src/include/tcop/utility.h

/*-------------------------------------------------------------------------
 *
 * utility.h
 *	  prototypes for utility.c.
 *
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/tcop/utility.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef UTILITY_H
#define UTILITY_H

#include "tcop/cmdtag.h"
#include "tcop/tcopprot.h"

typedef enum
{
	PROCESS_UTILITY_TOPLEVEL,	/* toplevel interactive command */
	PROCESS_UTILITY_QUERY,		/* a complete query, but not toplevel */
	PROCESS_UTILITY_QUERY_NONATOMIC,	/* a complete query, nonatomic
										 * execution context */
	PROCESS_UTILITY_SUBCOMMAND	/* a portion of a query */
} ProcessUtilityContext;

/* Info needed when recursing from ALTER TABLE */
typedef struct AlterTableUtilityContext
{
	PlannedStmt *pstmt;			/* PlannedStmt for outer ALTER TABLE command */
	const char *queryString;	/* its query string */
	Oid			relid;			/* OID of ALTER's target table */
	ParamListInfo params;		/* any parameters available to ALTER TABLE */
	QueryEnvironment *queryEnv; /* execution environment for ALTER TABLE */
} AlterTableUtilityContext;

/*
 * These constants are used to describe the extent to which a particular
 * command is read-only.
 *
 * COMMAND_OK_IN_READ_ONLY_TXN means that the command is permissible even when
 * XactReadOnly is set. This bit should be set for commands that don't change
 * the state of the database (data or schema) in a way that would affect the
 * output of pg_dump.
 *
 * COMMAND_OK_IN_PARALLEL_MODE means that the command is permissible even
 * when in parallel mode. Writing tuples is forbidden, as is anything that
 * might confuse cooperating processes.
 *
 * COMMAND_OK_IN_RECOVERY means that the command is permissible even when in
 * recovery. It can't write WAL, nor can it do things that would imperil
 * replay of future WAL received from the primary.
 */
#define COMMAND_OK_IN_READ_ONLY_TXN	0x0001
#define COMMAND_OK_IN_PARALLEL_MODE	0x0002
#define	COMMAND_OK_IN_RECOVERY		0x0004

/*
 * We say that a command is strictly read-only if it is sufficiently read-only
 * for all purposes. For clarity, we also have a constant for commands that are
 * in no way read-only.
 */
#define COMMAND_IS_STRICTLY_READ_ONLY \
	(COMMAND_OK_IN_READ_ONLY_TXN | COMMAND_OK_IN_RECOVERY | \
	 COMMAND_OK_IN_PARALLEL_MODE)
#define COMMAND_IS_NOT_READ_ONLY	0

/* Hook for plugins to get control in ProcessUtility() */
typedef void (*ProcessUtility_hook_type) (PlannedStmt *pstmt,
										  const char *queryString,
										  bool readOnlyTree,
										  ProcessUtilityContext context,
										  ParamListInfo params,
										  QueryEnvironment *queryEnv,
										  DestReceiver *dest, QueryCompletion *qc);
extern PGDLLIMPORT ProcessUtility_hook_type ProcessUtility_hook;

extern void ProcessUtility(PlannedStmt *pstmt, const char *queryString,
						   bool readOnlyTree,
						   ProcessUtilityContext context, ParamListInfo params,
						   QueryEnvironment *queryEnv,
						   DestReceiver *dest, QueryCompletion *qc);
extern void standard_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
									bool readOnlyTree,
									ProcessUtilityContext context, ParamListInfo params,
									QueryEnvironment *queryEnv,
									DestReceiver *dest, QueryCompletion *qc);

extern void ProcessUtilityForAlterTable(Node *stmt,
										AlterTableUtilityContext *context);

extern bool UtilityReturnsTuples(Node *parsetree);

extern TupleDesc UtilityTupleDescriptor(Node *parsetree);

extern Query *UtilityContainsQuery(Node *parsetree);

extern CommandTag CreateCommandTag(Node *parsetree);

static inline const char *
CreateCommandName(Node *parsetree)
{
	return GetCommandTagName(CreateCommandTag(parsetree));
}

extern LogStmtLevel GetCommandLogLevel(Node *parsetree);

extern bool CommandIsReadOnly(PlannedStmt *pstmt);

extern bool utility_nested(void);

#endif							/* UTILITY_H */