up-to-date as needed in the face of invalidation events.
58 * There are also "temporary" SPI plans, in which the _SPI_plan struct is
59 * not even palloc'd but just exists in some function's local variable.
60 * The plancache entries are unsaved and exist under the SPI executor context,
61 * while additional data such as argtypes and list cells is loose in the SPI
62 * executor context. Such plans can be identified by having plancxt == NULL.
64 * We can also have "one-shot" SPI plans (which are typically temporary,
65 * as described above). These are meant to be executed once and discarded,
66 * and various optimizations are made on the assumption of single use.
67 * Note in particular that the CachedPlanSources within such an SPI plan
68 * are not "complete" until execution.
70 * Note: if the original query string contained only whitespace and comments,
71 * the plancache_list will be NIL and so there is no place to store the
72 * query string. We don't care about that, but we do care about the
73 * argument type array, which is why it's seemingly-redundantly stored.
75 typedef struct _SPI_plan
77 int magic; /* should equal _SPI_PLAN_MAGIC */
78 bool saved; /* saved or unsaved plan? */
79 bool oneshot; /* one-shot plan? */
80 List *plancache_list; /* one CachedPlanSource per parsetree */
81 MemoryContext plancxt; /* Context containing _SPI_plan and data */
82 int cursor_options; /* Cursor options used for planning */
83 int nargs; /* number of plan arguments */
84 Oid *argtypes; /* Argument types (NULL if nargs is 0) */
85 ParserSetupHook parserSetup; /* alternative parameter spec method */
89 #endif /* SPI_PRIV_H */