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compressible but not externally storable (since we're not sure about whether creating a toast relation for pg_class would work).
1070 lines
25 KiB
C
1070 lines
25 KiB
C
/*-------------------------------------------------------------------------
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*
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* tuptoaster.c
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* Support routines for external and compressed storage of
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* variable size attributes.
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*
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* Copyright (c) 2000, PostgreSQL Global Development Group
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.10 2000/07/31 22:39:17 tgl Exp $
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*
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*
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* INTERFACE ROUTINES
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* heap_tuple_toast_attrs -
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* Try to make a given tuple fit into one page by compressing
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* or moving off attributes
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*
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* heap_tuple_untoast_attr -
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* Fetch back a given value from the "secondary" relation
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*
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*-------------------------------------------------------------------------
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include "postgres.h"
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#include "access/heapam.h"
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#include "access/genam.h"
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#include "access/tuptoaster.h"
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#include "catalog/catalog.h"
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#include "utils/rel.h"
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#include "utils/builtins.h"
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#include "utils/fmgroids.h"
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#include "utils/pg_lzcompress.h"
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#ifdef TUPLE_TOASTER_ACTIVE
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#undef TOAST_DEBUG
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static void toast_delete(Relation rel, HeapTuple oldtup);
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static void toast_delete_datum(Relation rel, Datum value);
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static void toast_insert_or_update(Relation rel, HeapTuple newtup,
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HeapTuple oldtup);
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static Datum toast_compress_datum(Datum value);
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static Datum toast_save_datum(Relation rel, Oid mainoid, int16 attno, Datum value);
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static varattrib *toast_fetch_datum(varattrib *attr);
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/* ----------
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* heap_tuple_toast_attrs -
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*
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* This is the central public entry point for toasting from heapam.
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*
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* Calls the appropriate event specific action.
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* ----------
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*/
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void
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heap_tuple_toast_attrs(Relation rel, HeapTuple newtup, HeapTuple oldtup)
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{
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if (newtup == NULL)
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toast_delete(rel, oldtup);
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else
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toast_insert_or_update(rel, newtup, oldtup);
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}
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/* ----------
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* heap_tuple_fetch_attr -
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*
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* Public entry point to get back a toasted value
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* external storage (possibly still in compressed format).
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* ----------
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*/
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varattrib *
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heap_tuple_fetch_attr(varattrib *attr)
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{
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varattrib *result;
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if (VARATT_IS_EXTERNAL(attr))
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{
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/* ----------
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* This is an external stored plain value
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* ----------
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*/
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result = toast_fetch_datum(attr);
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}
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else
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{
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/* ----------
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* This is a plain value inside of the main tuple - why am I called?
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* ----------
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*/
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result = attr;
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}
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return result;
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}
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/* ----------
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* heap_tuple_untoast_attr -
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*
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* Public entry point to get back a toasted value from compression
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* or external storage.
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* ----------
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*/
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varattrib *
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heap_tuple_untoast_attr(varattrib *attr)
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{
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varattrib *result;
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if (VARATT_IS_EXTERNAL(attr))
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{
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if (VARATT_IS_COMPRESSED(attr))
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{
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/* ----------
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* This is an external stored compressed value
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* Fetch it from the toast heap and decompress.
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* ----------
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*/
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varattrib *tmp;
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tmp = toast_fetch_datum(attr);
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result = (varattrib *)palloc(attr->va_content.va_external.va_rawsize
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+ VARHDRSZ);
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VARATT_SIZEP(result) = attr->va_content.va_external.va_rawsize
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+ VARHDRSZ;
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pglz_decompress((PGLZ_Header *)tmp, VARATT_DATA(result));
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pfree(tmp);
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}
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else
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{
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/* ----------
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* This is an external stored plain value
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* ----------
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*/
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result = toast_fetch_datum(attr);
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}
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}
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else if (VARATT_IS_COMPRESSED(attr))
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{
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/* ----------
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* This is a compressed value inside of the main tuple
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* ----------
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*/
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result = (varattrib *)palloc(attr->va_content.va_compressed.va_rawsize
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+ VARHDRSZ);
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VARATT_SIZEP(result) = attr->va_content.va_compressed.va_rawsize
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+ VARHDRSZ;
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pglz_decompress((PGLZ_Header *)attr, VARATT_DATA(result));
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}
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else
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/* ----------
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* This is a plain value inside of the main tuple - why am I called?
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* ----------
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*/
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return attr;
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return result;
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}
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/* ----------
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* toast_delete -
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*
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* Cascaded delete toast-entries on DELETE
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* ----------
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*/
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static void
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toast_delete(Relation rel, HeapTuple oldtup)
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{
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TupleDesc tupleDesc;
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Form_pg_attribute *att;
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int numAttrs;
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int i;
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Datum value;
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bool isnull;
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/* ----------
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* Get the tuple descriptor, the number of and attribute
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* descriptors.
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* ----------
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*/
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tupleDesc = rel->rd_att;
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numAttrs = tupleDesc->natts;
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att = tupleDesc->attrs;
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/* ----------
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* Check for external stored attributes and delete them
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* from the secondary relation.
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* ----------
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*/
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for (i = 0; i < numAttrs; i++)
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{
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value = heap_getattr(oldtup, i + 1, tupleDesc, &isnull);
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if (!isnull && att[i]->attlen == -1)
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if (VARATT_IS_EXTERNAL(value))
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toast_delete_datum(rel, value);
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}
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}
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/* ----------
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* toast_insert_or_update -
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*
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* Delete no more used toast-entries and create new ones to
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* make the new tuple fit on INSERT or UPDATE
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* ----------
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*/
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static void
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toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup)
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{
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TupleDesc tupleDesc;
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Form_pg_attribute *att;
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int numAttrs;
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int i;
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bool old_isnull;
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bool new_isnull;
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bool need_change = false;
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bool need_free = false;
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bool need_delold = false;
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bool has_nulls = false;
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Size maxDataLen;
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char toast_action[MaxHeapAttributeNumber];
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char toast_nulls[MaxHeapAttributeNumber];
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Datum toast_values[MaxHeapAttributeNumber];
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int32 toast_sizes[MaxHeapAttributeNumber];
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bool toast_free[MaxHeapAttributeNumber];
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bool toast_delold[MaxHeapAttributeNumber];
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/* ----------
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* Get the tuple descriptor, the number of and attribute
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* descriptors and the location of the tuple values.
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* ----------
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*/
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tupleDesc = rel->rd_att;
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numAttrs = tupleDesc->natts;
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att = tupleDesc->attrs;
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/* ----------
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* Then collect information about the values given
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* ----------
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*/
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memset(toast_action, ' ', numAttrs * sizeof(char));
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memset(toast_nulls, ' ', numAttrs * sizeof(char));
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memset(toast_free, 0, numAttrs * sizeof(bool));
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memset(toast_delold, 0, numAttrs * sizeof(bool));
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for (i = 0; i < numAttrs; i++)
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{
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varattrib *old_value;
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varattrib *new_value;
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if (oldtup != NULL)
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{
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/* ----------
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* For UPDATE get the old and new values of this attribute
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* ----------
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*/
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old_value = (varattrib *)DatumGetPointer(
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heap_getattr(oldtup, i + 1, tupleDesc, &old_isnull));
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toast_values[i] =
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heap_getattr(newtup, i + 1, tupleDesc, &new_isnull);
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new_value = (varattrib *)DatumGetPointer(toast_values[i]);
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/* ----------
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* If the old value is an external stored one, check if it
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* has changed so we have to delete it later.
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* ----------
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*/
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if (!old_isnull && att[i]->attlen == -1 &&
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VARATT_IS_EXTERNAL(old_value))
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{
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if (new_isnull || !VARATT_IS_EXTERNAL(new_value) ||
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old_value->va_content.va_external.va_rowid !=
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new_value->va_content.va_external.va_rowid ||
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old_value->va_content.va_external.va_attno !=
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new_value->va_content.va_external.va_attno)
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{
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/* ----------
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* The old external store value isn't needed any
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* more after the update
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* ----------
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*/
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toast_delold[i] = true;
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need_delold = true;
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}
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else
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{
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/* ----------
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* This attribute isn't changed by this update
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* so we reuse the original reference to the old
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* value in the new tuple.
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* ----------
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*/
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toast_action[i] = 'p';
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toast_sizes[i] = VARATT_SIZE(toast_values[i]);
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continue;
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}
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}
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}
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else
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{
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/* ----------
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* For INSERT simply get the new value
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* ----------
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*/
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toast_values[i] =
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heap_getattr(newtup, i + 1, tupleDesc, &new_isnull);
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}
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/* ----------
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* Handle NULL attributes
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* ----------
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*/
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if (new_isnull)
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{
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toast_action[i] = 'p';
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toast_nulls[i] = 'n';
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has_nulls = true;
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continue;
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}
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/* ----------
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* Now look at varsize attributes
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* ----------
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*/
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if (att[i]->attlen == -1)
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{
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/* ----------
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* If the table's attribute says PLAIN always, force it so.
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* ----------
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*/
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if (att[i]->attstorage == 'p')
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toast_action[i] = 'p';
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/* ----------
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* We took care of UPDATE above, so any TOASTed value we find
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* still in the tuple must be someone else's we cannot reuse.
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* Expand it to plain (and, probably, toast it again below).
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* ----------
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*/
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if (VARATT_IS_EXTENDED(DatumGetPointer(toast_values[i])))
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{
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toast_values[i] = PointerGetDatum(heap_tuple_untoast_attr(
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(varattrib *)DatumGetPointer(toast_values[i])));
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toast_free[i] = true;
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need_change = true;
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need_free = true;
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}
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/* ----------
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* Remember the size of this attribute
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* ----------
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*/
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toast_sizes[i] = VARATT_SIZE(DatumGetPointer(toast_values[i]));
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}
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else
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{
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/* ----------
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* Not a variable size attribute, plain storage always
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* ----------
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*/
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toast_action[i] = 'p';
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toast_sizes[i] = att[i]->attlen;
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}
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}
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/* ----------
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* Compress and/or save external until data fits
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*
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* 1: Inline compress attributes with attstorage 'x'
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* 2: Store attributes with attstorage 'x' or 'e' external
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* 3: Inline compress attributes with attstorage 'm'
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* 4: Store attributes with attstorage 'm' external
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* ----------
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*/
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maxDataLen = offsetof(HeapTupleHeaderData, t_bits);
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if (has_nulls)
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maxDataLen += BITMAPLEN(numAttrs);
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maxDataLen = (MaxTupleSize / 4) - MAXALIGN(maxDataLen);
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/* ----------
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* Look for attributes with attstorage 'x' to compress
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* ----------
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*/
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while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) >
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maxDataLen)
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{
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int biggest_attno = -1;
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int32 biggest_size = MAXALIGN(sizeof(varattrib));
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Datum old_value;
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/* ----------
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* Search for the biggest yet uncompressed internal attribute
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* ----------
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*/
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for (i = 0; i < numAttrs; i++)
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{
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if (toast_action[i] == 'p')
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continue;
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if (VARATT_IS_EXTENDED(toast_values[i]))
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continue;
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if (att[i]->attstorage != 'x')
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continue;
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if (toast_sizes[i] > biggest_size)
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{
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biggest_attno = i;
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biggest_size = toast_sizes[i];
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}
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}
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if (biggest_attno < 0)
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break;
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/* ----------
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* Compress it inline
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* ----------
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*/
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i = biggest_attno;
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old_value = toast_values[i];
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toast_values[i] = toast_compress_datum(toast_values[i]);
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if (toast_free[i])
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pfree(DatumGetPointer(old_value));
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toast_free[i] = true;
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toast_sizes[i] = VARATT_SIZE(toast_values[i]);
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need_change = true;
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need_free = true;
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}
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/* ----------
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* Second we look for attributes of attstorage 'x' or 'e' that
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* are still inline.
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* ----------
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*/
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while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) >
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maxDataLen && rel->rd_rel->reltoastrelid != InvalidOid)
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{
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int biggest_attno = -1;
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int32 biggest_size = MAXALIGN(sizeof(varattrib));
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Datum old_value;
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/* ----------
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* Search for the biggest yet inlined attribute with
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* attstorage = 'x' or 'e'
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* ----------
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*/
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for (i = 0; i < numAttrs; i++)
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{
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if (toast_action[i] == 'p')
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continue;
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if (VARATT_IS_EXTERNAL(toast_values[i]))
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continue;
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if (att[i]->attstorage != 'x' && att[i]->attstorage != 'e')
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continue;
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if (toast_sizes[i] > biggest_size)
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{
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biggest_attno = i;
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biggest_size = toast_sizes[i];
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}
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}
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if (biggest_attno < 0)
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break;
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/* ----------
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* Store this external
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* ----------
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*/
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i = biggest_attno;
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old_value = toast_values[i];
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toast_action[i] = 'p';
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toast_values[i] = toast_save_datum(rel,
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newtup->t_data->t_oid,
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i + 1,
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toast_values[i]);
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if (toast_free[i])
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pfree(DatumGetPointer(old_value));
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toast_free[i] = true;
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toast_sizes[i] = VARATT_SIZE(toast_values[i]);
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need_change = true;
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need_free = true;
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}
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|
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/* ----------
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* Round 3 - this time we take attributes with storage
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* 'm' into compression
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* ----------
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*/
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while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) >
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maxDataLen)
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{
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int biggest_attno = -1;
|
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int32 biggest_size = MAXALIGN(sizeof(varattrib));
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Datum old_value;
|
|
|
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/* ----------
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|
* Search for the biggest yet uncompressed internal attribute
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* ----------
|
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*/
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for (i = 0; i < numAttrs; i++)
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{
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if (toast_action[i] == 'p')
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continue;
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if (VARATT_IS_EXTENDED(toast_values[i]))
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continue;
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if (att[i]->attstorage != 'm')
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continue;
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if (toast_sizes[i] > biggest_size)
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{
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biggest_attno = i;
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biggest_size = toast_sizes[i];
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}
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}
|
|
|
|
if (biggest_attno < 0)
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break;
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|
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/* ----------
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* Compress it inline
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* ----------
|
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*/
|
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i = biggest_attno;
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old_value = toast_values[i];
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toast_values[i] = toast_compress_datum(toast_values[i]);
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|
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if (toast_free[i])
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pfree(DatumGetPointer(old_value));
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|
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toast_free[i] = true;
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toast_sizes[i] = VARATT_SIZE(toast_values[i]);
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|
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need_change = true;
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need_free = true;
|
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}
|
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|
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/* ----------
|
|
* Finally we store attributes of type 'm' external
|
|
* ----------
|
|
*/
|
|
while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) >
|
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maxDataLen && rel->rd_rel->reltoastrelid != InvalidOid)
|
|
{
|
|
int biggest_attno = -1;
|
|
int32 biggest_size = MAXALIGN(sizeof(varattrib));
|
|
Datum old_value;
|
|
|
|
/* ----------
|
|
* Search for the biggest yet inlined attribute with
|
|
* attstorage = 'x' or 'e'
|
|
* ----------
|
|
*/
|
|
for (i = 0; i < numAttrs; i++)
|
|
{
|
|
if (toast_action[i] == 'p')
|
|
continue;
|
|
if (VARATT_IS_EXTERNAL(toast_values[i]))
|
|
continue;
|
|
if (att[i]->attstorage != 'm')
|
|
continue;
|
|
if (toast_sizes[i] > biggest_size)
|
|
{
|
|
biggest_attno = i;
|
|
biggest_size = toast_sizes[i];
|
|
}
|
|
}
|
|
|
|
if (biggest_attno < 0)
|
|
break;
|
|
|
|
/* ----------
|
|
* Store this external
|
|
* ----------
|
|
*/
|
|
i = biggest_attno;
|
|
old_value = toast_values[i];
|
|
toast_action[i] = 'p';
|
|
toast_values[i] = toast_save_datum(rel,
|
|
newtup->t_data->t_oid,
|
|
i + 1,
|
|
toast_values[i]);
|
|
if (toast_free[i])
|
|
pfree(DatumGetPointer(old_value));
|
|
|
|
toast_free[i] = true;
|
|
toast_sizes[i] = VARATT_SIZE(toast_values[i]);
|
|
|
|
need_change = true;
|
|
need_free = true;
|
|
}
|
|
|
|
/* ----------
|
|
* In the case we toasted any values, we need to build
|
|
* a new heap tuple with the changed values.
|
|
* ----------
|
|
*/
|
|
if (need_change)
|
|
{
|
|
char *new_data;
|
|
int32 new_len;
|
|
MemoryContext oldcxt;
|
|
HeapTupleHeader olddata;
|
|
|
|
/* ----------
|
|
* Calculate the new size of the tuple
|
|
* ----------
|
|
*/
|
|
new_len = offsetof(HeapTupleHeaderData, t_bits);
|
|
if (has_nulls)
|
|
new_len += BITMAPLEN(numAttrs);
|
|
new_len = MAXALIGN(new_len);
|
|
new_len += ComputeDataSize(tupleDesc, toast_values, toast_nulls);
|
|
|
|
/* ----------
|
|
* Remember the old memory location of the tuple (for below),
|
|
* switch to the memory context of the HeapTuple structure
|
|
* and allocate the new tuple.
|
|
* ----------
|
|
*/
|
|
olddata = newtup->t_data;
|
|
oldcxt = MemoryContextSwitchTo(newtup->t_datamcxt);
|
|
new_data = palloc(new_len);
|
|
|
|
/* ----------
|
|
* Put the tuple header and the changed values into place
|
|
* ----------
|
|
*/
|
|
memcpy(new_data, newtup->t_data, newtup->t_data->t_hoff);
|
|
newtup->t_data = (HeapTupleHeader)new_data;
|
|
newtup->t_len = new_len;
|
|
|
|
DataFill((char *)(MAXALIGN((long)new_data +
|
|
offsetof(HeapTupleHeaderData, t_bits) +
|
|
((has_nulls) ? BITMAPLEN(numAttrs) : 0))),
|
|
tupleDesc,
|
|
toast_values,
|
|
toast_nulls,
|
|
&(newtup->t_data->t_infomask),
|
|
has_nulls ? newtup->t_data->t_bits : NULL);
|
|
|
|
/* ----------
|
|
* In the case we modified a previously modified tuple again,
|
|
* free the memory from the previous run
|
|
* ----------
|
|
*/
|
|
if ((char *)olddata != ((char *)newtup + HEAPTUPLESIZE))
|
|
pfree(olddata);
|
|
|
|
/* ----------
|
|
* Switch back to the old memory context
|
|
* ----------
|
|
*/
|
|
MemoryContextSwitchTo(oldcxt);
|
|
}
|
|
|
|
/* ----------
|
|
* Free allocated temp values
|
|
* ----------
|
|
*/
|
|
if (need_free)
|
|
for (i = 0; i < numAttrs; i++)
|
|
if (toast_free[i])
|
|
pfree(DatumGetPointer(toast_values[i]));
|
|
|
|
/* ----------
|
|
* Delete external values from the old tuple
|
|
* ----------
|
|
*/
|
|
if (need_delold)
|
|
for (i = 0; i < numAttrs; i++)
|
|
if (toast_delold[i])
|
|
toast_delete_datum(rel,
|
|
heap_getattr(oldtup, i + 1, tupleDesc, &old_isnull));
|
|
|
|
return;
|
|
}
|
|
|
|
|
|
/* ----------
|
|
* toast_compress_datum -
|
|
*
|
|
* Create a compressed version of a datum
|
|
* ----------
|
|
*/
|
|
static Datum
|
|
toast_compress_datum(Datum value)
|
|
{
|
|
varattrib *tmp;
|
|
|
|
tmp = (varattrib *)palloc(sizeof(PGLZ_Header) + VARATT_SIZE(value));
|
|
pglz_compress(VARATT_DATA(value), VARATT_SIZE(value) - VARHDRSZ,
|
|
(PGLZ_Header *)tmp,
|
|
PGLZ_strategy_default);
|
|
VARATT_SIZEP(tmp) |= VARATT_FLAG_COMPRESSED;
|
|
|
|
return PointerGetDatum(tmp);
|
|
}
|
|
|
|
|
|
/* ----------
|
|
* toast_save_datum -
|
|
*
|
|
* Save one single datum into the secondary relation and return
|
|
* a varattrib reference for it.
|
|
* ----------
|
|
*/
|
|
static Datum
|
|
toast_save_datum(Relation rel, Oid mainoid, int16 attno, Datum value)
|
|
{
|
|
Relation toastrel;
|
|
Relation toastidx;
|
|
HeapTuple toasttup;
|
|
InsertIndexResult idxres;
|
|
TupleDesc toasttupDesc;
|
|
Datum t_values[3];
|
|
char t_nulls[4];
|
|
varattrib *result;
|
|
char chunk_data[MaxTupleSize];
|
|
int32 chunk_size;
|
|
int32 chunk_seq = 0;
|
|
char *data_p;
|
|
int32 data_todo;
|
|
|
|
/* ----------
|
|
* Create the varattrib reference
|
|
* ----------
|
|
*/
|
|
result = (varattrib *)palloc(sizeof(varattrib));
|
|
|
|
result->va_header = sizeof(varattrib) | VARATT_FLAG_EXTERNAL;
|
|
if (VARATT_IS_COMPRESSED(value))
|
|
{
|
|
result->va_header |= VARATT_FLAG_COMPRESSED;
|
|
result->va_content.va_external.va_rawsize =
|
|
((varattrib *)value)->va_content.va_compressed.va_rawsize;
|
|
}
|
|
else
|
|
result->va_content.va_external.va_rawsize = VARATT_SIZE(value);
|
|
|
|
result->va_content.va_external.va_extsize =
|
|
VARATT_SIZE(value) - VARHDRSZ;
|
|
result->va_content.va_external.va_valueid = newoid();
|
|
result->va_content.va_external.va_toastrelid =
|
|
rel->rd_rel->reltoastrelid;
|
|
result->va_content.va_external.va_toastidxid =
|
|
rel->rd_rel->reltoastidxid;
|
|
result->va_content.va_external.va_rowid = mainoid;
|
|
result->va_content.va_external.va_attno = attno;
|
|
|
|
/* ----------
|
|
* Initialize constant parts of the tuple data
|
|
* ----------
|
|
*/
|
|
t_values[0] = ObjectIdGetDatum(result->va_content.va_external.va_valueid);
|
|
t_values[2] = PointerGetDatum(chunk_data);
|
|
t_nulls[0] = ' ';
|
|
t_nulls[1] = ' ';
|
|
t_nulls[2] = ' ';
|
|
t_nulls[3] = '\0';
|
|
|
|
/* ----------
|
|
* Get the data to process
|
|
* ----------
|
|
*/
|
|
data_p = VARATT_DATA(value);
|
|
data_todo = VARATT_SIZE(value) - VARHDRSZ;
|
|
|
|
/* ----------
|
|
* Open the toast relation
|
|
* ----------
|
|
*/
|
|
toastrel = heap_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
|
|
if (toastrel == NULL)
|
|
elog(ERROR, "Failed to open secondary relation of %s",
|
|
nameout(&(rel->rd_rel->relname)));
|
|
toasttupDesc = toastrel->rd_att;
|
|
toastidx = index_open(rel->rd_rel->reltoastidxid);
|
|
if (toastidx == NULL)
|
|
elog(ERROR, "Failed to open index for secondary relation of %s",
|
|
nameout(&(rel->rd_rel->relname)));
|
|
|
|
/* ----------
|
|
* Split up the item into chunks
|
|
* ----------
|
|
*/
|
|
while (data_todo > 0)
|
|
{
|
|
/* ----------
|
|
* Calculate the size of this chunk
|
|
* ----------
|
|
*/
|
|
chunk_size = (TOAST_MAX_CHUNK_SIZE < data_todo) ?
|
|
TOAST_MAX_CHUNK_SIZE : data_todo;
|
|
|
|
/* ----------
|
|
* Build a tuple
|
|
* ----------
|
|
*/
|
|
t_values[1] = (Datum)(chunk_seq++);
|
|
VARATT_SIZEP(chunk_data) = chunk_size + VARHDRSZ;
|
|
memcpy(VARATT_DATA(chunk_data), data_p, chunk_size);
|
|
toasttup = heap_formtuple(toasttupDesc, t_values, t_nulls);
|
|
if (!HeapTupleIsValid(toasttup))
|
|
elog(ERROR, "Failed to build TOAST tuple");
|
|
|
|
/* ----------
|
|
* Store it and create the index entry
|
|
* ----------
|
|
*/
|
|
heap_insert(toastrel, toasttup);
|
|
idxres = index_insert(toastidx, t_values, t_nulls,
|
|
&(toasttup->t_self),
|
|
toastrel);
|
|
if (idxres == NULL)
|
|
elog(ERROR, "Failed to insert index entry for TOAST tuple");
|
|
|
|
/* ----------
|
|
* Free memory
|
|
* ----------
|
|
*/
|
|
heap_freetuple(toasttup);
|
|
pfree(idxres);
|
|
|
|
/* ----------
|
|
* Move on to next chunk
|
|
* ----------
|
|
*/
|
|
data_todo -= chunk_size;
|
|
data_p += chunk_size;
|
|
}
|
|
|
|
/* ----------
|
|
* Done - close toast relation and return the reference
|
|
* ----------
|
|
*/
|
|
index_close(toastidx);
|
|
heap_close(toastrel, RowExclusiveLock);
|
|
|
|
return PointerGetDatum(result);
|
|
}
|
|
|
|
|
|
/* ----------
|
|
* toast_delete_datum -
|
|
*
|
|
* Delete a single external stored value.
|
|
* ----------
|
|
*/
|
|
static void
|
|
toast_delete_datum(Relation rel, Datum value)
|
|
{
|
|
register varattrib *attr = (varattrib *)value;
|
|
Relation toastrel;
|
|
Relation toastidx;
|
|
ScanKeyData toastkey;
|
|
IndexScanDesc toastscan;
|
|
HeapTupleData toasttup;
|
|
RetrieveIndexResult indexRes;
|
|
Buffer buffer;
|
|
|
|
if (!VARATT_IS_EXTERNAL(attr))
|
|
return;
|
|
|
|
/* ----------
|
|
* Open the toast relation and it's index
|
|
* ----------
|
|
*/
|
|
toastrel = heap_open(attr->va_content.va_external.va_toastrelid,
|
|
RowExclusiveLock);
|
|
if (toastrel == NULL)
|
|
elog(ERROR, "Failed to open secondary relation at TOAST fetch");
|
|
toastidx = index_open(attr->va_content.va_external.va_toastidxid);
|
|
if (toastidx == NULL)
|
|
elog(ERROR, "Failed to open index of secondary relation at TOAST fetch");
|
|
|
|
/* ----------
|
|
* Setup a scan key to fetch from the index by va_valueid
|
|
* ----------
|
|
*/
|
|
ScanKeyEntryInitialize(&toastkey,
|
|
(bits16) 0,
|
|
(AttrNumber) 1,
|
|
(RegProcedure) F_OIDEQ,
|
|
ObjectIdGetDatum(attr->va_content.va_external.va_valueid));
|
|
|
|
/* ----------
|
|
* Read the chunks by index
|
|
* ----------
|
|
*/
|
|
toastscan = index_beginscan(toastidx, false, 1, &toastkey);
|
|
while ((indexRes = index_getnext(toastscan, ForwardScanDirection)) != NULL)
|
|
{
|
|
toasttup.t_self = indexRes->heap_iptr;
|
|
heap_fetch(toastrel, SnapshotAny, &toasttup, &buffer);
|
|
pfree(indexRes);
|
|
|
|
if (!toasttup.t_data)
|
|
continue;
|
|
|
|
/* ----------
|
|
* Have a chunk, delete it
|
|
* ----------
|
|
*/
|
|
heap_delete(toastrel, &toasttup.t_self, NULL);
|
|
|
|
ReleaseBuffer(buffer);
|
|
}
|
|
|
|
/* ----------
|
|
* End scan and close relations
|
|
* ----------
|
|
*/
|
|
index_endscan(toastscan);
|
|
index_close(toastidx);
|
|
heap_close(toastrel, RowExclusiveLock);
|
|
|
|
return;
|
|
}
|
|
|
|
|
|
/* ----------
|
|
* toast_fetch_datum -
|
|
*
|
|
* Reconstruct an in memory varattrib from the chunks saved
|
|
* in the toast relation
|
|
* ----------
|
|
*/
|
|
static varattrib *
|
|
toast_fetch_datum(varattrib *attr)
|
|
{
|
|
Relation toastrel;
|
|
Relation toastidx;
|
|
ScanKeyData toastkey;
|
|
IndexScanDesc toastscan;
|
|
HeapTupleData toasttup;
|
|
HeapTuple ttup;
|
|
TupleDesc toasttupDesc;
|
|
RetrieveIndexResult indexRes;
|
|
Buffer buffer;
|
|
|
|
varattrib *result;
|
|
int32 ressize;
|
|
int32 residx;
|
|
int numchunks;
|
|
Datum chunk;
|
|
bool isnull;
|
|
|
|
char *chunks_found;
|
|
char *chunks_expected;
|
|
|
|
ressize = attr->va_content.va_external.va_extsize;
|
|
numchunks = (ressize / TOAST_MAX_CHUNK_SIZE) + 1;
|
|
|
|
chunks_found = palloc(numchunks);
|
|
chunks_expected = palloc(numchunks);
|
|
memset(chunks_found, 0, numchunks);
|
|
memset(chunks_expected, 1, numchunks);
|
|
|
|
result = (varattrib *)palloc(ressize + VARHDRSZ);
|
|
VARATT_SIZEP(result) = ressize + VARHDRSZ;
|
|
if (VARATT_IS_COMPRESSED(attr))
|
|
VARATT_SIZEP(result) |= VARATT_FLAG_COMPRESSED;
|
|
|
|
/* ----------
|
|
* Open the toast relation and it's index
|
|
* ----------
|
|
*/
|
|
toastrel = heap_open(attr->va_content.va_external.va_toastrelid,
|
|
AccessShareLock);
|
|
if (toastrel == NULL)
|
|
elog(ERROR, "Failed to open secondary relation at TOAST fetch");
|
|
toasttupDesc = toastrel->rd_att;
|
|
toastidx = index_open(attr->va_content.va_external.va_toastidxid);
|
|
if (toastidx == NULL)
|
|
elog(ERROR, "Failed to open index of secondary relation at TOAST fetch");
|
|
|
|
/* ----------
|
|
* Setup a scan key to fetch from the index by va_valueid
|
|
* ----------
|
|
*/
|
|
ScanKeyEntryInitialize(&toastkey,
|
|
(bits16) 0,
|
|
(AttrNumber) 1,
|
|
(RegProcedure) F_OIDEQ,
|
|
ObjectIdGetDatum(attr->va_content.va_external.va_valueid));
|
|
|
|
/* ----------
|
|
* Read the chunks by index
|
|
* ----------
|
|
*/
|
|
toastscan = index_beginscan(toastidx, false, 1, &toastkey);
|
|
while ((indexRes = index_getnext(toastscan, ForwardScanDirection)) != NULL)
|
|
{
|
|
toasttup.t_self = indexRes->heap_iptr;
|
|
heap_fetch(toastrel, SnapshotAny, &toasttup, &buffer);
|
|
pfree(indexRes);
|
|
|
|
if (toasttup.t_data == NULL)
|
|
continue;
|
|
ttup = &toasttup;
|
|
|
|
/* ----------
|
|
* Have a chunk, extract the sequence number and the data
|
|
* ----------
|
|
*/
|
|
residx = (int32)heap_getattr(ttup, 2, toasttupDesc, &isnull);
|
|
chunk = heap_getattr(ttup, 3, toasttupDesc, &isnull);
|
|
|
|
/* ----------
|
|
* Some checks on the data we've found
|
|
* ----------
|
|
*/
|
|
if (residx * TOAST_MAX_CHUNK_SIZE + VARATT_SIZE(chunk) - VARHDRSZ
|
|
> ressize)
|
|
elog(ERROR, "chunk data exceeds original data size for "
|
|
"toast value %d",
|
|
attr->va_content.va_external.va_valueid);
|
|
if (chunks_found[residx]++ > 0)
|
|
elog(ERROR, "chunk %d for toast value %d appears multiple times",
|
|
residx,
|
|
attr->va_content.va_external.va_valueid);
|
|
|
|
/* ----------
|
|
* Copy the data into our result
|
|
* ----------
|
|
*/
|
|
memcpy(((char *)VARATT_DATA(result)) + residx * TOAST_MAX_CHUNK_SIZE,
|
|
VARATT_DATA(chunk),
|
|
VARATT_SIZE(chunk) - VARHDRSZ);
|
|
|
|
ReleaseBuffer(buffer);
|
|
}
|
|
|
|
/* ----------
|
|
* Final checks that we successfully fetched the datum
|
|
* ----------
|
|
*/
|
|
if (memcmp(chunks_found, chunks_expected, numchunks) != 0)
|
|
elog(ERROR, "not all toast chunks found for value %d",
|
|
attr->va_content.va_external.va_valueid);
|
|
pfree(chunks_expected);
|
|
pfree(chunks_found);
|
|
|
|
/* ----------
|
|
* End scan and close relations
|
|
* ----------
|
|
*/
|
|
index_endscan(toastscan);
|
|
index_close(toastidx);
|
|
heap_close(toastrel, AccessShareLock);
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
#endif /* TUPLE_TOASTER_ACTIVE */
|