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/*-------------------------------------------------------------------------
*
* toast_helper.h
* Helper functions for table AMs implementing compressed or
* out-of-line storage of varlena attributes.
*
* Copyright (c) 2000-2022, PostgreSQL Global Development Group
*
* src/include/access/toast_helper.h
*
*-------------------------------------------------------------------------
*/
#ifndef TOAST_HELPER_H
#define TOAST_HELPER_H
#include "utils/rel.h"
/*
* Information about one column of a tuple being toasted.
*
* NOTE: toast_action[i] can have these values:
* ' ' default handling
* TYPSTORAGE_PLAIN already processed --- don't touch it
* TYPSTORAGE_EXTENDED incompressible, but OK to move off
*
* NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
* toast_action[i] different from TYPSTORAGE_PLAIN.
*/
typedef struct
{
struct varlena *tai_oldexternal;
int32 tai_size;
uint8 tai_colflags;
char tai_compression;
} ToastAttrInfo;
/*
* Information about one tuple being toasted.
*/
typedef struct
{
/*
* Before calling toast_tuple_init, the caller must initialize the
* following fields. Each array must have a length equal to
* ttc_rel->rd_att->natts. The tts_oldvalues and tts_oldisnull fields
* should be NULL in the case of an insert.
*/
Relation ttc_rel; /* the relation that contains the tuple */
Datum *ttc_values; /* values from the tuple columns */
bool *ttc_isnull; /* null flags for the tuple columns */
Datum *ttc_oldvalues; /* values from previous tuple */
bool *ttc_oldisnull; /* null flags from previous tuple */
/*
* Before calling toast_tuple_init, the caller should set tts_attr to
* point to an array of ToastAttrInfo structures of a length equal to
* tts_rel->rd_att->natts. The contents of the array need not be
* initialized. ttc_flags also does not need to be initialized.
*/
uint8 ttc_flags;
ToastAttrInfo *ttc_attr;
} ToastTupleContext;
/*
* Flags indicating the overall state of a TOAST operation.
*
* TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
* to be deleted.
*
* TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
*
* TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
*
* TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
* words, the toaster did something.
*/
#define TOAST_NEEDS_DELETE_OLD 0x0001
#define TOAST_NEEDS_FREE 0x0002
#define TOAST_HAS_NULLS 0x0004
#define TOAST_NEEDS_CHANGE 0x0008
/*
* Flags indicating the status of a TOAST operation with respect to a
* particular column.
*
* TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
* column need to be deleted.
*
* TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
* be freed.
*
* TOASTCOL_IGNORE indicates that the toaster should not further process
* this column.
*
* TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
* be incompressible, but could be moved out-of-line.
*/
#define TOASTCOL_NEEDS_DELETE_OLD TOAST_NEEDS_DELETE_OLD
#define TOASTCOL_NEEDS_FREE TOAST_NEEDS_FREE
#define TOASTCOL_IGNORE 0x0010
#define TOASTCOL_INCOMPRESSIBLE 0x0020
extern void toast_tuple_init(ToastTupleContext *ttc);
extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
bool for_compression,
bool check_main);
extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
int options);
extern void toast_tuple_cleanup(ToastTupleContext *ttc);
extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
bool is_speculative);
#endif
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