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Diffstat (limited to 'src/backend/access/heap/tuptoaster.c')
| -rw-r--r-- | src/backend/access/heap/tuptoaster.c | 1307 |
1 files changed, 0 insertions, 1307 deletions
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c deleted file mode 100644 index 3c66aed1db1..00000000000 --- a/src/backend/access/heap/tuptoaster.c +++ /dev/null @@ -1,1307 +0,0 @@ -/*------------------------------------------------------------------------- - * - * tuptoaster.c - * Support routines for external and compressed storage of - * variable size attributes. - * - * Copyright (c) 2000-2002, PostgreSQL Global Development Group - * - * - * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.32 2002/05/27 19:53:33 tgl Exp $ - * - * - * INTERFACE ROUTINES - * heap_tuple_toast_attrs - - * Try to make a given tuple fit into one page by compressing - * or moving off attributes - * - * heap_tuple_untoast_attr - - * Fetch back a given value from the "secondary" relation - * - *------------------------------------------------------------------------- - */ - -#include "postgres.h" - -#include <unistd.h> -#include <fcntl.h> - -#include "access/heapam.h" -#include "access/genam.h" -#include "access/tuptoaster.h" -#include "catalog/catalog.h" -#include "utils/rel.h" -#include "utils/builtins.h" -#include "utils/fmgroids.h" -#include "utils/pg_lzcompress.h" - - -#undef TOAST_DEBUG - -static void toast_delete(Relation rel, HeapTuple oldtup); -static void toast_delete_datum(Relation rel, Datum value); -static void toast_insert_or_update(Relation rel, HeapTuple newtup, - HeapTuple oldtup); -static Datum toast_save_datum(Relation rel, Datum value); -static varattrib *toast_fetch_datum(varattrib *attr); -static varattrib *toast_fetch_datum_slice(varattrib *attr, - int32 sliceoffset, int32 length); - - -/* ---------- - * heap_tuple_toast_attrs - - * - * This is the central public entry point for toasting from heapam. - * - * Calls the appropriate event specific action. - * ---------- - */ -void -heap_tuple_toast_attrs(Relation rel, HeapTuple newtup, HeapTuple oldtup) -{ - if (newtup == NULL) - toast_delete(rel, oldtup); - else - toast_insert_or_update(rel, newtup, oldtup); -} - - -/* ---------- - * heap_tuple_fetch_attr - - * - * Public entry point to get back a toasted value - * external storage (possibly still in compressed format). - * ---------- - */ -varattrib * -heap_tuple_fetch_attr(varattrib *attr) -{ - varattrib *result; - - if (VARATT_IS_EXTERNAL(attr)) - { - /* - * This is an external stored plain value - */ - result = toast_fetch_datum(attr); - } - else - { - /* - * This is a plain value inside of the main tuple - why am I - * called? - */ - result = attr; - } - - return result; -} - - -/* ---------- - * heap_tuple_untoast_attr - - * - * Public entry point to get back a toasted value from compression - * or external storage. - * ---------- - */ -varattrib * -heap_tuple_untoast_attr(varattrib *attr) -{ - varattrib *result; - - if (VARATT_IS_EXTERNAL(attr)) - { - if (VARATT_IS_COMPRESSED(attr)) - { - /* ---------- - * This is an external stored compressed value - * Fetch it from the toast heap and decompress. - * ---------- - */ - varattrib *tmp; - - tmp = toast_fetch_datum(attr); - result = (varattrib *) palloc(attr->va_content.va_external.va_rawsize - + VARHDRSZ); - VARATT_SIZEP(result) = attr->va_content.va_external.va_rawsize - + VARHDRSZ; - pglz_decompress((PGLZ_Header *) tmp, VARATT_DATA(result)); - - pfree(tmp); - } - else - { - /* - * This is an external stored plain value - */ - result = toast_fetch_datum(attr); - } - } - else if (VARATT_IS_COMPRESSED(attr)) - { - /* - * This is a compressed value inside of the main tuple - */ - result = (varattrib *) palloc(attr->va_content.va_compressed.va_rawsize - + VARHDRSZ); - VARATT_SIZEP(result) = attr->va_content.va_compressed.va_rawsize - + VARHDRSZ; - pglz_decompress((PGLZ_Header *) attr, VARATT_DATA(result)); - } - else - - /* - * This is a plain value inside of the main tuple - why am I - * called? - */ - return attr; - - return result; -} - - -/* ---------- - * heap_tuple_untoast_attr_slice - - * - * Public entry point to get back part of a toasted value - * from compression or external storage. - * ---------- - */ -varattrib * -heap_tuple_untoast_attr_slice(varattrib *attr, int32 sliceoffset, int32 slicelength) -{ - varattrib *preslice; - varattrib *result; - int32 attrsize; - - if (VARATT_IS_COMPRESSED(attr)) - { - varattrib *tmp; - - if (VARATT_IS_EXTERNAL(attr)) - { - tmp = toast_fetch_datum(attr); - } - else - { - tmp = attr; /* compressed in main tuple */ - } - - preslice = (varattrib *) palloc(attr->va_content.va_external.va_rawsize - + VARHDRSZ); - VARATT_SIZEP(preslice) = attr->va_content.va_external.va_rawsize + VARHDRSZ; - pglz_decompress((PGLZ_Header *) tmp, VARATT_DATA(preslice)); - - if (tmp != attr) - pfree(tmp); - } - else - { - /* Plain value */ - if (VARATT_IS_EXTERNAL(attr)) - { - /* fast path */ - return (toast_fetch_datum_slice(attr, sliceoffset, slicelength)); - } - else - { - preslice = attr; - } - } - - /* slicing of datum for compressed cases and plain value */ - - attrsize = VARSIZE(preslice) - VARHDRSZ; - if (sliceoffset >= attrsize) - { - sliceoffset = 0; - slicelength = 0; - } - - if (((sliceoffset + slicelength) > attrsize) || slicelength < 0) - { - slicelength = attrsize - sliceoffset; - } - - result = (varattrib *) palloc(slicelength + VARHDRSZ); - VARATT_SIZEP(result) = slicelength + VARHDRSZ; - - memcpy(VARDATA(result), VARDATA(preslice) + sliceoffset, slicelength); - - if (preslice != attr) pfree(preslice); - - return result; -} - - -/* ---------- - * toast_raw_datum_size - - * - * Return the raw (detoasted) size of a varlena datum - * ---------- - */ -Size -toast_raw_datum_size(Datum value) -{ - varattrib *attr = (varattrib *) DatumGetPointer(value); - Size result; - - if (VARATT_IS_COMPRESSED(attr)) - { - /* - * va_rawsize shows the original data size, whether the datum is - * external or not. - */ - result = attr->va_content.va_compressed.va_rawsize + VARHDRSZ; - } - else if (VARATT_IS_EXTERNAL(attr)) - { - /* - * an uncompressed external attribute has rawsize including the - * header (not too consistent!) - */ - result = attr->va_content.va_external.va_rawsize; - } - else - { - /* plain untoasted datum */ - result = VARSIZE(attr); - } - return result; -} - - -/* ---------- - * toast_delete - - * - * Cascaded delete toast-entries on DELETE - * ---------- - */ -static void -toast_delete(Relation rel, HeapTuple oldtup) -{ - TupleDesc tupleDesc; - Form_pg_attribute *att; - int numAttrs; - int i; - Datum value; - bool isnull; - - /* - * Get the tuple descriptor, the number of and attribute descriptors. - */ - tupleDesc = rel->rd_att; - numAttrs = tupleDesc->natts; - att = tupleDesc->attrs; - - /* - * Check for external stored attributes and delete them from the - * secondary relation. - */ - for (i = 0; i < numAttrs; i++) - { - if (att[i]->attlen == -1) - { - value = heap_getattr(oldtup, i + 1, tupleDesc, &isnull); - if (!isnull && VARATT_IS_EXTERNAL(value)) - toast_delete_datum(rel, value); - } - } -} - - -/* ---------- - * toast_insert_or_update - - * - * Delete no-longer-used toast-entries and create new ones to - * make the new tuple fit on INSERT or UPDATE - * ---------- - */ -static void -toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup) -{ - TupleDesc tupleDesc; - Form_pg_attribute *att; - int numAttrs; - int i; - bool old_isnull; - bool new_isnull; - - bool need_change = false; - bool need_free = false; - bool need_delold = false; - bool has_nulls = false; - - Size maxDataLen; - - char toast_action[MaxHeapAttributeNumber]; - char toast_nulls[MaxHeapAttributeNumber]; - Datum toast_values[MaxHeapAttributeNumber]; - int32 toast_sizes[MaxHeapAttributeNumber]; - bool toast_free[MaxHeapAttributeNumber]; - bool toast_delold[MaxHeapAttributeNumber]; - - /* - * Get the tuple descriptor, the number of and attribute descriptors - * and the location of the tuple values. - */ - tupleDesc = rel->rd_att; - numAttrs = tupleDesc->natts; - att = tupleDesc->attrs; - - /* ---------- - * Then collect information about the values given - * - * NOTE: toast_action[i] can have these values: - * ' ' default handling - * 'p' already processed --- don't touch it - * 'x' incompressible, but OK to move off - * ---------- - */ - memset(toast_action, ' ', numAttrs * sizeof(char)); - memset(toast_nulls, ' ', numAttrs * sizeof(char)); - memset(toast_free, 0, numAttrs * sizeof(bool)); - memset(toast_delold, 0, numAttrs * sizeof(bool)); - for (i = 0; i < numAttrs; i++) - { - varattrib *old_value; - varattrib *new_value; - - if (oldtup != NULL) - { - /* - * For UPDATE get the old and new values of this attribute - */ - old_value = (varattrib *) DatumGetPointer( - heap_getattr(oldtup, i + 1, tupleDesc, &old_isnull)); - toast_values[i] = - heap_getattr(newtup, i + 1, tupleDesc, &new_isnull); - new_value = (varattrib *) DatumGetPointer(toast_values[i]); - - /* - * If the old value is an external stored one, check if it has - * changed so we have to delete it later. - */ - if (!old_isnull && att[i]->attlen == -1 && - VARATT_IS_EXTERNAL(old_value)) - { - if (new_isnull || !VARATT_IS_EXTERNAL(new_value) || - old_value->va_content.va_external.va_valueid != - new_value->va_content.va_external.va_valueid || - old_value->va_content.va_external.va_toastrelid != - new_value->va_content.va_external.va_toastrelid) - { - /* - * The old external store value isn't needed any more - * after the update - */ - toast_delold[i] = true; - need_delold = true; - } - else - { - /* - * This attribute isn't changed by this update so we - * reuse the original reference to the old value in - * the new tuple. - */ - toast_action[i] = 'p'; - toast_sizes[i] = VARATT_SIZE(toast_values[i]); - continue; - } - } - } - else - { - /* - * For INSERT simply get the new value - */ - toast_values[i] = - heap_getattr(newtup, i + 1, tupleDesc, &new_isnull); - } - - /* - * Handle NULL attributes - */ - if (new_isnull) - { - toast_action[i] = 'p'; - toast_nulls[i] = 'n'; - has_nulls = true; - continue; - } - - /* - * Now look at varsize attributes - */ - if (att[i]->attlen == -1) - { - /* - * If the table's attribute says PLAIN always, force it so. - */ - if (att[i]->attstorage == 'p') - toast_action[i] = 'p'; - - /* - * We took care of UPDATE above, so any external value we find - * still in the tuple must be someone else's we cannot reuse. - * Expand it to plain (and, probably, toast it again below). - */ - if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i]))) - { - toast_values[i] = PointerGetDatum(heap_tuple_untoast_attr( - (varattrib *) DatumGetPointer(toast_values[i]))); - toast_free[i] = true; - need_change = true; - need_free = true; - } - - /* - * Remember the size of this attribute - */ - toast_sizes[i] = VARATT_SIZE(DatumGetPointer(toast_values[i])); - } - else - { - /* - * Not a variable size attribute, plain storage always - */ - toast_action[i] = 'p'; - toast_sizes[i] = att[i]->attlen; - } - } - - /* ---------- - * Compress and/or save external until data fits into target length - * - * 1: Inline compress attributes with attstorage 'x' - * 2: Store attributes with attstorage 'x' or 'e' external - * 3: Inline compress attributes with attstorage 'm' - * 4: Store attributes with attstorage 'm' external - * ---------- - */ - maxDataLen = offsetof(HeapTupleHeaderData, t_bits); - if (has_nulls) - maxDataLen += BITMAPLEN(numAttrs); - maxDataLen = TOAST_TUPLE_TARGET - MAXALIGN(maxDataLen); - - /* - * Look for attributes with attstorage 'x' to compress - */ - while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) > - maxDataLen) - { - int biggest_attno = -1; - int32 biggest_size = MAXALIGN(sizeof(varattrib)); - Datum old_value; - Datum new_value; - - /* - * Search for the biggest yet uncompressed internal attribute - */ - for (i = 0; i < numAttrs; i++) - { - if (toast_action[i] != ' ') - continue; - if (VARATT_IS_EXTENDED(toast_values[i])) - continue; - if (att[i]->attstorage != 'x') - continue; - if (toast_sizes[i] > biggest_size) - { - biggest_attno = i; - biggest_size = toast_sizes[i]; - } - } - - if (biggest_attno < 0) - break; - - /* - * Attempt to compress it inline - */ - i = biggest_attno; - old_value = toast_values[i]; - new_value = toast_compress_datum(old_value); - - if (DatumGetPointer(new_value) != NULL) - { - /* successful compression */ - if (toast_free[i]) - pfree(DatumGetPointer(old_value)); - toast_values[i] = new_value; - toast_free[i] = true; - toast_sizes[i] = VARATT_SIZE(toast_values[i]); - need_change = true; - need_free = true; - } - else - { - /* - * incompressible data, ignore on subsequent compression - * passes - */ - toast_action[i] = 'x'; - } - } - - /* - * Second we look for attributes of attstorage 'x' or 'e' that are - * still inline. - */ - while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) > - 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 equals '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 != 'x' && att[i]->attstorage != 'e') - 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, 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; - } - - /* - * Round 3 - this time we take attributes with storage 'm' into - * compression - */ - while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) > - maxDataLen) - { - int biggest_attno = -1; - int32 biggest_size = MAXALIGN(sizeof(varattrib)); - Datum old_value; - Datum new_value; - - /* - * Search for the biggest yet uncompressed internal attribute - */ - for (i = 0; i < numAttrs; i++) - { - if (toast_action[i] != ' ') - continue; - if (VARATT_IS_EXTENDED(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; - - /* - * Attempt to compress it inline - */ - i = biggest_attno; - old_value = toast_values[i]; - new_value = toast_compress_datum(old_value); - - if (DatumGetPointer(new_value) != NULL) - { - /* successful compression */ - if (toast_free[i]) - pfree(DatumGetPointer(old_value)); - toast_values[i] = new_value; - toast_free[i] = true; - toast_sizes[i] = VARATT_SIZE(toast_values[i]); - need_change = true; - need_free = true; - } - else - { - /* - * incompressible data, ignore on subsequent compression - * passes - */ - toast_action[i] = 'x'; - } - } - - /* - * Finally we store attributes of type 'm' external - */ - while (MAXALIGN(ComputeDataSize(tupleDesc, toast_values, toast_nulls)) > - 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 = 'm' - *-------- - */ - 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, 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) - { - HeapTupleHeader olddata = newtup->t_data; - char *new_data; - int32 new_len; - - /* - * Calculate the new size of the tuple. Header size should not - * change, but data size might. - */ - new_len = offsetof(HeapTupleHeaderData, t_bits); - if (has_nulls) - new_len += BITMAPLEN(numAttrs); - new_len = MAXALIGN(new_len); - Assert(new_len == olddata->t_hoff); - new_len += ComputeDataSize(tupleDesc, toast_values, toast_nulls); - - /* - * Allocate new tuple in same context as old one. - */ - new_data = (char *) MemoryContextAlloc(newtup->t_datamcxt, new_len); - newtup->t_data = (HeapTupleHeader) new_data; - newtup->t_len = new_len; - - /* - * Put the tuple header and the changed values into place - */ - memcpy(new_data, olddata, olddata->t_hoff); - - DataFill((char *) new_data + olddata->t_hoff, - 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); - } - - /* - * 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)); -} - - -/* ---------- - * toast_compress_datum - - * - * Create a compressed version of a varlena datum - * - * If we fail (ie, compressed result is actually bigger than original) - * then return NULL. We must not use compressed data if it'd expand - * the tuple! - * ---------- - */ -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); - if (VARATT_SIZE(tmp) < VARATT_SIZE(value)) - { - /* successful compression */ - VARATT_SIZEP(tmp) |= VARATT_FLAG_COMPRESSED; - return PointerGetDatum(tmp); - } - else - { - /* incompressible data */ - pfree(tmp); - return PointerGetDatum(NULL); - } -} - - -/* ---------- - * 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, Datum value) -{ - Relation toastrel; - Relation toastidx; - HeapTuple toasttup; - InsertIndexResult idxres; - TupleDesc toasttupDesc; - Datum t_values[3]; - char t_nulls[3]; - varattrib *result; - struct - { - struct varlena hdr; - char data[TOAST_MAX_CHUNK_SIZE]; - } chunk_data; - 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; - - /* - * 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] = ' '; - - /* - * 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); - toasttupDesc = toastrel->rd_att; - toastidx = index_open(toastrel->rd_rel->reltoastidxid); - - /* - * Split up the item into chunks - */ - while (data_todo > 0) - { - /* - * Calculate the size of this chunk - */ - chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo); - - /* - * Build a tuple and store it - */ - t_values[1] = Int32GetDatum(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"); - - simple_heap_insert(toastrel, toasttup); - - /* - * Create the index entry. We cheat a little here by not using - * FormIndexDatum: this relies on the knowledge that the index - * columns are the same as the initial columns of the table. - * - * Note also that there had better not be any user-created index on - * the TOAST table, since we don't bother to update anything else. - */ - idxres = index_insert(toastidx, t_values, t_nulls, - &(toasttup->t_self), - toastrel, toastidx->rd_uniqueindex); - if (idxres == NULL) - elog(ERROR, "Failed to insert index entry for TOAST tuple"); - - /* - * Free memory - */ - pfree(idxres); - heap_freetuple(toasttup); - - /* - * 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) -{ - varattrib *attr = (varattrib *) DatumGetPointer(value); - Relation toastrel; - Relation toastidx; - ScanKeyData toastkey; - IndexScanDesc toastscan; - HeapTuple toasttup; - - 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); - toastidx = index_open(toastrel->rd_rel->reltoastidxid); - - /* - * Setup a scan key to fetch from the index by va_valueid (we don't - * particularly care whether we see them in sequence or not) - */ - ScanKeyEntryInitialize(&toastkey, - (bits16) 0, - (AttrNumber) 1, - (RegProcedure) F_OIDEQ, - ObjectIdGetDatum(attr->va_content.va_external.va_valueid)); - - /* - * Find the chunks by index - */ - toastscan = index_beginscan(toastrel, toastidx, SnapshotToast, - 1, &toastkey); - while ((toasttup = index_getnext(toastscan, ForwardScanDirection)) != NULL) - { - /* - * Have a chunk, delete it - */ - simple_heap_delete(toastrel, &toasttup->t_self); - } - - /* - * End scan and close relations - */ - index_endscan(toastscan); - index_close(toastidx); - heap_close(toastrel, RowExclusiveLock); -} - - -/* ---------- - * 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; - HeapTuple ttup; - TupleDesc toasttupDesc; - varattrib *result; - int32 ressize; - int32 residx, - nextidx; - int32 numchunks; - Pointer chunk; - bool isnull; - int32 chunksize; - - ressize = attr->va_content.va_external.va_extsize; - numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1; - - 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 its index - */ - toastrel = heap_open(attr->va_content.va_external.va_toastrelid, - AccessShareLock); - toasttupDesc = toastrel->rd_att; - toastidx = index_open(toastrel->rd_rel->reltoastidxid); - - /* - * 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 - * - * Note that because the index is actually on (valueid, chunkidx) - * we will see the chunks in chunkidx order, even though we didn't - * explicitly ask for it. - */ - nextidx = 0; - - toastscan = index_beginscan(toastrel, toastidx, SnapshotToast, - 1, &toastkey); - while ((ttup = index_getnext(toastscan, ForwardScanDirection)) != NULL) - { - /* - * Have a chunk, extract the sequence number and the data - */ - residx = DatumGetInt32(heap_getattr(ttup, 2, toasttupDesc, &isnull)); - Assert(!isnull); - chunk = DatumGetPointer(heap_getattr(ttup, 3, toasttupDesc, &isnull)); - Assert(!isnull); - chunksize = VARATT_SIZE(chunk) - VARHDRSZ; - - /* - * Some checks on the data we've found - */ - if (residx != nextidx) - elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u", - residx, nextidx, - attr->va_content.va_external.va_valueid); - if (residx < numchunks - 1) - { - if (chunksize != TOAST_MAX_CHUNK_SIZE) - elog(ERROR, "unexpected chunk size %d in chunk %d for toast value %u", - chunksize, residx, - attr->va_content.va_external.va_valueid); - } - else if (residx < numchunks) - { - if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize) - elog(ERROR, "unexpected chunk size %d in chunk %d for toast value %u", - chunksize, residx, - attr->va_content.va_external.va_valueid); - } - else - elog(ERROR, "unexpected chunk number %d for toast value %u", - residx, - attr->va_content.va_external.va_valueid); - - /* - * Copy the data into proper place in our result - */ - memcpy(((char *) VARATT_DATA(result)) + residx * TOAST_MAX_CHUNK_SIZE, - VARATT_DATA(chunk), - chunksize); - - nextidx++; - } - - /* - * Final checks that we successfully fetched the datum - */ - if (nextidx != numchunks) - elog(ERROR, "missing chunk number %d for toast value %u", - nextidx, - attr->va_content.va_external.va_valueid); - - /* - * End scan and close relations - */ - index_endscan(toastscan); - index_close(toastidx); - heap_close(toastrel, AccessShareLock); - - return result; -} - -/* ---------- - * toast_fetch_datum_slice - - * - * Reconstruct a segment of a varattrib from the chunks saved - * in the toast relation - * ---------- - */ -static varattrib * -toast_fetch_datum_slice(varattrib *attr, int32 sliceoffset, int32 length) -{ - Relation toastrel; - Relation toastidx; - ScanKeyData toastkey[3]; - int nscankeys; - IndexScanDesc toastscan; - HeapTuple ttup; - TupleDesc toasttupDesc; - varattrib *result; - int32 attrsize; - int32 residx; - int32 nextidx; - int numchunks; - int startchunk; - int endchunk; - int32 startoffset; - int32 endoffset; - int totalchunks; - Pointer chunk; - bool isnull; - int32 chunksize; - int32 chcpystrt; - int32 chcpyend; - - attrsize = attr->va_content.va_external.va_extsize; - totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1; - - if (sliceoffset >= attrsize) - { - sliceoffset = 0; - length = 0; - } - - if (((sliceoffset + length) > attrsize) || length < 0) - { - length = attrsize - sliceoffset; - } - - result = (varattrib *) palloc(length + VARHDRSZ); - VARATT_SIZEP(result) = length + VARHDRSZ; - - if (VARATT_IS_COMPRESSED(attr)) - VARATT_SIZEP(result) |= VARATT_FLAG_COMPRESSED; - - if (length == 0) return (result); /* Can save a lot of work at this point! */ - - startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE; - endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE; - numchunks = (endchunk - startchunk ) + 1; - - startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE; - endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE; - - /* - * Open the toast relation and it's index - */ - toastrel = heap_open(attr->va_content.va_external.va_toastrelid, - AccessShareLock); - toasttupDesc = toastrel->rd_att; - toastidx = index_open(toastrel->rd_rel->reltoastidxid); - - /* - * Setup a scan key to fetch from the index. This is either two keys - * or three depending on the number of chunks. - */ - ScanKeyEntryInitialize(&toastkey[0], - (bits16) 0, - (AttrNumber) 1, - (RegProcedure) F_OIDEQ, - ObjectIdGetDatum(attr->va_content.va_external.va_valueid)); - /* - * Now dependent on number of chunks: - */ - - if (numchunks == 1) - { - ScanKeyEntryInitialize(&toastkey[1], - (bits16) 0, - (AttrNumber) 2, - (RegProcedure) F_INT4EQ, - Int32GetDatum(startchunk)); - nscankeys = 2; - } - else - { - ScanKeyEntryInitialize(&toastkey[1], - (bits16) 0, - (AttrNumber) 2, - (RegProcedure) F_INT4GE, - Int32GetDatum(startchunk)); - ScanKeyEntryInitialize(&toastkey[2], - (bits16) 0, - (AttrNumber) 2, - (RegProcedure) F_INT4LE, - Int32GetDatum(endchunk)); - nscankeys = 3; - } - - /* - * Read the chunks by index - * - * The index is on (valueid, chunkidx) so they will come in order - */ - nextidx = startchunk; - toastscan = index_beginscan(toastrel, toastidx, SnapshotToast, - nscankeys, toastkey); - while ((ttup = index_getnext(toastscan, ForwardScanDirection)) != NULL) - { - /* - * Have a chunk, extract the sequence number and the data - */ - residx = DatumGetInt32(heap_getattr(ttup, 2, toasttupDesc, &isnull)); - Assert(!isnull); - chunk = DatumGetPointer(heap_getattr(ttup, 3, toasttupDesc, &isnull)); - Assert(!isnull); - chunksize = VARATT_SIZE(chunk) - VARHDRSZ; - - /* - * Some checks on the data we've found - */ - if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk)) - elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u", - residx, nextidx, - attr->va_content.va_external.va_valueid); - if (residx < totalchunks - 1) - { - if (chunksize != TOAST_MAX_CHUNK_SIZE) - elog(ERROR, "unexpected chunk size %d in chunk %d for toast value %u", - chunksize, residx, - attr->va_content.va_external.va_valueid); - } - else - { - if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize) - elog(ERROR, "unexpected chunk size %d in chunk %d for toast value %u", - chunksize, residx, - attr->va_content.va_external.va_valueid); - } - - /* - * Copy the data into proper place in our result - */ - chcpystrt = 0; - chcpyend = chunksize - 1; - if (residx == startchunk) chcpystrt = startoffset; - if (residx == endchunk) chcpyend = endoffset; - - memcpy(((char *) VARATT_DATA(result)) + - (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) +chcpystrt, - VARATT_DATA(chunk) + chcpystrt, - (chcpyend - chcpystrt) + 1); - - nextidx++; - } - - /* - * Final checks that we successfully fetched the datum - */ - if ( nextidx != (endchunk + 1)) - elog(ERROR, "missing chunk number %d for toast value %u", - nextidx, - attr->va_content.va_external.va_valueid); - - /* - * End scan and close relations - */ - index_endscan(toastscan); - index_close(toastidx); - heap_close(toastrel, AccessShareLock); - - return result; -} |