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9d4649ca49
Backpatch-through: certain files through 9.3
95 lines
3.9 KiB
C
95 lines
3.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* spi_priv.h
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* Server Programming Interface private declarations
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*
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* Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/executor/spi_priv.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SPI_PRIV_H
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#define SPI_PRIV_H
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#include "executor/spi.h"
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#include "utils/queryenvironment.h"
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#define _SPI_PLAN_MAGIC 569278163
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typedef struct
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{
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/* current results */
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uint64 processed; /* by Executor */
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Oid lastoid;
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SPITupleTable *tuptable; /* tuptable currently being built */
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/* subtransaction in which current Executor call was started */
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SubTransactionId execSubid;
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/* resources of this execution context */
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slist_head tuptables; /* list of all live SPITupleTables */
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MemoryContext procCxt; /* procedure context */
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MemoryContext execCxt; /* executor context */
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MemoryContext savedcxt; /* context of SPI_connect's caller */
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SubTransactionId connectSubid; /* ID of connecting subtransaction */
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QueryEnvironment *queryEnv; /* query environment setup for SPI level */
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} _SPI_connection;
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/*
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* SPI plans have three states: saved, unsaved, or temporary.
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*
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* Ordinarily, the _SPI_plan struct itself as well as the argtypes array
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* are in a dedicated memory context identified by plancxt (which can be
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* really small). All the other subsidiary state is in plancache entries
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* identified by plancache_list (note: the list cells themselves are in
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* plancxt).
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*
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* In an unsaved plan, the plancxt as well as the plancache entries' contexts
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* are children of the SPI procedure context, so they'll all disappear at
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* function exit. plancache.c also knows that the plancache entries are
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* "unsaved", so it doesn't link them into its global list; hence they do
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* not respond to inval events. This is OK since we are presumably holding
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* adequate locks to prevent other backends from messing with the tables.
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*
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* For a saved plan, the plancxt is made a child of CacheMemoryContext
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* since it should persist until explicitly destroyed. Likewise, the
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* plancache entries will be under CacheMemoryContext since we tell
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* plancache.c to save them. We rely on plancache.c to keep the cache
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* entries up-to-date as needed in the face of invalidation events.
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*
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* There are also "temporary" SPI plans, in which the _SPI_plan struct is
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* not even palloc'd but just exists in some function's local variable.
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* The plancache entries are unsaved and exist under the SPI executor context,
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* while additional data such as argtypes and list cells is loose in the SPI
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* executor context. Such plans can be identified by having plancxt == NULL.
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*
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* We can also have "one-shot" SPI plans (which are typically temporary,
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* as described above). These are meant to be executed once and discarded,
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* and various optimizations are made on the assumption of single use.
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* Note in particular that the CachedPlanSources within such an SPI plan
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* are not "complete" until execution.
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*
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* Note: if the original query string contained only whitespace and comments,
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* the plancache_list will be NIL and so there is no place to store the
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* query string. We don't care about that, but we do care about the
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* argument type array, which is why it's seemingly-redundantly stored.
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*/
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typedef struct _SPI_plan
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{
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int magic; /* should equal _SPI_PLAN_MAGIC */
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bool saved; /* saved or unsaved plan? */
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bool oneshot; /* one-shot plan? */
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List *plancache_list; /* one CachedPlanSource per parsetree */
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MemoryContext plancxt; /* Context containing _SPI_plan and data */
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int cursor_options; /* Cursor options used for planning */
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int nargs; /* number of plan arguments */
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Oid *argtypes; /* Argument types (NULL if nargs is 0) */
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ParserSetupHook parserSetup; /* alternative parameter spec method */
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void *parserSetupArg;
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} _SPI_plan;
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#endif /* SPI_PRIV_H */
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