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f8c4d7db60
unnecessary #include lines in it. Also, move some tuple routine prototypes and macros to htup.h, which allows removal of heapam.h inclusion from some .c files. For this to work, a new header file access/sysattr.h needed to be created, initially containing attribute numbers of system columns, for pg_dump usage. While at it, make contrib ltree, intarray and hstore header files more consistent with our header style.
174 lines
5.3 KiB
C
174 lines
5.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* tuptoaster.h
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* POSTGRES definitions for external and compressed storage
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* of variable size attributes.
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*
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* Copyright (c) 2000-2008, PostgreSQL Global Development Group
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*
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* $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.39 2008/05/12 00:00:53 alvherre Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TUPTOASTER_H
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#define TUPTOASTER_H
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#include "access/htup.h"
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#include "storage/bufpage.h"
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#include "utils/rel.h"
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/*
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* This enables de-toasting of index entries. Needed until VACUUM is
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* smart enough to rebuild indexes from scratch.
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*/
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#define TOAST_INDEX_HACK
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/*
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* These symbols control toaster activation. If a tuple is larger than
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* TOAST_TUPLE_THRESHOLD, we will try to toast it down to no more than
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* TOAST_TUPLE_TARGET bytes. Both numbers include all tuple header overhead
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* and between-fields alignment padding, but we do *not* consider any
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* end-of-tuple alignment padding; hence the values can be compared directly
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* to a tuple's t_len field.
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*
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* The numbers need not be the same, though they currently are. It doesn't
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* make sense for TARGET to exceed THRESHOLD, but it could be useful to make
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* it be smaller.
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*
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* Currently we choose both values to match the largest tuple size for which
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* TOAST_TUPLES_PER_PAGE tuples can fit on a disk page.
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*
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* XXX while these can be modified without initdb, some thought needs to be
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* given to needs_toast_table() in toasting.c before unleashing random
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* changes. Also see LOBLKSIZE in large_object.h, which can *not* be
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* changed without initdb.
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*/
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#define TOAST_TUPLES_PER_PAGE 4
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/* Note: sizeof(PageHeaderData) includes the first ItemId on the page */
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#define TOAST_TUPLE_THRESHOLD \
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MAXALIGN_DOWN((BLCKSZ - \
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MAXALIGN(sizeof(PageHeaderData) + (TOAST_TUPLES_PER_PAGE-1) * sizeof(ItemIdData))) \
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/ TOAST_TUPLES_PER_PAGE)
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#define TOAST_TUPLE_TARGET TOAST_TUPLE_THRESHOLD
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/*
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* If an index value is larger than TOAST_INDEX_TARGET, we will try to
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* compress it (we can't move it out-of-line, however). Note that this
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* number is per-datum, not per-tuple, for simplicity in index_form_tuple().
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*/
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#define TOAST_INDEX_TARGET (MaxHeapTupleSize / 16)
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/*
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* When we store an oversize datum externally, we divide it into chunks
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* containing at most TOAST_MAX_CHUNK_SIZE data bytes. This number *must*
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* be small enough that the completed toast-table tuple (including the
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* ID and sequence fields and all overhead) will fit on a page.
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* The coding here sets the size on the theory that we want to fit
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* EXTERN_TUPLES_PER_PAGE tuples of maximum size onto a page.
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*
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* NB: Changing TOAST_MAX_CHUNK_SIZE requires an initdb.
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*/
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#define EXTERN_TUPLES_PER_PAGE 4 /* tweak only this */
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/* Note: sizeof(PageHeaderData) includes the first ItemId on the page */
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#define EXTERN_TUPLE_MAX_SIZE \
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MAXALIGN_DOWN((BLCKSZ - \
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MAXALIGN(sizeof(PageHeaderData) + (EXTERN_TUPLES_PER_PAGE-1) * sizeof(ItemIdData))) \
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/ EXTERN_TUPLES_PER_PAGE)
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#define TOAST_MAX_CHUNK_SIZE \
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(EXTERN_TUPLE_MAX_SIZE - \
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MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) - \
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sizeof(Oid) - \
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sizeof(int32) - \
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VARHDRSZ)
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/* ----------
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* toast_insert_or_update -
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*
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* Called by heap_insert() and heap_update().
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* ----------
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*/
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extern HeapTuple toast_insert_or_update(Relation rel,
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HeapTuple newtup, HeapTuple oldtup,
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bool use_wal, bool use_fsm);
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/* ----------
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* toast_delete -
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*
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* Called by heap_delete().
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* ----------
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*/
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extern void toast_delete(Relation rel, HeapTuple oldtup);
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/* ----------
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* heap_tuple_fetch_attr() -
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*
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* Fetches an external stored attribute from the toast
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* relation. Does NOT decompress it, if stored external
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* in compressed format.
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* ----------
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*/
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extern struct varlena *heap_tuple_fetch_attr(struct varlena * attr);
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/* ----------
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* heap_tuple_untoast_attr() -
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*
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* Fully detoasts one attribute, fetching and/or decompressing
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* it as needed.
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* ----------
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*/
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extern struct varlena *heap_tuple_untoast_attr(struct varlena * attr);
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/* ----------
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* heap_tuple_untoast_attr_slice() -
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*
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* Fetches only the specified portion of an attribute.
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* (Handles all cases for attribute storage)
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* ----------
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*/
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extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena * attr,
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int32 sliceoffset,
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int32 slicelength);
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/* ----------
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* toast_flatten_tuple_attribute -
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*
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* If a Datum is of composite type, "flatten" it to contain no toasted fields.
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* This must be invoked on any potentially-composite field that is to be
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* inserted into a tuple. Doing this preserves the invariant that toasting
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* goes only one level deep in a tuple.
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* ----------
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*/
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extern Datum toast_flatten_tuple_attribute(Datum value,
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Oid typeId, int32 typeMod);
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/* ----------
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* toast_compress_datum -
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*
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* Create a compressed version of a varlena datum, if possible
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* ----------
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*/
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extern Datum toast_compress_datum(Datum value);
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/* ----------
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* toast_raw_datum_size -
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*
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* Return the raw (detoasted) size of a varlena datum
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* ----------
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*/
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extern Size toast_raw_datum_size(Datum value);
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/* ----------
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* toast_datum_size -
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*
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* Return the storage size of a varlena datum
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* ----------
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*/
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extern Size toast_datum_size(Datum value);
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#endif /* TUPTOASTER_H */
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