117 lines
3.7 KiB
C
117 lines
3.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* toast_helper.h
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* Helper functions for table AMs implementing compressed or
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* out-of-line storage of varlena attributes.
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*
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* Copyright (c) 2000-2023, PostgreSQL Global Development Group
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*
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* src/include/access/toast_helper.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TOAST_HELPER_H
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#define TOAST_HELPER_H
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#include "utils/rel.h"
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/*
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* Information about one column of a tuple being toasted.
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*
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* NOTE: toast_action[i] can have these values:
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* ' ' default handling
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* TYPSTORAGE_PLAIN already processed --- don't touch it
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* TYPSTORAGE_EXTENDED incompressible, but OK to move off
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*
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* NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
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* toast_action[i] different from TYPSTORAGE_PLAIN.
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*/
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typedef struct
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{
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struct varlena *tai_oldexternal;
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int32 tai_size;
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uint8 tai_colflags;
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char tai_compression;
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} ToastAttrInfo;
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/*
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* Information about one tuple being toasted.
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*/
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typedef struct
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{
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/*
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* Before calling toast_tuple_init, the caller must initialize the
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* following fields. Each array must have a length equal to
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* ttc_rel->rd_att->natts. The ttc_oldvalues and ttc_oldisnull fields
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* should be NULL in the case of an insert.
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*/
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Relation ttc_rel; /* the relation that contains the tuple */
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Datum *ttc_values; /* values from the tuple columns */
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bool *ttc_isnull; /* null flags for the tuple columns */
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Datum *ttc_oldvalues; /* values from previous tuple */
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bool *ttc_oldisnull; /* null flags from previous tuple */
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/*
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* Before calling toast_tuple_init, the caller should set ttc_attr to
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* point to an array of ToastAttrInfo structures of a length equal to
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* ttc_rel->rd_att->natts. The contents of the array need not be
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* initialized. ttc_flags also does not need to be initialized.
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*/
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uint8 ttc_flags;
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ToastAttrInfo *ttc_attr;
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} ToastTupleContext;
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/*
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* Flags indicating the overall state of a TOAST operation.
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*
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* TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
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* to be deleted.
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*
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* TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
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*
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* TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
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*
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* TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
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* words, the toaster did something.
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*/
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#define TOAST_NEEDS_DELETE_OLD 0x0001
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#define TOAST_NEEDS_FREE 0x0002
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#define TOAST_HAS_NULLS 0x0004
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#define TOAST_NEEDS_CHANGE 0x0008
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/*
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* Flags indicating the status of a TOAST operation with respect to a
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* particular column.
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*
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* TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
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* column need to be deleted.
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*
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* TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
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* be freed.
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*
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* TOASTCOL_IGNORE indicates that the toaster should not further process
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* this column.
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*
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* TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
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* be incompressible, but could be moved out-of-line.
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*/
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#define TOASTCOL_NEEDS_DELETE_OLD TOAST_NEEDS_DELETE_OLD
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#define TOASTCOL_NEEDS_FREE TOAST_NEEDS_FREE
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#define TOASTCOL_IGNORE 0x0010
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#define TOASTCOL_INCOMPRESSIBLE 0x0020
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extern void toast_tuple_init(ToastTupleContext *ttc);
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extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
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bool for_compression,
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bool check_main);
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extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
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extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
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int options);
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extern void toast_tuple_cleanup(ToastTupleContext *ttc);
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extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
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bool is_speculative);
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#endif
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