| /*------------------------------------------------------------------------- |
| * |
| * tuptoaster.h |
| * POSTGRES definitions for external and compressed storage |
| * of variable size attributes. |
| * |
| * Copyright (c) 2000-2009, PostgreSQL Global Development Group |
| * |
| * $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.28.2.1 2007/02/04 20:00:49 tgl Exp $ |
| * |
| *------------------------------------------------------------------------- |
| */ |
| #ifndef TUPTOASTER_H |
| #define TUPTOASTER_H |
| |
| #include "access/htup.h" |
| #include "access/memtup.h" |
| #include "storage/bufpage.h" |
| #include "utils/relcache.h" |
| |
| #ifndef VARSIZE_TO_SHORT |
| #define VARSIZE_TO_SHORT(PTR) ((char)(VARSIZE(PTR)-VARHDRSZ+VARHDRSZ_SHORT) | 0x80) |
| #define VARSIZE_TO_SHORT_D(D) VARSIZE_TO_SHORT(DatumGetPointer(D)) |
| #endif |
| |
| /* |
| * This enables de-toasting of index entries. Needed until VACUUM is |
| * smart enough to rebuild indexes from scratch. |
| */ |
| #define TOAST_INDEX_HACK |
| |
| |
| /* |
| * These symbols control toaster activation. If a tuple is larger than |
| * TOAST_TUPLE_THRESHOLD, we will try to toast it down to no more than |
| * TOAST_TUPLE_TARGET bytes. Both numbers include all tuple header overhead |
| * and between-fields alignment padding, but we do *not* consider any |
| * end-of-tuple alignment padding; hence the values can be compared directly |
| * to a tuple's t_len field. (Note that the symbol values are not |
| * necessarily MAXALIGN multiples.) |
| * |
| * The numbers need not be the same, though they currently are. |
| */ |
| #define TOAST_TUPLE_THRESHOLD (MaxHeapTupleSize / 4) |
| |
| #define TOAST_TUPLE_TARGET (MaxHeapTupleSize / 4) |
| |
| /* |
| * If an index value is larger than TOAST_INDEX_TARGET, we will try to |
| * compress it (we can't move it out-of-line, however). Note that this |
| * number is per-datum, not per-tuple, for simplicity in index_form_tuple(). |
| */ |
| #define TOAST_INDEX_TARGET (MaxHeapTupleSize / 16) |
| |
| /* |
| * When we store an oversize datum externally, we divide it into chunks |
| * containing at most TOAST_MAX_CHUNK_SIZE data bytes. This number *must* |
| * be small enough that the completed toast-table tuple (including the |
| * ID and sequence fields and all overhead) is no more than MaxHeapTupleSize |
| * bytes. It *should* be small enough to make toast-table tuples no more |
| * than TOAST_TUPLE_THRESHOLD bytes, else heapam.c will uselessly invoke |
| * the toaster on toast-table tuples. |
| * |
| * NB: you cannot change this value without forcing initdb, at least not |
| * if your DB contains any multi-chunk toasted values. |
| */ |
| #define TOAST_MAX_CHUNK_SIZE (TOAST_TUPLE_THRESHOLD - \ |
| MAXALIGN( \ |
| MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + \ |
| sizeof(Oid) + \ |
| sizeof(int32) + \ |
| VARHDRSZ)) |
| |
| /* ------- |
| * Convert internal struct to external format. |
| * The caller should call pfree() to free the returned pointer. |
| */ |
| extern struct varatt_external *copy_varatt_external(struct varlena *attr); |
| |
| /* ---------- |
| * toast_insert_or_update - |
| * |
| * Called by heap_insert() and heap_update(). |
| * |
| * 'isFrozen' is normally marked false. it is only true |
| * when we are interested in inserting it with FrozenTxnId |
| * such a scenario is when we insert into an error table. |
| * since the data itself is inserted as frozen, we need any |
| * toasted data to be inserted frozen as well. |
| * ---------- |
| */ |
| extern HeapTuple toast_insert_or_update(Relation rel, |
| HeapTuple newtup, HeapTuple oldtup, |
| MemTupleBinding *pbind, int toast_tuple_target, |
| bool isFrozen); |
| |
| /* ---------- |
| * toast_delete - |
| * |
| * Called by heap_delete(). |
| * ---------- |
| */ |
| extern void toast_delete(Relation rel, HeapTuple oldtup); |
| |
| /* ---------- |
| * heap_tuple_fetch_attr() - |
| * |
| * Fetches an external stored attribute from the toast |
| * relation. Does NOT decompress it, if stored external |
| * in compressed format. |
| * ---------- |
| */ |
| extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr); |
| |
| /* ---------- |
| * varattrib_untoast_ptr_len |
| * |
| * Fast path to get the pointer and length, avoid palloc if possible. |
| * ---------- |
| */ |
| extern void varattrib_untoast_ptr_len(Datum d, char **datastart, int *len, void **tofree); |
| |
| /* ---------- |
| * varattrib_untoast_len |
| * |
| * Fast path to get the length, avoid palloc if possible. |
| * ---------- |
| */ |
| extern int varattrib_untoast_len(Datum d); |
| |
| /* ---------- |
| * heap_tuple_untoast_attr() - |
| * |
| * Fully detoasts one attribute, fetching and/or decompressing |
| * it as needed. |
| * ---------- |
| */ |
| extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr); |
| |
| /* ---------- |
| * heap_tuple_untoast_attr_slice() - |
| * |
| * Fetches only the specified portion of an attribute. |
| * (Handles all cases for attribute storage) |
| * ---------- |
| */ |
| extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr, |
| int32 sliceoffset, |
| int32 slicelength); |
| |
| /* ---------- |
| * toast_flatten_tuple_attribute - |
| * |
| * If a Datum is of composite type, "flatten" it to contain no toasted fields. |
| * This must be invoked on any potentially-composite field that is to be |
| * inserted into a tuple. Doing this preserves the invariant that toasting |
| * goes only one level deep in a tuple. |
| * ---------- |
| */ |
| extern Datum toast_flatten_tuple_attribute(Datum value, |
| Oid typeId, int32 typeMod); |
| |
| /* ---------- |
| * toast_compress_datum - |
| * |
| * Create a compressed version of a varlena datum, if possible |
| * ---------- |
| */ |
| extern Datum toast_compress_datum(Datum value); |
| |
| /* ---------- |
| * toast_raw_datum_size - |
| * |
| * Return the raw (detoasted) size of a varlena datum |
| * ---------- |
| */ |
| extern Size toast_raw_datum_size(Datum value); |
| |
| /* ---------- |
| * toast_datum_size - |
| * |
| * Return the storage size of a varlena datum |
| * ---------- |
| */ |
| extern Size toast_datum_size(Datum value); |
| |
| #endif /* TUPTOASTER_H */ |
