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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) 1996-2019, 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 */
26  SPITupleTable *tuptable; /* tuptable currently being built */
27 
28  /* subtransaction in which current Executor call was started */
30 
31  /* resources of this execution context */
32  slist_head tuptables; /* list of all live SPITupleTables */
33  MemoryContext procCxt; /* procedure context */
34  MemoryContext execCxt; /* executor context */
35  MemoryContext savedcxt; /* context of SPI_connect's caller */
36  SubTransactionId connectSubid; /* ID of connecting subtransaction */
37  QueryEnvironment *queryEnv; /* query environment setup for SPI level */
38 
39  /* transaction management support */
40  bool atomic; /* atomic execution context, does not allow
41  * transactions */
42  bool internal_xact; /* SPI-managed transaction boundary, skip
43  * cleanup */
44 
45  /* saved values of API global variables for previous nesting level */
50 
51 /*
52  * SPI plans have three states: saved, unsaved, or temporary.
53  *
54  * Ordinarily, the _SPI_plan struct itself as well as the argtypes array
55  * are in a dedicated memory context identified by plancxt (which can be
56  * really small). All the other subsidiary state is in plancache entries
57  * identified by plancache_list (note: the list cells themselves are in
58  * plancxt).
59  *
60  * In an unsaved plan, the plancxt as well as the plancache entries' contexts
61  * are children of the SPI procedure context, so they'll all disappear at
62  * function exit. plancache.c also knows that the plancache entries are
63  * "unsaved", so it doesn't link them into its global list; hence they do
64  * not respond to inval events. This is OK since we are presumably holding
65  * adequate locks to prevent other backends from messing with the tables.
66  *
67  * For a saved plan, the plancxt is made a child of CacheMemoryContext
68  * since it should persist until explicitly destroyed. Likewise, the
69  * plancache entries will be under CacheMemoryContext since we tell
70  * plancache.c to save them. We rely on plancache.c to keep the cache
71  * entries up-to-date as needed in the face of invalidation events.
72  *
73  * There are also "temporary" SPI plans, in which the _SPI_plan struct is
74  * not even palloc'd but just exists in some function's local variable.
75  * The plancache entries are unsaved and exist under the SPI executor context,
76  * while additional data such as argtypes and list cells is loose in the SPI
77  * executor context. Such plans can be identified by having plancxt == NULL.
78  *
79  * We can also have "one-shot" SPI plans (which are typically temporary,
80  * as described above). These are meant to be executed once and discarded,
81  * and various optimizations are made on the assumption of single use.
82  * Note in particular that the CachedPlanSources within such an SPI plan
83  * are not "complete" until execution.
84  *
85  * Note: if the original query string contained only whitespace and comments,
86  * the plancache_list will be NIL and so there is no place to store the
87  * query string. We don't care about that, but we do care about the
88  * argument type array, which is why it's seemingly-redundantly stored.
89  */
90 typedef struct _SPI_plan
91 {
92  int magic; /* should equal _SPI_PLAN_MAGIC */
93  bool saved; /* saved or unsaved plan? */
94  bool oneshot; /* one-shot plan? */
95  bool no_snapshots; /* let the caller handle the snapshots */
96  List *plancache_list; /* one CachedPlanSource per parsetree */
97  MemoryContext plancxt; /* Context containing _SPI_plan and data */
98  int cursor_options; /* Cursor options used for planning */
99  int nargs; /* number of plan arguments */
100  Oid *argtypes; /* Argument types (NULL if nargs is 0) */
101  ParserSetupHook parserSetup; /* alternative parameter spec method */
103 } _SPI_plan;
104 
105 #endif /* SPI_PRIV_H */
Oid * argtypes
Definition: spi_priv.h:100
List * plancache_list
Definition: spi_priv.h:96
bool internal_xact
Definition: spi_priv.h:42
int magic
Definition: spi_priv.h:92
SubTransactionId execSubid
Definition: spi_priv.h:29
uint32 SubTransactionId
Definition: c.h:512
unsigned int Oid
Definition: postgres_ext.h:31
SPITupleTable * outer_tuptable
Definition: spi_priv.h:47
SubTransactionId connectSubid
Definition: spi_priv.h:36
bool no_snapshots
Definition: spi_priv.h:95
QueryEnvironment * queryEnv
Definition: spi_priv.h:37
SPITupleTable * tuptable
Definition: spi_priv.h:26
void(* ParserSetupHook)(struct ParseState *pstate, void *arg)
Definition: params.h:108
MemoryContext savedcxt
Definition: spi_priv.h:35
MemoryContext plancxt
Definition: spi_priv.h:97
uint64 outer_processed
Definition: spi_priv.h:46
MemoryContext procCxt
Definition: spi_priv.h:33
MemoryContext execCxt
Definition: spi_priv.h:34
bool saved
Definition: spi_priv.h:93
int nargs
Definition: spi_priv.h:99
uint64 processed
Definition: spi_priv.h:25
int outer_result
Definition: spi_priv.h:48
ParserSetupHook parserSetup
Definition: spi_priv.h:101
bool oneshot
Definition: spi_priv.h:94
struct _SPI_plan _SPI_plan
void * parserSetupArg
Definition: spi_priv.h:102
int cursor_options
Definition: spi_priv.h:98
Definition: pg_list.h:50
slist_head tuptables
Definition: spi_priv.h:32