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Diffstat (limited to 'src/backend/access/common/detoast.c')
| -rw-r--r-- | src/backend/access/common/detoast.c | 869 |
1 files changed, 869 insertions, 0 deletions
diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c new file mode 100644 index 00000000000..c8b49d6a124 --- /dev/null +++ b/src/backend/access/common/detoast.c @@ -0,0 +1,869 @@ +/*------------------------------------------------------------------------- + * + * detoast.c + * Retrieve compressed or external variable size attributes. + * + * Copyright (c) 2000-2019, PostgreSQL Global Development Group + * + * IDENTIFICATION + * src/backend/access/common/detoast.c + * + *------------------------------------------------------------------------- + */ + +#include "postgres.h" + +#include "access/detoast.h" +#include "access/genam.h" +#include "access/heaptoast.h" +#include "access/table.h" +#include "access/toast_internals.h" +#include "common/pg_lzcompress.h" +#include "utils/expandeddatum.h" +#include "utils/fmgroids.h" +#include "utils/rel.h" + +static struct varlena *toast_fetch_datum(struct varlena *attr); +static struct varlena *toast_fetch_datum_slice(struct varlena *attr, + int32 sliceoffset, int32 length); +static struct varlena *toast_decompress_datum(struct varlena *attr); +static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength); + +/* ---------- + * heap_tuple_fetch_attr - + * + * Public entry point to get back a toasted value from + * external source (possibly still in compressed format). + * + * This will return a datum that contains all the data internally, ie, not + * relying on external storage or memory, but it can still be compressed or + * have a short header. Note some callers assume that if the input is an + * EXTERNAL datum, the result will be a pfree'able chunk. + * ---------- + */ +struct varlena * +heap_tuple_fetch_attr(struct varlena *attr) +{ + struct varlena *result; + + if (VARATT_IS_EXTERNAL_ONDISK(attr)) + { + /* + * This is an external stored plain value + */ + result = toast_fetch_datum(attr); + } + else if (VARATT_IS_EXTERNAL_INDIRECT(attr)) + { + /* + * This is an indirect pointer --- dereference it + */ + struct varatt_indirect redirect; + + VARATT_EXTERNAL_GET_POINTER(redirect, attr); + attr = (struct varlena *) redirect.pointer; + + /* nested indirect Datums aren't allowed */ + Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr)); + + /* recurse if value is still external in some other way */ + if (VARATT_IS_EXTERNAL(attr)) + return heap_tuple_fetch_attr(attr); + + /* + * Copy into the caller's memory context, in case caller tries to + * pfree the result. + */ + result = (struct varlena *) palloc(VARSIZE_ANY(attr)); + memcpy(result, attr, VARSIZE_ANY(attr)); + } + else if (VARATT_IS_EXTERNAL_EXPANDED(attr)) + { + /* + * This is an expanded-object pointer --- get flat format + */ + ExpandedObjectHeader *eoh; + Size resultsize; + + eoh = DatumGetEOHP(PointerGetDatum(attr)); + resultsize = EOH_get_flat_size(eoh); + result = (struct varlena *) palloc(resultsize); + EOH_flatten_into(eoh, (void *) result, resultsize); + } + 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. The result is always non-extended varlena form. + * + * Note some callers assume that if the input is an EXTERNAL or COMPRESSED + * datum, the result will be a pfree'able chunk. + * ---------- + */ +struct varlena * +heap_tuple_untoast_attr(struct varlena *attr) +{ + if (VARATT_IS_EXTERNAL_ONDISK(attr)) + { + /* + * This is an externally stored datum --- fetch it back from there + */ + attr = toast_fetch_datum(attr); + /* If it's compressed, decompress it */ + if (VARATT_IS_COMPRESSED(attr)) + { + struct varlena *tmp = attr; + + attr = toast_decompress_datum(tmp); + pfree(tmp); + } + } + else if (VARATT_IS_EXTERNAL_INDIRECT(attr)) + { + /* + * This is an indirect pointer --- dereference it + */ + struct varatt_indirect redirect; + + VARATT_EXTERNAL_GET_POINTER(redirect, attr); + attr = (struct varlena *) redirect.pointer; + + /* nested indirect Datums aren't allowed */ + Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr)); + + /* recurse in case value is still extended in some other way */ + attr = heap_tuple_untoast_attr(attr); + + /* if it isn't, we'd better copy it */ + if (attr == (struct varlena *) redirect.pointer) + { + struct varlena *result; + + result = (struct varlena *) palloc(VARSIZE_ANY(attr)); + memcpy(result, attr, VARSIZE_ANY(attr)); + attr = result; + } + } + else if (VARATT_IS_EXTERNAL_EXPANDED(attr)) + { + /* + * This is an expanded-object pointer --- get flat format + */ + attr = heap_tuple_fetch_attr(attr); + /* flatteners are not allowed to produce compressed/short output */ + Assert(!VARATT_IS_EXTENDED(attr)); + } + else if (VARATT_IS_COMPRESSED(attr)) + { + /* + * This is a compressed value inside of the main tuple + */ + attr = toast_decompress_datum(attr); + } + else if (VARATT_IS_SHORT(attr)) + { + /* + * This is a short-header varlena --- convert to 4-byte header format + */ + Size data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT; + Size new_size = data_size + VARHDRSZ; + struct varlena *new_attr; + + new_attr = (struct varlena *) palloc(new_size); + SET_VARSIZE(new_attr, new_size); + memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size); + attr = new_attr; + } + + return attr; +} + + +/* ---------- + * heap_tuple_untoast_attr_slice - + * + * Public entry point to get back part of a toasted value + * from compression or external storage. + * ---------- + */ +struct varlena * +heap_tuple_untoast_attr_slice(struct varlena *attr, + int32 sliceoffset, int32 slicelength) +{ + struct varlena *preslice; + struct varlena *result; + char *attrdata; + int32 attrsize; + + if (VARATT_IS_EXTERNAL_ONDISK(attr)) + { + struct varatt_external toast_pointer; + + VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + + /* fast path for non-compressed external datums */ + if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer)) + return toast_fetch_datum_slice(attr, sliceoffset, slicelength); + + /* fetch it back (compressed marker will get set automatically) */ + preslice = toast_fetch_datum(attr); + } + else if (VARATT_IS_EXTERNAL_INDIRECT(attr)) + { + struct varatt_indirect redirect; + + VARATT_EXTERNAL_GET_POINTER(redirect, attr); + + /* nested indirect Datums aren't allowed */ + Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer)); + + return heap_tuple_untoast_attr_slice(redirect.pointer, + sliceoffset, slicelength); + } + else if (VARATT_IS_EXTERNAL_EXPANDED(attr)) + { + /* pass it off to heap_tuple_fetch_attr to flatten */ + preslice = heap_tuple_fetch_attr(attr); + } + else + preslice = attr; + + Assert(!VARATT_IS_EXTERNAL(preslice)); + + if (VARATT_IS_COMPRESSED(preslice)) + { + struct varlena *tmp = preslice; + + /* Decompress enough to encompass the slice and the offset */ + if (slicelength > 0 && sliceoffset >= 0) + preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset); + else + preslice = toast_decompress_datum(tmp); + + if (tmp != attr) + pfree(tmp); + } + + if (VARATT_IS_SHORT(preslice)) + { + attrdata = VARDATA_SHORT(preslice); + attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT; + } + else + { + attrdata = VARDATA(preslice); + attrsize = VARSIZE(preslice) - VARHDRSZ; + } + + /* slicing of datum for compressed cases and plain value */ + + if (sliceoffset >= attrsize) + { + sliceoffset = 0; + slicelength = 0; + } + + if (((sliceoffset + slicelength) > attrsize) || slicelength < 0) + slicelength = attrsize - sliceoffset; + + result = (struct varlena *) palloc(slicelength + VARHDRSZ); + SET_VARSIZE(result, slicelength + VARHDRSZ); + + memcpy(VARDATA(result), attrdata + sliceoffset, slicelength); + + if (preslice != attr) + pfree(preslice); + + return result; +} + +/* ---------- + * toast_fetch_datum - + * + * Reconstruct an in memory Datum from the chunks saved + * in the toast relation + * ---------- + */ +static struct varlena * +toast_fetch_datum(struct varlena *attr) +{ + Relation toastrel; + Relation *toastidxs; + ScanKeyData toastkey; + SysScanDesc toastscan; + HeapTuple ttup; + TupleDesc toasttupDesc; + struct varlena *result; + struct varatt_external toast_pointer; + int32 ressize; + int32 residx, + nextidx; + int32 numchunks; + Pointer chunk; + bool isnull; + char *chunkdata; + int32 chunksize; + int num_indexes; + int validIndex; + SnapshotData SnapshotToast; + + if (!VARATT_IS_EXTERNAL_ONDISK(attr)) + elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums"); + + /* Must copy to access aligned fields */ + VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + + ressize = toast_pointer.va_extsize; + numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1; + + result = (struct varlena *) palloc(ressize + VARHDRSZ); + + if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer)) + SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ); + else + SET_VARSIZE(result, ressize + VARHDRSZ); + + /* + * Open the toast relation and its indexes + */ + toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock); + toasttupDesc = toastrel->rd_att; + + /* Look for the valid index of the toast relation */ + validIndex = toast_open_indexes(toastrel, + AccessShareLock, + &toastidxs, + &num_indexes); + + /* + * Setup a scan key to fetch from the index by va_valueid + */ + ScanKeyInit(&toastkey, + (AttrNumber) 1, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(toast_pointer.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; + + init_toast_snapshot(&SnapshotToast); + toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex], + &SnapshotToast, 1, &toastkey); + while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL) + { + /* + * Have a chunk, extract the sequence number and the data + */ + residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull)); + Assert(!isnull); + chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull)); + Assert(!isnull); + if (!VARATT_IS_EXTENDED(chunk)) + { + chunksize = VARSIZE(chunk) - VARHDRSZ; + chunkdata = VARDATA(chunk); + } + else if (VARATT_IS_SHORT(chunk)) + { + /* could happen due to heap_form_tuple doing its thing */ + chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT; + chunkdata = VARDATA_SHORT(chunk); + } + else + { + /* should never happen */ + elog(ERROR, "found toasted toast chunk for toast value %u in %s", + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)); + chunksize = 0; /* keep compiler quiet */ + chunkdata = NULL; + } + + /* + * Some checks on the data we've found + */ + if (residx != nextidx) + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s", + residx, nextidx, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)))); + if (residx < numchunks - 1) + { + if (chunksize != TOAST_MAX_CHUNK_SIZE) + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s", + chunksize, (int) TOAST_MAX_CHUNK_SIZE, + residx, numchunks, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)))); + } + else if (residx == numchunks - 1) + { + if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize) + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s", + chunksize, + (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE), + residx, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)))); + } + else + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s", + residx, + 0, numchunks - 1, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)))); + + /* + * Copy the data into proper place in our result + */ + memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE, + chunkdata, + chunksize); + + nextidx++; + } + + /* + * Final checks that we successfully fetched the datum + */ + if (nextidx != numchunks) + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("missing chunk number %d for toast value %u in %s", + nextidx, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)))); + + /* + * End scan and close relations + */ + systable_endscan_ordered(toastscan); + toast_close_indexes(toastidxs, num_indexes, AccessShareLock); + table_close(toastrel, AccessShareLock); + + return result; +} + +/* ---------- + * toast_fetch_datum_slice - + * + * Reconstruct a segment of a Datum from the chunks saved + * in the toast relation + * + * Note that this function only supports non-compressed external datums. + * ---------- + */ +static struct varlena * +toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length) +{ + Relation toastrel; + Relation *toastidxs; + ScanKeyData toastkey[3]; + int nscankeys; + SysScanDesc toastscan; + HeapTuple ttup; + TupleDesc toasttupDesc; + struct varlena *result; + struct varatt_external toast_pointer; + int32 attrsize; + int32 residx; + int32 nextidx; + int numchunks; + int startchunk; + int endchunk; + int32 startoffset; + int32 endoffset; + int totalchunks; + Pointer chunk; + bool isnull; + char *chunkdata; + int32 chunksize; + int32 chcpystrt; + int32 chcpyend; + int num_indexes; + int validIndex; + SnapshotData SnapshotToast; + + if (!VARATT_IS_EXTERNAL_ONDISK(attr)) + elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums"); + + /* Must copy to access aligned fields */ + VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + + /* + * It's nonsense to fetch slices of a compressed datum -- this isn't lo_* + * we can't return a compressed datum which is meaningful to toast later + */ + Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer)); + + attrsize = toast_pointer.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 = (struct varlena *) palloc(length + VARHDRSZ); + + SET_VARSIZE(result, length + VARHDRSZ); + + 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 its indexes + */ + toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock); + toasttupDesc = toastrel->rd_att; + + /* Look for the valid index of toast relation */ + validIndex = toast_open_indexes(toastrel, + AccessShareLock, + &toastidxs, + &num_indexes); + + /* + * Setup a scan key to fetch from the index. This is either two keys or + * three depending on the number of chunks. + */ + ScanKeyInit(&toastkey[0], + (AttrNumber) 1, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(toast_pointer.va_valueid)); + + /* + * Use equality condition for one chunk, a range condition otherwise: + */ + if (numchunks == 1) + { + ScanKeyInit(&toastkey[1], + (AttrNumber) 2, + BTEqualStrategyNumber, F_INT4EQ, + Int32GetDatum(startchunk)); + nscankeys = 2; + } + else + { + ScanKeyInit(&toastkey[1], + (AttrNumber) 2, + BTGreaterEqualStrategyNumber, F_INT4GE, + Int32GetDatum(startchunk)); + ScanKeyInit(&toastkey[2], + (AttrNumber) 2, + BTLessEqualStrategyNumber, F_INT4LE, + Int32GetDatum(endchunk)); + nscankeys = 3; + } + + /* + * Read the chunks by index + * + * The index is on (valueid, chunkidx) so they will come in order + */ + init_toast_snapshot(&SnapshotToast); + nextidx = startchunk; + toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex], + &SnapshotToast, nscankeys, toastkey); + while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL) + { + /* + * Have a chunk, extract the sequence number and the data + */ + residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull)); + Assert(!isnull); + chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull)); + Assert(!isnull); + if (!VARATT_IS_EXTENDED(chunk)) + { + chunksize = VARSIZE(chunk) - VARHDRSZ; + chunkdata = VARDATA(chunk); + } + else if (VARATT_IS_SHORT(chunk)) + { + /* could happen due to heap_form_tuple doing its thing */ + chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT; + chunkdata = VARDATA_SHORT(chunk); + } + else + { + /* should never happen */ + elog(ERROR, "found toasted toast chunk for toast value %u in %s", + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)); + chunksize = 0; /* keep compiler quiet */ + chunkdata = NULL; + } + + /* + * 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 in %s", + residx, nextidx, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)); + if (residx < totalchunks - 1) + { + if (chunksize != TOAST_MAX_CHUNK_SIZE) + elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice", + chunksize, (int) TOAST_MAX_CHUNK_SIZE, + residx, totalchunks, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)); + } + else if (residx == totalchunks - 1) + { + if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize) + elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice", + chunksize, + (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE), + residx, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)); + } + else + elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s", + residx, + 0, totalchunks - 1, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)); + + /* + * 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(VARDATA(result) + + (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt, + chunkdata + 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 in %s", + nextidx, + toast_pointer.va_valueid, + RelationGetRelationName(toastrel)); + + /* + * End scan and close relations + */ + systable_endscan_ordered(toastscan); + toast_close_indexes(toastidxs, num_indexes, AccessShareLock); + table_close(toastrel, AccessShareLock); + + return result; +} + +/* ---------- + * toast_decompress_datum - + * + * Decompress a compressed version of a varlena datum + */ +static struct varlena * +toast_decompress_datum(struct varlena *attr) +{ + struct varlena *result; + + Assert(VARATT_IS_COMPRESSED(attr)); + + result = (struct varlena *) + palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ); + SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ); + + if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr), + VARSIZE(attr) - TOAST_COMPRESS_HDRSZ, + VARDATA(result), + TOAST_COMPRESS_RAWSIZE(attr), true) < 0) + elog(ERROR, "compressed data is corrupted"); + + return result; +} + + +/* ---------- + * toast_decompress_datum_slice - + * + * Decompress the front of a compressed version of a varlena datum. + * offset handling happens in heap_tuple_untoast_attr_slice. + * Here we just decompress a slice from the front. + */ +static struct varlena * +toast_decompress_datum_slice(struct varlena *attr, int32 slicelength) +{ + struct varlena *result; + int32 rawsize; + + Assert(VARATT_IS_COMPRESSED(attr)); + + result = (struct varlena *) palloc(slicelength + VARHDRSZ); + + rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr), + VARSIZE(attr) - TOAST_COMPRESS_HDRSZ, + VARDATA(result), + slicelength, false); + if (rawsize < 0) + elog(ERROR, "compressed data is corrupted"); + + SET_VARSIZE(result, rawsize + VARHDRSZ); + return result; +} + +/* ---------- + * toast_raw_datum_size - + * + * Return the raw (detoasted) size of a varlena datum + * (including the VARHDRSZ header) + * ---------- + */ +Size +toast_raw_datum_size(Datum value) +{ + struct varlena *attr = (struct varlena *) DatumGetPointer(value); + Size result; + + if (VARATT_IS_EXTERNAL_ONDISK(attr)) + { + /* va_rawsize is the size of the original datum -- including header */ + struct varatt_external toast_pointer; + + VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + result = toast_pointer.va_rawsize; + } + else if (VARATT_IS_EXTERNAL_INDIRECT(attr)) + { + struct varatt_indirect toast_pointer; + + VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + + /* nested indirect Datums aren't allowed */ + Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer)); + + return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer)); + } + else if (VARATT_IS_EXTERNAL_EXPANDED(attr)) + { + result = EOH_get_flat_size(DatumGetEOHP(value)); + } + else if (VARATT_IS_COMPRESSED(attr)) + { + /* here, va_rawsize is just the payload size */ + result = VARRAWSIZE_4B_C(attr) + VARHDRSZ; + } + else if (VARATT_IS_SHORT(attr)) + { + /* + * we have to normalize the header length to VARHDRSZ or else the + * callers of this function will be confused. + */ + result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ; + } + else + { + /* plain untoasted datum */ + result = VARSIZE(attr); + } + return result; +} + +/* ---------- + * toast_datum_size + * + * Return the physical storage size (possibly compressed) of a varlena datum + * ---------- + */ +Size +toast_datum_size(Datum value) +{ + struct varlena *attr = (struct varlena *) DatumGetPointer(value); + Size result; + + if (VARATT_IS_EXTERNAL_ONDISK(attr)) + { + /* + * Attribute is stored externally - return the extsize whether + * compressed or not. We do not count the size of the toast pointer + * ... should we? + */ + struct varatt_external toast_pointer; + + VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + result = toast_pointer.va_extsize; + } + else if (VARATT_IS_EXTERNAL_INDIRECT(attr)) + { + struct varatt_indirect toast_pointer; + + VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + + /* nested indirect Datums aren't allowed */ + Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr)); + + return toast_datum_size(PointerGetDatum(toast_pointer.pointer)); + } + else if (VARATT_IS_EXTERNAL_EXPANDED(attr)) + { + result = EOH_get_flat_size(DatumGetEOHP(value)); + } + else if (VARATT_IS_SHORT(attr)) + { + result = VARSIZE_SHORT(attr); + } + else + { + /* + * Attribute is stored inline either compressed or not, just calculate + * the size of the datum in either case. + */ + result = VARSIZE(attr); + } + return result; +} |