src/include/executor/spi_priv.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * spi_priv.h
   4  *                              Server Programming Interface private declarations
   5  *
   6  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  * $PostgreSQL$
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 #ifndef SPI_PRIV_H
  14 #define SPI_PRIV_H
  15
  16 #include "executor/spi.h"
  17
  18
  19 #define _SPI_PLAN_MAGIC         569278163
  20
  21 typedef struct
  22 {
  23         /* current results */
  24         uint32          processed;              /* by Executor */
  25         Oid                     lastoid;
  26         SPITupleTable *tuptable;
  27
  28         MemoryContext procCxt;          /* procedure context */
  29         MemoryContext execCxt;          /* executor context */
  30         MemoryContext savedcxt;         /* context of SPI_connect's caller */
  31         SubTransactionId connectSubid;          /* ID of connecting subtransaction */
  32 } _SPI_connection;
  33
  34 /*
  35  * SPI plans have two states: saved or unsaved.
  36  *
  37  * For an unsaved plan, the _SPI_plan struct and all its subsidiary data are in
  38  * a dedicated memory context identified by plancxt.  An unsaved plan is good
  39  * at most for the current transaction, since the locks that protect it from
  40  * schema changes will be lost at end of transaction.  Hence the plancxt is
  41  * always a transient one.
  42  *
  43  * For a saved plan, the _SPI_plan struct and the argument type array are in
  44  * the plancxt (which can be really small).  All the other subsidiary state
  45  * is in plancache entries identified by plancache_list (note: the list cells
  46  * themselves are in plancxt).  We rely on plancache.c to keep the cache
  47  * entries up-to-date as needed.  The plancxt is a child of CacheMemoryContext
  48  * since it should persist until explicitly destroyed.
  49  *
  50  * To avoid redundant coding, the representation of unsaved plans matches
  51  * that of saved plans, ie, plancache_list is a list of CachedPlanSource
  52  * structs which in turn point to CachedPlan structs.  However, in an unsaved
  53  * plan all these structs are just created by spi.c and are not known to
  54  * plancache.c.  We don't try very hard to make all their fields valid,
  55  * only the ones spi.c actually uses.
  56  *
  57  * Note: if the original query string contained only whitespace and comments,
  58  * the plancache_list will be NIL and so there is no place to store the
  59  * query string.  We don't care about that, but we do care about the
  60  * argument type array, which is why it's seemingly-redundantly stored.
  61  */
  62 typedef struct _SPI_plan
  63 {
  64         int                     magic;                  /* should equal _SPI_PLAN_MAGIC */
  65         bool            saved;                  /* saved or unsaved plan? */
  66         List       *plancache_list; /* one CachedPlanSource per parsetree */
  67         MemoryContext plancxt;          /* Context containing _SPI_plan and data */
  68         int                     cursor_options; /* Cursor options used for planning */
  69         int                     nargs;                  /* number of plan arguments */
  70         Oid                *argtypes;           /* Argument types (NULL if nargs is 0) */
  71 } _SPI_plan;
  72
  73 #endif   /* SPI_PRIV_H */