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spi_priv.h
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1 /*-------------------------------------------------------------------------
2  *
3  * spi_priv.h
4  * Server Programming Interface private declarations
5  *
6  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * src/include/executor/spi_priv.h
10  *
11  *-------------------------------------------------------------------------
12  */
13 #ifndef SPI_PRIV_H
14 #define SPI_PRIV_H
15 
16 #include "executor/spi.h"
17 #include "utils/queryenvironment.h"
18 
19 
20 #define _SPI_PLAN_MAGIC 569278163
21 
22 typedef struct
23 {
24  /* current results */
25  uint64 processed; /* by Executor */
27  SPITupleTable *tuptable; /* tuptable currently being built */
28 
29  /* subtransaction in which current Executor call was started */
31 
32  /* resources of this execution context */
33  slist_head tuptables; /* list of all live SPITupleTables */
34  MemoryContext procCxt; /* procedure context */
35  MemoryContext execCxt; /* executor context */
36  MemoryContext savedcxt; /* context of SPI_connect's caller */
37  SubTransactionId connectSubid; /* ID of connecting subtransaction */
38  QueryEnvironment *queryEnv; /* query environment setup for SPI level */
40 
41 /*
42  * SPI plans have three states: saved, unsaved, or temporary.
43  *
44  * Ordinarily, the _SPI_plan struct itself as well as the argtypes array
45  * are in a dedicated memory context identified by plancxt (which can be
46  * really small). All the other subsidiary state is in plancache entries
47  * identified by plancache_list (note: the list cells themselves are in
48  * plancxt).
49  *
50  * In an unsaved plan, the plancxt as well as the plancache entries' contexts
51  * are children of the SPI procedure context, so they'll all disappear at
52  * function exit. plancache.c also knows that the plancache entries are
53  * "unsaved", so it doesn't link them into its global list; hence they do
54  * not respond to inval events. This is OK since we are presumably holding
55  * adequate locks to prevent other backends from messing with the tables.
56  *
57  * For a saved plan, the plancxt is made a child of CacheMemoryContext
58  * since it should persist until explicitly destroyed. Likewise, the
59  * plancache entries will be under CacheMemoryContext since we tell
60  * plancache.c to save them. We rely on plancache.c to keep the cache
61  * entries up-to-date as needed in the face of invalidation events.
62  *
63  * There are also "temporary" SPI plans, in which the _SPI_plan struct is
64  * not even palloc'd but just exists in some function's local variable.
65  * The plancache entries are unsaved and exist under the SPI executor context,
66  * while additional data such as argtypes and list cells is loose in the SPI
67  * executor context. Such plans can be identified by having plancxt == NULL.
68  *
69  * We can also have "one-shot" SPI plans (which are typically temporary,
70  * as described above). These are meant to be executed once and discarded,
71  * and various optimizations are made on the assumption of single use.
72  * Note in particular that the CachedPlanSources within such an SPI plan
73  * are not "complete" until execution.
74  *
75  * Note: if the original query string contained only whitespace and comments,
76  * the plancache_list will be NIL and so there is no place to store the
77  * query string. We don't care about that, but we do care about the
78  * argument type array, which is why it's seemingly-redundantly stored.
79  */
80 typedef struct _SPI_plan
81 {
82  int magic; /* should equal _SPI_PLAN_MAGIC */
83  bool saved; /* saved or unsaved plan? */
84  bool oneshot; /* one-shot plan? */
85  List *plancache_list; /* one CachedPlanSource per parsetree */
86  MemoryContext plancxt; /* Context containing _SPI_plan and data */
87  int cursor_options; /* Cursor options used for planning */
88  int nargs; /* number of plan arguments */
89  Oid *argtypes; /* Argument types (NULL if nargs is 0) */
90  ParserSetupHook parserSetup; /* alternative parameter spec method */
92 } _SPI_plan;
93 
94 #endif /* SPI_PRIV_H */
Oid * argtypes
Definition: spi_priv.h:89
List * plancache_list
Definition: spi_priv.h:85
int magic
Definition: spi_priv.h:82
SubTransactionId execSubid
Definition: spi_priv.h:30
uint32 SubTransactionId
Definition: c.h:449
unsigned int Oid
Definition: postgres_ext.h:31
SubTransactionId connectSubid
Definition: spi_priv.h:37
QueryEnvironment * queryEnv
Definition: spi_priv.h:38
SPITupleTable * tuptable
Definition: spi_priv.h:27
void(* ParserSetupHook)(struct ParseState *pstate, void *arg)
Definition: params.h:66
MemoryContext savedcxt
Definition: spi_priv.h:36
MemoryContext plancxt
Definition: spi_priv.h:86
MemoryContext procCxt
Definition: spi_priv.h:34
MemoryContext execCxt
Definition: spi_priv.h:35
bool saved
Definition: spi_priv.h:83
int nargs
Definition: spi_priv.h:88
uint64 processed
Definition: spi_priv.h:25
ParserSetupHook parserSetup
Definition: spi_priv.h:90
bool oneshot
Definition: spi_priv.h:84
struct _SPI_plan _SPI_plan
void * parserSetupArg
Definition: spi_priv.h:91
int cursor_options
Definition: spi_priv.h:87
Definition: pg_list.h:45
slist_head tuptables
Definition: spi_priv.h:33